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Security consulting giant Kroll disclosed today that a SIM-swapping attack against one of its employees led to the theft of user information for multiple cryptocurrency platforms that are relying on Kroll services in their ongoing bankruptcy proceedings. And there are indications that fraudsters may already be exploiting the stolen data in phishing attacks.
Cryptocurrency lender BlockFi and the now-collapsed crypto trading platform FTX each disclosed data breaches this week thanks to a recent SIM-swapping attack targeting an employee of Kroll — the company handling both firms’ bankruptcy restructuring.
In a statement released today, New York City-based Kroll said it was informed that on Aug. 19, 2023, someone targeted a T-Mobile phone number belonging to a Kroll employee “in a highly sophisticated ‘SIM swapping’ attack.”
“Specifically, T-Mobile, without any authority from or contact with Kroll or its employees, transferred that employee’s phone number to the threat actor’s phone at their request,” the statement continues. “As a result, it appears the threat actor gained access to certain files containing personal information of bankruptcy claimants in the matters of BlockFi, FTX and Genesis.”
T-Mobile has not yet responded to requests for comment.
Countless websites and online services use SMS text messages for both password resets and multi-factor authentication. This means that stealing someone’s phone number often can let cybercriminals hijack the target’s entire digital life in short order — including access to any financial, email and social media accounts tied to that phone number.
SIM-swapping groups will often call employees on their mobile devices, pretend to be someone from the company’s IT department, and then try to get the employee to visit a phishing website that mimics the company’s login page.
Multiple SIM-swapping gangs have had great success using this method to target T-Mobile employees for the purposes of reselling a cybercrime service that can be hired to divert any T-Mobile user’s text messages and phone calls to another device.
In February 2023, KrebsOnSecurity chronicled SIM-swapping attacks claimed by these groups against T-Mobile employees in more than 100 separate incidents in the second half of 2022. The average cost to SIM swap any T-Mobile phone number was approximately $1,500.
The unfortunate result of the SIM-swap against the Kroll employee is that people who had financial ties to BlockFi, FTX, or Genesis now face increased risk of becoming targets of SIM-swapping and phishing attacks themselves.
And there is some indication this is already happening. Multiple readers who said they got breach notices from Kroll today also shared phishing emails they received this morning that spoofed FTX and claimed, “You have been identified as an eligible client to begin withdrawing digital assets from your FTX account.”
A phishing message targeting FTX users that went out en masse today.
A major portion of Kroll’s business comes from helping organizations manage cyber risk. Kroll is often called in to investigate data breaches, and it also sells identity protection services to companies that recently experienced a breach and are grasping at ways to demonstrate that they doing something to protect their customers from further harm.
Kroll did not respond to questions. But it’s a good bet that BlockFi, FTX and Genesis customers will soon enjoy yet another offering of free credit monitoring as a result of the T-Mobile SIM swap.
Kroll’s website says it employs “elite cyber risk leaders uniquely positioned to deliver end-to-end cyber security services worldwide.” Apparently, these elite cyber risk leaders did not consider the increased attack surface presented by their employees using T-Mobile for wireless service.
The SIM-swapping attack against Kroll is a timely reminder that you should do whatever you can to minimize your reliance on mobile phone companies for your security. For example, many online services require you to provide a phone number upon registering an account, but that number can often be removed from your profile afterwards.
Why do I suggest this? Many online services allow users to reset their passwords just by clicking a link sent via SMS, and this unfortunately widespread practice has turned mobile phone numbers into de facto identity documents. Which means losing control over your phone number thanks to an unauthorized SIM swap or mobile number port-out, divorce, job termination or financial crisis can be devastating.
If you haven’t done so lately, take a moment to inventory your most important online accounts, and see how many of them can still have their password reset by receiving an SMS at the phone number on file. This may require stepping through the website’s account recovery or lost password flow.
If the account that stores your mobile phone number does not allow you to delete your number, check to see whether there is an option to disallow SMS or phone calls for authentication and account recovery. If more secure options are available, such as a security key or a one-time code from a mobile authentication app, please take advantage of those instead. The website 2fa.directory is a good starting point for this analysis.
Now, you might think that the mobile providers would share some culpability when a customer suffers a financial loss because a mobile store employee got tricked into transferring that customer’s phone number to criminals. But earlier this year, a California judge dismissed a lawsuit against AT&T that stemmed from a 2017 SIM-swapping attack which netted the thieves more than $24 million in cryptocurrency.
A new breach involving data from nine million AT&T customers is a fresh reminder that your mobile provider likely collects and shares a great deal of information about where you go and what you do with your mobile device — unless and until you affirmatively opt out of this data collection. Here’s a primer on why you might want to do that, and how.
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Telecommunications giant AT&T disclosed this month that a breach at a marketing vendor exposed certain account information for nine million customers. AT&T said the data exposed did not include sensitive information, such as credit card or Social Security numbers, or account passwords, but was limited to “Customer Proprietary Network Information” (CPNI), such as the number of lines on an account.
Certain questions may be coming to mind right now, like “What the heck is CPNI?” And, ‘If it’s so ‘customer proprietary,’ why is AT&T sharing it with marketers?” Also maybe, “What can I do about it?” Read on for answers to all three questions.
AT&T’s disclosure said the information exposed included customer first name, wireless account number, wireless phone number and email address. In addition, a small percentage of customer records also exposed the rate plan name, past due amounts, monthly payment amounts and minutes used.
CPNI refers to customer-specific “metadata” about the account and account usage, and may include:
-Called phone numbers
-Time of calls
-Length of calls
-Cost and billing of calls
-Service features
-Premium services, such as directory call assistance
According to a succinct CPNI explainer at TechTarget, CPNI is private and protected information that cannot be used for advertising or marketing directly.
“An individual’s CPNI can be shared with other telecommunications providers for network operating reasons,” wrote TechTarget’s Gavin Wright. “So, when the individual first signs up for phone service, this information is automatically shared by the phone provider to partner companies.”
Is your mobile Internet usage covered by CPNI laws? That’s less clear, as the CPNI rules were established before mobile phones and wireless Internet access were common. TechTarget’s CPNI primer explains:
“Under current U.S. law, cellphone use is only protected as CPNI when it is being used as a telephone. During this time, the company is acting as a telecommunications provider requiring CPNI rules. Internet use, websites visited, search history or apps used are not protected CPNI because the company is acting as an information services provider not subject to these laws.”
Hence, the carriers can share and sell this data because they’re not explicitly prohibited from doing so. All three major carriers say they take steps to anonymize the customer data they share, but researchers have shown it is not terribly difficult to de-anonymize supposedly anonymous web-browsing data.
“Your phone, and consequently your mobile provider, know a lot about you,” wrote Jack Morse for Mashable. “The places you go, apps you use, and the websites you visit potentially reveal all kinds of private information — e.g. religious beliefs, health conditions, travel plans, income level, and specific tastes in pornography. This should bother you.”
Happily, all of the U.S. carriers are required to offer customers ways to opt out of having data about how they use their devices shared with marketers. Here’s a look at some of the carrier-specific practices and opt-out options.
AT&T’s policy says it shares device or “ad ID”, combined with demographics including age range, gender, and ZIP code information with third parties which explicitly include advertisers, programmers, and networks, social media networks, analytics firms, ad networks and other similar companies that are involved in creating and delivering advertisements.
AT&T said the data exposed on 9 million customers was several years old, and mostly related to device upgrade eligibility. This may sound like the data went to just one of its partners who experienced a breach, but in all likelihood it also went to hundreds of AT&T’s partners.
AT&T’s CPNI opt-out page says it shares CPNI data with several of its affiliates, including WarnerMedia, DirecTV and Cricket Wireless. Until recently, AT&T also shared CPNI data with Xandr, whose privacy policy in turn explains that it shares data with hundreds of other advertising firms. Microsoft bought Xandr from AT&T last year.
According to the Electronic Privacy Information Center (EPIC), T-Mobile seems to be the only company out of the big three to extend to all customers the rights conferred by the California Consumer Privacy Act (CCPA).
EPIC says T-Mobile customer data sold to third parties uses another unique identifier called mobile advertising IDs or “MAIDs.” T-Mobile claims that MAIDs don’t directly identify consumers, but under the CCPA MAIDs are considered “personal information” that can be connected to IP addresses, mobile apps installed or used with the device, any video or content viewing information, and device activity and attributes.
T-Mobile customers can opt out by logging into their account and navigating to the profile page, then to “Privacy and Notifications.” From there, toggle off the options for “Use my data for analytics and reporting” and “Use my data to make ads more relevant to me.”
Verizon’s privacy policy says it does not sell information that personally identities customers (e.g., name, telephone number or email address), but it does allow third-party advertising companies to collect information about activity on Verizon websites and in Verizon apps, through MAIDs, pixels, web beacons and social network plugins.
According to Wired.com’s tutorial, Verizon users can opt out by logging into their Verizon account through a web browser or the My Verizon mobile app. From there, select the Account tab, then click Account Settings and Privacy Settings on the web. For the mobile app, click the gear icon in the upper right corner and then Manage Privacy Settings.
On the privacy preferences page, web users can choose “Don’t use” under the Custom Experience section. On the My Verizon app, toggle any green sliders to the left.
EPIC notes that all three major carriers say resetting the consumer’s device ID and/or clearing cookies in the browser will similarly reset any opt-out preferences (i.e., the customer will need to opt out again), and that blocking cookies by default may also block the opt-out cookie from being set.
T-Mobile says its opt out is device-specific and/or browser-specific. “In most cases, your opt-out choice will apply only to the specific device or browser on which it was made. You may need to separately opt out from your other devices and browsers.”
Both AT&T and Verizon offer opt-in programs that gather and share far more information, including device location, the phone numbers you call, and which sites you visit using your mobile and/or home Internet connection. AT&T calls this their Enhanced Relevant Advertising Program; Verizon’s is called Custom Experience Plus.
In 2021, multiple media outlets reported that some Verizon customers were being automatically enrolled in Custom Experience Plus — even after those customers had already opted out of the same program under its previous name — “Verizon Selects.”
If none of the above opt out options work for you, at a minimum you should be able to opt out of CPNI sharing by calling your carrier, or by visiting one of their stores.
Why should you opt out of sharing CPNI data? For starters, some of the nation’s largest wireless carriers don’t have a great track record in terms of protecting the sensitive information that you give them solely for the purposes of becoming a customer — let alone the information they collect about your use of their services after that point.
In January 2023, T-Mobile disclosed that someone stole data on 37 million customer accounts, including customer name, billing address, email, phone number, date of birth, T-Mobile account number and plan details. In August 2021, T-Mobile acknowledged that hackers made off with the names, dates of birth, Social Security numbers and driver’s license/ID information on more than 40 million current, former or prospective customers who applied for credit with the company.
Last summer, a cybercriminal began selling the names, email addresses, phone numbers, SSNs and dates of birth on 23 million Americans. An exhaustive analysis of the data strongly suggested it all belonged to customers of one AT&T company or another. AT&T stopped short of saying the data wasn’t theirs, but said the records did not appear to have come from its systems and may be tied to a previous data incident at another company.
However frequently the carriers may alert consumers about CPNI breaches, it’s probably nowhere near often enough. Currently, the carriers are required to report a consumer CPNI breach only in cases “when a person, without authorization or exceeding authorization, has intentionally gained access to, used or disclosed CPNI.”
But that definition of breach was crafted eons ago, back when the primary way CPNI was exposed was through “pretexting,” such when the phone company’s employees are tricked into giving away protected customer data.
In January, regulators at the U.S. Federal Communications Commission (FCC) proposed amending the definition of “breach” to include things like inadvertent disclosure — such as when companies expose CPNI data on a poorly-secured server in the cloud. The FCC is accepting public comments on the matter until March 24, 2023.
While it’s true that the leak of CPNI data does not involve sensitive information like Social Security or credit card numbers, one thing AT&T’s breach notice doesn’t mention is that CPNI data — such as balances and payments made — can be abused by fraudsters to make scam emails and text messages more believable when they’re trying to impersonate AT&T and phish AT&T customers.
The other problem with letting companies share or sell your CPNI data is that the wireless carriers can change their privacy policies at any time, and you are assumed to be okay with those changes as long as you keep using their services.
For example, location data from your wireless device is most definitely CPNI, and yet until very recently all of the major carriers sold their customers’ real-time location data to third party data brokers without customer consent.
What was their punishment? In 2020, the FCC proposed fines totaling $208 million against all of the major carriers for selling their customers’ real-time location data. If that sounds like a lot of money, consider that all of the major wireless providers reported tens of billions of dollars in revenue last year (e.g., Verizon’s consumer revenue alone was more than $100 billion last year).
If the United States had federal privacy laws that were at all consumer-friendly and relevant to today’s digital economy, this kind of data collection and sharing would always be opt-in by default. In such a world, the enormously profitable wireless industry would likely be forced to offer clear financial incentives to customers who choose to share this information.
But until that day arrives, understand that the carriers can change their data collection and sharing policies when it suits them. And regardless of whether you actually read any notices about changes to their privacy policies, you will have agreed to those changes as long as you continue using their service.
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Three different cybercriminal groups claimed access to internal networks at communications giant T-Mobile in more than 100 separate incidents throughout 2022, new data suggests. In each case, the goal of the attackers was the same: Phish T-Mobile employees for access to internal company tools, and then convert that access into a cybercrime service that could be hired to divert any T-Mobile user’s text messages and phone calls to another device.
The conclusions above are based on an extensive analysis of Telegram chat logs from three distinct cybercrime groups or actors that have been identified by security researchers as particularly active in and effective at “SIM-swapping,” which involves temporarily seizing control over a target’s mobile phone number.
Countless websites and online services use SMS text messages for both password resets and multi-factor authentication. This means that stealing someone’s phone number often can let cybercriminals hijack the target’s entire digital life in short order — including access to any financial, email and social media accounts tied to that phone number.
All three SIM-swapping entities that were tracked for this story remain active in 2023, and they all conduct business in open channels on the instant messaging platform Telegram. KrebsOnSecurity is not naming those channels or groups here because they will simply migrate to more private servers if exposed publicly, and for now those servers remain a useful source of intelligence about their activities.
Each advertises their claimed access to T-Mobile systems in a similar way. At a minimum, every SIM-swapping opportunity is announced with a brief “Tmobile up!” or “Tmo up!” message to channel participants. Other information in the announcements includes the price for a single SIM-swap request, and the handle of the person who takes the payment and information about the targeted subscriber.
The information required from the customer of the SIM-swapping service includes the target’s phone number, and the serial number tied to the new SIM card that will be used to receive text messages and phone calls from the hijacked phone number.
Initially, the goal of this project was to count how many times each entity claimed access to T-Mobile throughout 2022, by cataloging the various “Tmo up!” posts from each day and working backwards from Dec. 31, 2022.
But by the time we got to claims made in the middle of May 2022, completing the rest of the year’s timeline seemed unnecessary. The tally shows that in the last seven-and-a-half months of 2022, these groups collectively made SIM-swapping claims against T-Mobile on 104 separate days — often with multiple groups claiming access on the same days.
The 104 days in the latter half of 2022 in which different known SIM-swapping groups claimed access to T-Mobile employee tools.
KrebsOnSecurity shared a large amount of data gathered for this story with T-Mobile. The company declined to confirm or deny any of these claimed intrusions. But in a written statement, T-Mobile said this type of activity affects the entire wireless industry.
“And we are constantly working to fight against it,” the statement reads. “We have continued to drive enhancements that further protect against unauthorized access, including enhancing multi-factor authentication controls, hardening environments, limiting access to data, apps or services, and more. We are also focused on gathering threat intelligence data, like what you have shared, to help further strengthen these ongoing efforts.”
While it is true that each of these cybercriminal actors periodically offer SIM-swapping services for other mobile phone providers — including AT&T, Verizon and smaller carriers — those solicitations appear far less frequently in these group chats than T-Mobile swap offers. And when those offers do materialize, they are considerably more expensive.
The prices advertised for a SIM-swap against T-Mobile customers in the latter half of 2022 ranged between USD $1,000 and $1,500, while SIM-swaps offered against AT&T and Verizon customers often cost well more than twice that amount.
To be clear, KrebsOnSecurity is not aware of specific SIM-swapping incidents tied to any of these breach claims. However, the vast majority of advertisements for SIM-swapping claims against T-Mobile tracked in this story had two things in common that set them apart from random SIM-swapping ads on Telegram.
First, they included an offer to use a mutually trusted “middleman” or escrow provider for the transaction (to protect either party from getting scammed). More importantly, the cybercriminal handles that were posting ads for SIM-swapping opportunities from these groups generally did so on a daily or near-daily basis — often teasing their upcoming swap events in the hours before posting a “Tmo up!” message announcement.
In other words, if the crooks offering these SIM-swapping services were ripping off their customers or claiming to have access that they didn’t, this would be almost immediately obvious from the responses of the more seasoned and serious cybercriminals in the same chat channel.
There are plenty of people on Telegram claiming to have SIM-swap access at major telecommunications firms, but a great many such offers are simply four-figure scams, and any pretenders on this front are soon identified and banned (if not worse).
One of the groups that reliably posted “Tmo up!” messages to announce SIM-swap availability against T-Mobile customers also reliably posted “Tmo down!” follow-up messages announcing exactly when their claimed access to T-Mobile employee tools was discovered and revoked by the mobile giant.
A review of the timestamps associated with this group’s incessant “Tmo up” and “Tmo down” posts indicates that while their claimed access to employee tools usually lasted less than an hour, in some cases that access apparently went undiscovered for several hours or even days.
How could these SIM-swapping groups be gaining access to T-Mobile’s network as frequently as they claim? Peppered throughout the daily chit-chat on their Telegram channels are solicitations for people urgently needed to serve as “callers,” or those who can be hired to social engineer employees over the phone into navigating to a phishing website and entering their employee credentials.
Allison Nixon is chief research officer for the New York City-based cybersecurity firm Unit 221B. Nixon said these SIM-swapping groups will typically call employees on their mobile devices, pretend to be someone from the company’s IT department, and then try to get the person on the other end of the line to visit a phishing website that mimics the company’s employee login page.
Nixon argues that many people in the security community tend to discount the threat from voice phishing attacks as somehow “low tech” and “low probability” threats.
“I see it as not low-tech at all, because there are a lot of moving parts to phishing these days,” Nixon said. “You have the caller who has the employee on the line, and the person operating the phish kit who needs to spin it up and down fast enough so that it doesn’t get flagged by security companies. Then they have to get the employee on that phishing site and steal their credentials.”
In addition, she said, often there will be yet another co-conspirator whose job it is to use the stolen credentials and log into employee tools. That person may also need to figure out how to make their device pass “posture checks,” a form of device authentication that some companies use to verify that each login is coming only from employer-issued phones or laptops.
For aspiring criminals with little experience in scam calling, there are plenty of sample call transcripts available on these Telegram chat channels that walk one through how to impersonate an IT technician at the targeted company — and how to respond to pushback or skepticism from the employee. Here’s a snippet from one such tutorial that appeared recently in one of the SIM-swapping channels:
“Hello this is James calling from Metro IT department, how’s your day today?”
(yea im doing good, how r u)
i’m doing great, thank you for asking
i’m calling in regards to a ticket we got last week from you guys, saying you guys were having issues with the network connectivity which also interfered with [Microsoft] Edge, not letting you sign in or disconnecting you randomly. We haven’t received any updates to this ticket ever since it was created so that’s why I’m calling in just to see if there’s still an issue or not….”
The TMO UP data referenced above, combined with comments from the SIM-swappers themselves, indicate that while many of their claimed accesses to T-Mobile tools in the middle of 2022 lasted hours on end, both the frequency and duration of these events began to steadily decrease as the year wore on.
T-Mobile declined to discuss what it may have done to combat these apparent intrusions last year. However, one of the groups began to complain loudly in late October 2022 that T-Mobile must have been doing something that was causing their phished access to employee tools to die very soon after they obtained it.
One group even remarked that they suspected T-Mobile’s security team had begun monitoring their chats.
Indeed, the timestamps associated with one group’s TMO UP/TMO DOWN notices show that their claimed access was often limited to less than 15 minutes throughout November and December of 2022.
Whatever the reason, the calendar graphic above clearly shows that the frequency of claimed access to T-Mobile decreased significantly across all three SIM-swapping groups in the waning weeks of 2022.
T-Mobile US reported revenues of nearly $80 billion last year. It currently employs more than 71,000 people in the United States, any one of whom can be a target for these phishers.
T-Mobile declined to answer questions about what it may be doing to beef up employee authentication. But Nicholas Weaver, a researcher and lecturer at University of California, Berkeley’s International Computer Science Institute, said T-Mobile and all the major wireless providers should be requiring employees to use physical security keys for that second factor when logging into company resources.
A U2F device made by Yubikey.
“These breaches should not happen,” Weaver said. “Because T-Mobile should have long ago issued all employees security keys and switched to security keys for the second factor. And because security keys provably block this style of attack.”
The most commonly used security keys are inexpensive USB-based devices. A security key implements a form of multi-factor authentication known as Universal 2nd Factor (U2F), which allows the user to complete the login process simply by inserting the USB key and pressing a button on the device. The key works without the need for any special software drivers.
The allure of U2F devices for multi-factor authentication is that even if an employee who has enrolled a security key for authentication tries to log in at an impostor site, the company’s systems simply refuse to request the security key if the user isn’t on their employer’s legitimate website, and the login attempt fails. Thus, the second factor cannot be phished, either over the phone or Internet.
Nixon said one confounding aspect of SIM-swapping is that these criminal groups tend to recruit teenagers to do their dirty work.
“A huge reason this problem has been allowed to spiral out of control is because children play such a prominent role in this form of breach,” Nixon said.
Nixon said SIM-swapping groups often advertise low-level jobs on places like Roblox and Minecraft, online games that are extremely popular with young adolescent males.
“Statistically speaking, that kind of recruiting is going to produce a lot of people who are underage,” she said. “They recruit children because they’re naive, you can get more out of them, and they have legal protections that other people over 18 don’t have.”
For example, she said, even when underage SIM-swappers are arrested, the offenders tend to go right back to committing the same crimes as soon as they’re released.
In January 2023, T-Mobile disclosed that a “bad actor” stole records on roughly 37 million current customers, including their name, billing address, email, phone number, date of birth, and T-Mobile account number.
In August 2021, T-Mobile acknowledged that hackers made off with the names, dates of birth, Social Security numbers and driver’s license/ID information on more than 40 million current, former or prospective customers who applied for credit with the company. That breach came to light after a hacker began selling the records on a cybercrime forum.
In the shadow of such mega-breaches, any damage from the continuous attacks by these SIM-swapping groups can seem insignificant by comparison. But Nixon says it’s a mistake to dismiss SIM-swapping as a low volume problem.
“Logistically, you may only be able to get a few dozen or a hundred SIM-swaps in a day, but you can pick any customer you want across their entire customer base,” she said. “Just because a targeted account takeover is low volume doesn’t mean it’s low risk. These guys have crews that go and identify people who are high net worth individuals and who have a lot to lose.”
Nixon said another aspect of SIM-swapping that causes cybersecurity defenders to dismiss the threat from these groups is the perception that they are full of low-skilled “script kiddies,” a derisive term used to describe novice hackers who rely mainly on point-and-click hacking tools.
“They underestimate these actors and say this person isn’t technically sophisticated,” she said. “But if you’re rolling around in millions worth of stolen crypto currency, you can buy that sophistication. I know for a fact some of these compromises were at the hands of these ‘script kiddies,’ but they’re not ripping off other people’s scripts so much as hiring people to make scripts for them. And they don’t care what gets the job done, as long as they get to steal the money.”
T-Mobile today disclosed a data breach affecting tens of millions of customer accounts, its second major data exposure in as many years. In a filing with federal regulators, T-Mobile said an investigation determined that someone abused its systems to harvest subscriber data tied to approximately 37 million current customer accounts.
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In a filing today with the U.S. Securities and Exchange Commission, T-Mobile said a “bad actor” abused an application programming interface (API) to hoover up data on roughly 37 million current postpaid and prepaid customer accounts. The data stolen included customer name, billing address, email, phone number, date of birth, T-Mobile account number, as well as information on the number of customer lines and plan features.
APIs are essentially instructions that allow applications to access data and interact with web databases. But left improperly secured, these APIs can be leveraged by malicious actors to mass-harvest information stored in those databases. In October, mobile provider Optus disclosed that hackers abused a poorly secured API to steal data on 10 million customers in Australia.
T-Mobile said it first learned of the incident on Jan. 5, 2023, and that an investigation determined the bad actor started abusing the API beginning around Nov. 25, 2022. The company says it is in the process of notifying affected customers, and that no customer payment card data, passwords, Social Security numbers, driver’s license or other government ID numbers were exposed.
In August 2021, T-Mobile acknowledged that hackers made off with the names, dates of birth, Social Security numbers and driver’s license/ID information on more than 40 million current, former or prospective customers who applied for credit with the company. That breach came to light after a hacker began selling the records on a cybercrime forum.
Last year, T-Mobile agreed to pay $500 million to settle all class action lawsuits stemming from the 2021 breach. The company pledged to spend $150 million of that money toward beefing up its own cybersecurity.
In its filing with the SEC, T-Mobile suggested it was going to take years to fully realize the benefits of those cybersecurity improvements, even as it claimed that protecting customer data remains a top priority.
“As we have previously disclosed, in 2021, we commenced a substantial multi-year investment working with leading external cybersecurity experts to enhance our cybersecurity capabilities and transform our approach to cybersecurity,” the filing reads. “We have made substantial progress to date, and protecting our customers’ data remains a top priority.”
Despite this being the second major customer data spill in as many years, T-Mobile told the SEC the company does not expect this latest breach to have a material impact on its operations.
While that may seem like a daring thing to say in a data breach disclosure affecting a significant portion of your active customer base, consider that T-Mobile reported revenues of nearly $20 billion in the third quarter of 2022 alone. In that context, a few hundred million dollars every couple of years to make the class action lawyers go away is a drop in the bucket.
The settlement related to the 2021 breach says T-Mobile will make $350 million available to customers who file a claim. But here’s the catch: If you were affected by that 2021 breach and you haven’t filed a claim yet, please know that you have only three more days to do that.
If you were a T-Mobile customer affected by the 2021 incident, it is likely that T-Mobile has already made several efforts to notify you of your eligibility to file a claim, which includes a payout of at least $25, with the possibility of more for those who can document direct costs associated with the breach. OpenClassActions.com says the filing deadline is Jan. 23, 2023.
“If you opt for a cash payment you will receive an estimated $25.00,” the site explains. “If you reside in California, you will receive an estimated $100.00. Out of pocket losses can be reimbursed for up to $25,000.00. The amount that you claim from T-Mobile will be determined by the class action administrator based on how many people file a legitimate and timely claim form.”
There are currently no signs that hackers are selling this latest data haul from T-Mobile, but if the past is any teacher much of it will wind up posted online soon. It is a safe bet that scammers will use some of this information to target T-Mobile users with phishing messages, account takeovers and harassment.
T-Mobile customers should fully expect to see phishers taking advantage of public concern over the breach to impersonate the company — and possibly even send messages that include the recipient’s compromised account details to make the communications look more legitimate.
Data stolen and exposed in this breach may also be used for identity theft. Credit monitoring and ID theft protection services can help you recover from having your identity stolen, but most will do nothing to stop the ID theft from happening. If you want the maximum control over who should be able to view your credit or grant new lines of credit in your name, then a security freeze is your best option.
Regardless of which mobile provider you patronize, please consider removing your phone number from as many online accounts as you can. Many online services require you to provide a phone number upon registering an account, but in many cases that number can be removed from your profile afterwards.
Why do I suggest this? Many online services allow users to reset their passwords just by clicking a link sent via SMS, and this unfortunately widespread practice has turned mobile phone numbers into de facto identity documents. Which means losing control over your phone number thanks to an unauthorized SIM swap or mobile number port-out, divorce, job termination or financial crisis can be devastating.
Phishers are enjoying remarkable success using text messages to steal remote access credentials and one-time passcodes from employees at some of the world’s largest technology companies and customer support firms. A recent spate of SMS phishing attacks from one cybercriminal group has spawned a flurry of breach disclosures from affected companies, which are all struggling to combat the same lingering security threat: The ability of scammers to interact directly with employees through their mobile devices.
In mid-June 2022, a flood of SMS phishing messages began targeting employees at commercial staffing firms that provide customer support and outsourcing to thousands of companies. The missives asked users to click a link and log in at a phishing page that mimicked their employer’s Okta authentication page. Those who submitted credentials were then prompted to provide the one-time password needed for multi-factor authentication.
The phishers behind this scheme used newly-registered domains that often included the name of the target company, and sent text messages urging employees to click on links to these domains to view information about a pending change in their work schedule.
The phishing sites leveraged a Telegram instant message bot to forward any submitted credentials in real-time, allowing the attackers to use the phished username, password and one-time code to log in as that employee at the real employer website. But because of the way the bot was configured, it was possible for security researchers to capture the information being sent by victims to the public Telegram server.
This data trove was first reported by security researchers at Singapore-based Group-IB, which dubbed the campaign “0ktapus” for the attackers targeting organizations using identity management tools from Okta.com.
“This case is of interest because despite using low-skill methods it was able to compromise a large number of well-known organizations,” Group-IB wrote. “Furthermore, once the attackers compromised an organization they were quickly able to pivot and launch subsequent supply chain attacks, indicating that the attack was planned carefully in advance.”
It’s not clear how many of these phishing text messages were sent out, but the Telegram bot data reviewed by KrebsOnSecurity shows they generated nearly 10,000 replies over approximately two months of sporadic SMS phishing attacks targeting more than a hundred companies.
A great many responses came from those who were apparently wise to the scheme, as evidenced by the hundreds of hostile replies that included profanity or insults aimed at the phishers: The very first reply recorded in the Telegram bot data came from one such employee, who responded with the username “havefuninjail.”
Still, thousands replied with what appear to be legitimate credentials — many of them including one-time codes needed for multi-factor authentication. On July 20, the attackers turned their sights on internet infrastructure giant Cloudflare.com, and the intercepted credentials show at least three employees fell for the scam.
Image: Cloudflare.com
In a blog post earlier this month, Cloudflare said it detected the account takeovers and that no Cloudflare systems were compromised. Cloudflare said it does not rely on one-time passcodes as a second factor, so there was nothing to provide to the attackers. But Cloudflare said it wanted to call attention to the phishing attacks because they would probably work against most other companies.
“This was a sophisticated attack targeting employees and systems in such a way that we believe most organizations would be likely to be breached,” Cloudflare CEO Matthew Prince wrote. “On July 20, 2022, the Cloudflare Security team received reports of employees receiving legitimate-looking text messages pointing to what appeared to be a Cloudflare Okta login page. The messages began at 2022-07-20 22:50 UTC. Over the course of less than 1 minute, at least 76 employees received text messages on their personal and work phones. Some messages were also sent to the employees family members.”
On three separate occasions, the phishers targeted employees at Twilio.com, a San Francisco based company that provides services for making and receiving text messages and phone calls. It’s unclear how many Twilio employees received the SMS phishes, but the data suggest at least four Twilio employees responded to a spate of SMS phishing attempts on July 27, Aug. 2, and Aug. 7.
On that last date, Twilio disclosed that on Aug. 4 it became aware of unauthorized access to information related to a limited number of Twilio customer accounts through a sophisticated social engineering attack designed to steal employee credentials.
“This broad based attack against our employee base succeeded in fooling some employees into providing their credentials,” Twilio said. “The attackers then used the stolen credentials to gain access to some of our internal systems, where they were able to access certain customer data.”
That “certain customer data” included information on roughly 1,900 users of the secure messaging app Signal, which relied on Twilio to provide phone number verification services. In its disclosure on the incident, Signal said that with their access to Twilio’s internal tools the attackers were able to re-register those users’ phone numbers to another device.
On Aug. 25, food delivery service DoorDash disclosed that a “sophisticated phishing attack” on a third-party vendor allowed attackers to gain access to some of DoorDash’s internal company tools. DoorDash said intruders stole information on a “small percentage” of users that have since been notified. TechCrunch reported last week that the incident was linked to the same phishing campaign that targeted Twilio.
This phishing gang apparently had great success targeting employees of all the major mobile wireless providers, but most especially T-Mobile. Between July 10 and July 16, dozens of T-Mobile employees fell for the phishing messages and provided their remote access credentials.
“Credential theft continues to be an ongoing issue in our industry as wireless providers are constantly battling bad actors that are focused on finding new ways to pursue illegal activities like this,” T-Mobile said in a statement. “Our tools and teams worked as designed to quickly identify and respond to this large-scale smishing attack earlier this year that targeted many companies. We continue to work to prevent these types of attacks and will continue to evolve and improve our approach.”
This same group saw hundreds of responses from employees at some of the largest customer support and staffing firms, including Teleperformanceusa.com, Sitel.com and Sykes.com. Teleperformance did not respond to requests for comment. KrebsOnSecurity did hear from Christopher Knauer, global chief security officer at Sitel Group, the customer support giant that recently acquired Sykes. Knauer said the attacks leveraged newly-registered domains and asked employees to approve upcoming changes to their work schedules.
Image: Group-IB.
Knauer said the attackers set up the phishing domains just minutes in advance of spamming links to those domains in phony SMS alerts to targeted employees. He said such tactics largely sidestep automated alerts generated by companies that monitor brand names for signs of new phishing domains being registered.
“They were using the domains as soon as they became available,” Knauer said. “The alerting services don’t often let you know until 24 hours after a domain has been registered.”
On July 28 and again on Aug. 7, several employees at email delivery firm Mailchimp provided their remote access credentials to this phishing group. According to an Aug. 12 blog post, the attackers used their access to Mailchimp employee accounts to steal data from 214 customers involved in cryptocurrency and finance.
On Aug. 15, the hosting company DigitalOcean published a blog post saying it had severed ties with MailChimp after its Mailchimp account was compromised. DigitalOcean said the MailChimp incident resulted in a “very small number” of DigitalOcean customers experiencing attempted compromises of their accounts through password resets.
According to interviews with multiple companies hit by the group, the attackers are mostly interested in stealing access to cryptocurrency, and to companies that manage communications with people interested in cryptocurrency investing. In an Aug. 3 blog post from email and SMS marketing firm Klaviyo.com, the company’s CEO recounted how the phishers gained access to the company’s internal tools, and used that to download information on 38 crypto-related accounts.
A flow chart of the attacks by the SMS phishing group known as 0ktapus and ScatterSwine. Image: Amitai Cohen for Wiz.io. twitter.com/amitaico.
The ubiquity of mobile phones became a lifeline for many companies trying to manage their remote employees throughout the Coronavirus pandemic. But these same mobile devices are fast becoming a liability for organizations that use them for phishable forms of multi-factor authentication, such as one-time codes generated by a mobile app or delivered via SMS.
Because as we can see from the success of this phishing group, this type of data extraction is now being massively automated, and employee authentication compromises can quickly lead to security and privacy risks for the employer’s partners or for anyone in their supply chain.
Unfortunately, a great many companies still rely on SMS for employee multi-factor authentication. According to a report this year from Okta, 47 percent of workforce customers deploy SMS and voice factors for multi-factor authentication. That’s down from 53 percent that did so in 2018, Okta found.
Some companies (like Knauer’s Sitel) have taken to requiring that all remote access to internal networks be managed through work-issued laptops and/or mobile devices, which are loaded with custom profiles that can’t be accessed through other devices.
Others are moving away from SMS and one-time code apps and toward requiring employees to use physical FIDO multi-factor authentication devices such as security keys, which can neutralize phishing attacks because any stolen credentials can’t be used unless the phishers also have physical access to the user’s security key or mobile device.
This came in handy for Twitter, which announced last year that it was moving all of its employees to using security keys, and/or biometric authentication via their mobile device. The phishers’ Telegram bot reported that on June 16, 2022, five employees at Twitter gave away their work credentials. In response to questions from KrebsOnSecurity, Twitter confirmed several employees were relieved of their employee usernames and passwords, but that its security key requirement prevented the phishers from abusing that information.
Twitter accelerated its plans to improve employee authentication following the July 2020 security incident, wherein several employees were phished and relieved of credentials for Twitter’s internal tools. In that intrusion, the attackers used Twitter’s tools to hijack accounts for some of the world’s most recognizable public figures, executives and celebrities — forcing those accounts to tweet out links to bitcoin scams.
“Security keys can differentiate legitimate sites from malicious ones and block phishing attempts that SMS 2FA or one-time password (OTP) verification codes would not,” Twitter said in an Oct. 2021 post about the change. “To deploy security keys internally at Twitter, we migrated from a variety of phishable 2FA methods to using security keys as our only supported 2FA method on internal systems.”
Update, 6:02 p.m. ET: Clarified that Cloudflare does not rely on TOTP (one-time multi-factor authentication codes) as a second factor for employee authentication.
Image: Shutterstock.
A cybersecurity firm says it has intercepted a large, unique stolen data set containing the names, addresses, email addresses, phone numbers, Social Security Numbers and dates of birth on nearly 23 million Americans. The firm’s analysis of the data suggests it corresponds to current and former customers of AT&T. The telecommunications giant stopped short of saying the data wasn’t theirs, but it maintains the records do not appear to have come from its systems and may be tied to a previous data incident at another company.
Milwaukee-based cybersecurity consultancy Hold Security said it intercepted a 1.6 gigabyte compressed file on a popular dark web file-sharing site. The largest item in the archive is a 3.6 gigabyte file called “dbfull,” and it contains 28.5 million records, including 22.8 million unique email addresses and 23 million unique SSNs. There are no passwords in the database.
Hold Security founder Alex Holden said a number of patterns in the data suggest it relates to AT&T customers. For starters, email addresses ending in “att.net” accounted for 13.7 percent of all addresses in the database, with addresses from SBCGLobal.net and Bellsouth.net — both AT&T companies — making up another seven percent. In contrast, Gmail users made up more than 30 percent of the data set, with Yahoo addresses accounting for 24 percent. More than 10,000 entries in the database list “none@att.com” in the email field.
Hold Security found these email domains account for 87% of all domains in the data set. Nearly 21% belonged to AT&T customers.
Holden’s team also examined the number of email records that included an alias in the username portion of the email, and found 293 email addresses with plus addressing. Of those, 232 included an alias that indicated the customer had signed up at some AT&T property; 190 of the aliased email addresses were “+att@”; 42 were “+uverse@,” an oddly specific reference to an AT&T entity that included broadband Internet. In September 2016, AT&T rebranded U-verse as AT&T Internet.
According to its website, AT&T Internet is offered in 21 states, including Alabama, Arkansas, California, Florida, Georgia, Indiana, Kansas, Kentucky, Louisiana, Michigan, Missouri, Nevada, North Carolina, Ohio, Oklahoma, Tennessee, Texas and Wisconsin. Nearly all of the records in the database that contain a state designation corresponded to those 21 states; all other states made up just 1.64 percent of the records, Hold Security found.
Image: Hold Security.
The vast majority of records in this database belong to consumers, but almost 13,000 of the entries are for corporate entities. Holden said 387 of those corporate names started with “ATT,” with various entries like “ATT PVT XLOW” appearing 81 times. And most of the addresses for these entities are AT&T corporate offices.
How old is this data? One clue may be in the dates of birth exposed in this database. There are very few records in this file with dates of birth after 2000.
“Based on these statistics, we see that the last significant number of subscribers born in March of 2000,” Holden told KrebsOnSecurity, noting that AT&T requires new account holders to be 18 years of age or older. “Therefore, it makes sense that the dataset was likely created close to March of 2018.”
There was also this anomaly: Holden said one of his analysts is an AT&T customer with a 13-letter last name, and that her AT&T bill has always had the same unique misspelling of her surname (they added yet another letter). He said the analyst’s name is identically misspelled in this database.
KrebsOnSecurity shared the large data set with AT&T, as well as Hold Security’s analysis of it. AT&T ultimately declined to say whether all of the people in the database are or were at some point AT&T customers. The company said the data appears to be several years old, and that “it’s not immediately possible to determine the percentage that may be customers.”
“This information does not appear to have come from our systems,” AT&T said in a written statement. “It may be tied to a previous data incident at another company. It is unfortunate that data can continue to surface over several years on the dark web. However, customers often receive notices after such incidents, and advice for ID theft is consistent and can be found online.”
The company declined to elaborate on what they meant by “a previous data incident at another company.”
But it seems likely that this database is related to one that went up for sale on a hacker forum on August 19, 2021. That auction ran with the title “AT&T Database +70M (SSN/DOB),” and was offered by ShinyHunters, a well-known threat actor with a long history of compromising websites and developer repositories to steal credentials or API keys.
Image: BleepingComputer
ShinyHunters established the starting price for the auction at $200,000, but set the “flash” or “buy it now” price at $1 million. The auction also included a small sampling of the stolen information, but that sample is no longer available. The hacker forum where the ShinyHunters sales thread existed was seized by the FBI in April, and its alleged administrator arrested.
But cached copies of the auction, as recorded by cyber intelligence firm Intel 471, show ShinyHunters received bids of up to $230,000 for the entire database before they suspended the sale.
“This thread has been deleted several times,” ShinyHunters wrote in their auction discussion on Sept. 6, 2021. “Therefore, the auction is suspended. AT&T will be available on WHM as soon as they accept new vendors.”
The WHM initialism was a reference to the White House Market, a dark web marketplace that shut down in October 2021.
“In many cases, when a database is not sold, ShinyHunters will release it for free on hacker forums,” wrote BleepingComputer’s Lawrence Abrams, who broke the news of the auction last year and confronted AT&T about the hackers’ claims.
AT&T gave Abrams a similar statement, saying the data didn’t come from their systems.
“When asked whether the data may have come from a third-party partner, AT&T chose not to speculate,” Abrams wrote. “‘Given this information did not come from us, we can’t speculate on where it came from or whether it is valid,'” AT&T told BleepingComputer.
Asked to respond to AT&T’s denial, ShinyHunters told BleepingComputer at the time, “I don’t care if they don’t admit. I’m just selling.”
On June 1, 2022, a 21-year-old Frenchman was arrested in Morocco for allegedly being a member of ShinyHunters. Databreaches.net reports the defendant was arrested on an Interpol “Red Notice” at the request of a U.S. federal prosecutor from Washington state.
Databreaches.net suggests the warrant could be tied to a ShinyHunters theft in May 2020, when the group announced they had exfiltrated 500 GB of Microsoft’s source code from Microsoft’s private GitHub repositories.
“Researchers assess that Shiny Hunters gained access to roughly 1,200 private repositories around March 28, 2020, which have since been secured,” reads a May 2020 alert posted by the New Jersey Cybersecurity & Communications Integration Cell, a component within the New Jersey Office of Homeland Security and Preparedness.
“Though the breach was largely dismissed as insignificant, some images of the directory listing appear to contain source code for Azure, Office, and some Windows runtimes, and concerns have been raised regarding access to private API keys or passwords that may have been mistakenly included in some private repositories,” the alert continues. “Additionally, Shiny Hunters is flooding dark web marketplaces with breached databases.”
Last month, T-Mobile agreed to pay $350 million to settle a consolidated class action lawsuit over a breach in 2021 that affected 40 million current and former customers. The breach came to light on Aug. 16, 2021, when someone starting selling tens of millions of SSN/DOB records from T-Mobile on the same hacker forum where the ShinyHunters would post their auction for the claimed AT&T database just three days later.
T-Mobile has not disclosed many details about the “how” of last year’s breach, but it said the intruder(s) “leveraged their knowledge of technical systems, along with specialized tools and capabilities, to gain access to our testing environments and then used brute force attacks and other methods to make their way into other IT servers that included customer data.”
A sales thread tied to the stolen T-Mobile customer data.
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