Hackers Claim They Breached T-Mobile More Than 100 Times in 2022

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.

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.”

TMO UP!

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.

TMO TOOLS

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….”

TMO DOWN!

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.

SECURITY KEYS

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.

“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.

THE ROLE OF MINORS IN SIM-SWAPPING

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.”

Thinking of Hiring or Running a Booter Service? Think Again.

Most people who operate DDoS-for-hire businesses attempt to hide their true identities and location. Proprietors of these so-called “booter” or “stresser” services — designed to knock websites and users offline — have long operated in a legally murky area of cybercrime law. But until recently, their biggest concern wasn’t avoiding capture or shutdown by the feds: It was minimizing harassment from unhappy customers or victims, and insulating themselves against incessant attacks from competing DDoS-for-hire services.

And then there are booter store operators like John Dobbs, a 32-year-old computer science graduate student living in Honolulu, Hawaii. For at least a decade until late last year, Dobbs openly operated IPStresser[.]com, a popular and powerful attack-for-hire service that he registered with the state of Hawaii using his real name and address. Likewise, the domain was registered in Dobbs’s name and hometown in Pennsylvania.

The only work experience Dobbs listed on his resume was as a freelance developer from 2013 to the present day. Dobbs’s resume doesn’t name his booter service, but in it he brags about maintaining websites with half a million page views daily, and “designing server deployments for performance, high-availability and security.”

In December 2022, the U.S. Department of Justice seized Dobbs’s IPStresser website and charged him with one count of aiding and abetting computer intrusions. Prosecutors say his service attracted more than two million registered users, and was responsible for launching a staggering 30 million distinct DDoS attacks.

The government seized four-dozen booter domains, and criminally charged Dobbs and five other U.S. men for allegedly operating stresser services. This was the Justice Department’s second such mass takedown targeting DDoS-for-hire services and their accused operators. In 2018, the feds seized 15 stresser sites, and levied cybercrime charges against three men for their operation of booter services.

Many accused stresser site operators have pleaded guilty over the years after being hit with federal criminal charges. But the government’s core claim — that operating a booter site is a violation of U.S. computer crime laws — wasn’t properly tested in the courts until September 2021.

That was when a jury handed down a guilty verdict against Matthew Gatrel, a then 32-year-old St. Charles, Ill. man charged in the government’s first 2018 mass booter bust-up. Despite admitting to FBI agents that he ran two booter services (and turning over plenty of incriminating evidence in the process), Gatrel opted to take his case to trial, defended the entire time by court-appointed attorneys.

Prosecutors said Gatrel’s booter services — downthem[.]org and ampnode[.]com — helped some 2,000 paying customers launch debilitating digital assaults on more than 20,000 targets, including many government, banking, university and gaming websites.

Gatrel was convicted on all three charges of violating the Computer Fraud and Abuse Act, including conspiracy to commit unauthorized impairment of a protected computer, conspiracy to commit wire fraud, and unauthorized impairment of a protected computer. He was sentenced to two years in prison.

Now, it appears Dobbs is also planning to take his chances with a jury. On Jan. 4, Dobbs entered a plea of not guilty. Neither Dobbs nor his court-appointed attorney responded to requests for comment.

But as it happens, Dobbs himself provided some perspective on his thinking in an email exchange with KrebsOnSecurity back in 2020. I’d reached out to Dobbs because it was obvious he didn’t mind if people knew he operated one of the world’s most popular DDoS-for-hire sites, and I was genuinely curious why he was so unafraid of getting raided by the feds.

“Yes, I am the owner of the domain you listed, however you are not authorized to post an article containing said domain name, my name or this email address without my prior written permission,” Dobbs replied to my initial outreach on March 10, 2020 using his email address from the University of Hawaii at Manoa.

A few hours later, I received more strident instructions from Dobbs, this time via his official email address at ipstresser[.]com.

“I will state again for absolute clarity, you are not authorized to post an article containing ipstresser.com, my name, my GitHub profile and/or my hawaii.edu email address,” Dobbs wrote, as if taking dictation from a lawyer who doesn’t understand how the media works.

When pressed for particulars on his business, Dobbs replied that the number of IPStresser customers was “privileged information,” and said he didn’t even advertise the service. When asked whether he was concerned that many of his competitors were by then serving jail time for operating similar booter services, Dobbs maintained that the way he’d set up the business insulated him from any liability.

“I have been aware of the recent law enforcement actions against other operators of stress testing services,” Dobbs explained. “I cannot speak to the actions of these other services, but we take proactive measures to prevent misuse of our service and we work with law enforcement agencies regarding any reported abuse of our service.”

What were those proactive measures? In a 2015 interview with ZDNet France, Dobbs asserted that he was immune from liability because his clients all had to submit a digital signature attesting that they wouldn’t use the site for illegal purposes.

“Our terms of use are a legal document that protects us, among other things, from certain legal consequences,” Dobbs told ZDNet. “Most other sites are satisfied with a simple checkbox, but we ask for a digital signature in order to imply real consent from our customers.”

Dobbs told KrebsOnSecurity his service didn’t generate much of a profit, but rather that he was motivated by “filling a legitimate need.”

“My reason for offering the service is to provide the ability to test network security measures before someone with malicious intent attacks said network and causes downtime,” he said. “Sure, some people see only the negatives, but there is a long list of companies I have worked with over the years who would say my service is a godsend and has helped them prevent tens of thousands of dollars in downtime resulting from a malicious attack.”

“I do not believe that providing such a service is illegal, assuming proper due diligence to prevent malicious use of the service, as is the case for IPstresser[.]com,” Dobbs continued. “Someone using such a service to conduct unauthorized testing is illegal in many countries, however, the legal liability is that of the user, not of the service provider.”

Dobbs’s profile on GitHub includes more of his ideas about his work, including a curious piece on “software engineering ethics.” In his January 2020 treatise “My Software Engineering Journey,” Dobbs laments that nothing in his formal education prepared him for the reality that a great deal of his work would be so tedious and repetitive (this tracks closely with a 2020 piece here called Career Choice Tip: Cybercrime is Mostly Boring).

“One area of software engineering that I think should be covered more in university classes is maintenance,” Dobbs wrote. “Projects are often worked on for at most a few months, and students do not experience the maintenance aspect of software engineering until they reach the workplace. Let’s face it, ongoing maintenance of a project is boring; there is nothing like the euphoria of completing a project you have been working on for months and releasing it to the world, but I would say that half of my professional career has been related to maintenance.”

Allison Nixon is chief research officer at the New York-based cybersecurity firm Unit 221B. Nixon is part of a small group of researchers who have been closely tracking the DDoS-for-hire industry for years, and she said Dobbs’s claim that what he’s doing is legal makes sense given that it took years for the government to recognize the size of the problem.

“These guys are arguing that their services are legal because for a long time nothing happened to them,” Nixon said. “It’s difficult to argue something is illegal if no one has ever been arrested for it before.”

Nixon says the government’s fight against the booter services — and by extension other types of cybercrimes — is hampered by a legal system that often takes years to cycle through cybercrime cases.

“With cybercrime, the cycle between the crime and investigation and arrest can often take a year or more, and that’s for a really fast case,” Nixon said. “If someone robbed a store, we’d expect a police response within a few minutes. If someone robs a bank’s website, there might be some indication of police activity within a year.”

Nixon praised the 2022 and 2018 booter takedown operations as “huge steps forward,” but added that “there need to be more of them, and faster.”

“This time lag is part of the reason it’s so difficult to shut down the pipeline of new talent going into cybercrime,” she said. “They think what they’re doing is legal because nothing has happened, and because of the amount of time it takes to shut these things down. And it’s really a big problem, where we see a lot of people becoming criminals on the basis that what they’re doing isn’t really illegal because the cops won’t do anything.”

In December 2020, Dobbs filed an application with the state of Hawaii to withdraw IP Stresser Inc. from its roster of active companies. But according to prosecutors, Dobbs would continue to operate his DDoS-for-hire site until at least November 2022.

Two months after our 2020 email interview, Dobbs would earn his second bachelor’s degree (in computer science; his resume says he earned a bachelor’s in civil engineering from Drexel University in 2013). The federal charges against Dobbs came just as he was preparing to enter his final semester toward a master’s degree in computer science at the University of Hawaii.

Nixon says she has a message for anyone involved in operating a DDoS-for-hire service.

“Unless you are verifying that the target owns the infrastructure you’re targeting, there is no legal way to operate a DDoS-for-hire service,” she said. “There is no Terms of Service you could put on the site that would somehow make it legal.”

And her message to the customers of those booter services? It’s a compelling one to ponder, particularly now that investigators in the United States, U.K. and elsewhere have started going after booter service customers.

“When a booter service claims they don’t share logs, they’re lying because logs are legal leverage for when the booter service operator gets arrested,” Nixon said. “And when they do, you’re going to be the first people they throw under the bus.”