Thread Hijacking: Phishes That Prey on Your Curiosity

Thread hijacking attacks. They happen when someone you know has their email account compromised, and you are suddenly dropped into an existing conversation between the sender and someone else. These missives draw on the recipient’s natural curiosity about being copied on a private discussion, which is modified to include a malicious link or attachment. Here’s the story of a thread hijacking attack in which a journalist was copied on a phishing email from the unwilling subject of a recent scoop.

In Sept. 2023, the Pennsylvania news outlet LancasterOnline.com published a story about Adam Kidan, a wealthy businessman with a criminal past who is a major donor to Republican causes and candidates, including Rep. Lloyd Smucker (R-Pa).

Several months after that piece ran, the story’s author Brett Sholtis received two emails from Kidan, both of which contained attachments. One of the messages appeared to be a lengthy conversation between Kidan and a colleague, with the subject line, “Re: Successfully sent data.” The second missive was a more brief email from Kidan with the subject, “Acknowledge New Work Order,” and a message that read simply, “Please find the attached.”

Sholtis said he clicked the attachment in one of the messages, which then launched a web page that looked exactly like a Microsoft Office 365 login page. An analysis of the webpage reveals it would check any submitted credentials at the real Microsoft website, and return an error if the user entered bogus account information. A successful login would record the submitted credentials and forward the victim to the real Microsoft website.

But Sholtis said he didn’t enter his Outlook username and password. Instead, he forwarded the messages to LancasterOneline’s IT team, which quickly flagged them as phishing attempts.

LancasterOnline Executive Editor Tom Murse said the two phishing messages from Mr. Kidan raised eyebrows in the newsroom because Kidan had threatened to sue the news outlet multiple times over Sholtis’s story.

“We were just perplexed,” Murse said. “It seemed to be a phishing attempt but we were confused why it would come from a prominent businessman we’ve written about. Our initial response was confusion, but we didn’t know what else to do with it other than to send it to the FBI.”

In 2006, Kidan was sentenced to 70 months in federal prison after pleading guilty to defrauding lenders along with Jack Abramoff, the disgraced lobbyist whose corruption became a symbol of the excesses of Washington influence peddling. He was paroled in 2009, and in 2014 moved his family to a home in Lancaster County, Pa.

The FBI hasn’t responded to LancasterOnline’s tip. Messages sent by KrebsOnSecurity to Kidan’s emails addresses were returned as blocked. Messages left with Mr. Kidan’s company, Empire Workforce Solutions, went unreturned.

No doubt the FBI saw the messages from Kidan for what they likely were: The result of Mr. Kidan having his Microsoft Outlook account compromised and used to send malicious email to people in his contacts list.

Thread hijacking attacks are hardly new, but that is mainly true because many Internet users still don’t know how to identify them. The email security firm Proofpoint says it has tracked north of 90 million malicious messages in the last five years that leverage this attack method.

One key reason thread hijacking is so successful is that these attacks generally do not include the tell that exposes most phishing scams: A fabricated sense of urgency. A majority of phishing threats warn of negative consequences should you fail to act quickly — such as an account suspension or an unauthorized high-dollar charge going through.

In contrast, thread hijacking campaigns tend to patiently prey on the natural curiosity of the recipient.

Ryan Kalember, chief strategy officer at Proofpoint, said probably the most ubiquitous examples of thread hijacking are “CEO fraud” or “business email compromise” scams, wherein employees are tricked by an email from a senior executive into wiring millions of dollars to fraudsters overseas.

But Kalember said these low-tech attacks can nevertheless be quite effective because they tend to catch people off-guard.

“It works because you feel like you’re suddenly included in an important conversation,” Kalember said. “It just registers a lot differently when people start reading, because you think you’re observing a private conversation between two different people.”

Some thread hijacking attacks actually involve multiple threat actors who are actively conversing while copying — but not addressing — the recipient.

“We call these multi-persona phishing scams, and they’re often paired with thread hijacking,” Kalember said. “It’s basically a way to build a little more affinity than just copying people on an email. And the longer the conversation goes on, the higher their success rate seems to be because some people start replying to the thread [and participating] psycho-socially.”

The best advice to sidestep phishing scams is to avoid clicking on links or attachments that arrive unbidden in emails, text messages and other mediums. If you’re unsure whether the message is legitimate, take a deep breath and visit the site or service in question manually — ideally, using a browser bookmark so as to avoid potential typosquatting sites.

Why is .US Being Used to Phish So Many of Us?

Domain names ending in “.US” — the top-level domain for the United States — are among the most prevalent in phishing scams, new research shows. This is noteworthy because .US is overseen by the U.S. government, which is frequently the target of phishing domains ending in .US. Also, .US domains are only supposed to be available to U.S. citizens and to those who can demonstrate that they have a physical presence in the United States.

.US is the “country code top-level domain” or ccTLD of the United States. Most countries have their own ccTLDs: .MX for Mexico, for example, or .CA for Canada. But few other major countries in the world have anywhere near as many phishing domains each year as .US.

That’s according to The Interisle Consulting Group, which gathers phishing data from multiple industry sources and publishes an annual report on the latest trends. Interisle’s newest study examined six million phishing reports between May 1, 2022 and April 30, 2023, and found 30,000 .US phishing domains.

.US is overseen by the National Telecommunications and Information Administration (NTIA), an executive branch agency of the U.S. Department of Commerce. However, NTIA currently contracts out the management of the .US domain to GoDaddy, by far the world’s largest domain registrar.

Under NTIA regulations, the administrator of the .US registry must take certain steps to verify that their customers actually reside in the United States, or own organizations based in the U.S. But Interisle found that whatever GoDaddy was doing to manage that vetting process wasn’t working.

“The .US ‘nexus’ requirement theoretically limits registrations to parties with a national connection, but .US had very high numbers of phishing domains,” Interisle wrote. “This indicates a possible problem with the administration or application of the nexus requirements.”

Dean Marks is emeritus executive director for a group called the Coalition for Online Accountability, which has been critical of the NTIA’s stewardship of .US. Marks says virtually all European Union member state ccTLDs that enforce nexus restrictions also have massively lower levels of abuse due to their policies and oversight.

“Even very large ccTLDs, like .de for Germany — which has a far larger market share of domain name registrations than .US — have very low levels of abuse, including phishing and malware,” Marks told KrebsOnSecurity. “In my view, this situation with .US should not be acceptable to the U.S. government overall, nor to the US public.”

Marks said there are very few phishing domains ever registered in other ccTLDs that also restrict registrations to their citizens, such as .HU (Hungary), .NZ (New Zealand), and .FI (Finland), where a connection to the country, a proof of identity, or evidence of incorporation are required.

“Or .LK (Sri Lanka), where the acceptable use policy includes a ‘lock and suspend’ if domains are reported for suspicious activity,” Marks said. “These ccTLDs make a strong case for validating domain registrants in the interest of public safety.”

Sadly, .US has been a cesspool of phishing activity for many years. As far back as 2018, Interisle found .US domains were the worst in the world for spam, botnet (attack infrastructure for DDOS etc.) and illicit or harmful content. Back then, .US was being operated by a different contractor.

In response to questions from KrebsOnSecurity, GoDaddy said all .US registrants must certify that they meet the NTIA’s nexus requirements. But this appears to be little more than an affirmative response that is already pre-selected for all new registrants.

Attempting to register a .US domain through GoDaddy, for example, leads to a U.S. Registration Information page that auto-populates the nexus attestation field with the response, “I am a citizen of the US.” Other options include, “I am a permanent resident of the US,” and “My primary domicile is in the US.” It currently costs just $4.99 to obtain a .US domain through GoDaddy.

GoDaddy said it also conducts a scan of selected registration request information, and conducts “spot checks” on registrant information.

“We conduct regular reviews, per policy, of registration data within the Registry database to determine Nexus compliance with ongoing communications to registrars and registrants,” the company said in a written statement.

GoDaddy says it “is committed to supporting a safer online environment and proactively addressing this issue by assessing it against our own anti-abuse mitigation system.”

“We stand against DNS abuse in any form and maintain multiple systems and protocols to protect all the TLDs we operate,” the statement continued. “We will continue to work with registrars, cybersecurity firms and other stakeholders to make progress with this complex challenge.”

Interisle found significant numbers of .US domains were registered to attack some of the United States’ most prominent companies, including Bank of America, Amazon, Apple, AT&T, Citi, Comcast, Microsoft, Meta, and Target.

“Ironically, at least 109 of the .US domains in our data were used to attack the United States government, specifically the United States Postal Service and its customers,” Interisle wrote. “.US domains were also used to attack foreign government operations: six .US domains were used to attack Australian government services, six attacked Great’s Britain’s Royal Mail, one attacked Canada Post, and one attacked the Denmark Tax Authority.”

The NTIA recently published a proposal that would allow GoDaddy to redact registrant data from WHOIS registration records. The current charter for .US specifies that all .US registration records be public.

Interisle argues that without more stringent efforts to verify a United States nexus for new .US domain registrants, the NTIA’s proposal will make it even more difficult to identify phishers and verify registrants’ identities and nexus qualifications.

In a written statement, the NTIA said DNS abuse is a priority issue for the agency, and that NTIA supports “evidence-based policymaking.”

“We look forward to reviewing the report and will engage with our contractor for the .US domain on steps that we can take not only to address phishing, but the other forms of DNS abuse as well,” the statement reads.

Interisle sources its phishing data from several places, including the Anti-Phishing Working Group (APWG), OpenPhish, PhishTank, and Spamhaus. For more phishing facts, see Interisle’s 2023 Phishing Landscape report (PDF).’

Update, Sept. 5, 1:44 p.m. ET: Updated story with statement provided today by the NTIA.

Breach Exposes Users of Microleaves Proxy Service

Microleaves, a ten-year-old proxy service that lets customers route their web traffic through millions of Microsoft Windows computers, recently fixed a vulnerability in their website that exposed their entire user database. Microleaves claims its proxy software is installed with user consent, but data exposed in the breach shows the service has a lengthy history of being supplied with new proxies by affiliates incentivized to distribute the software any which way they can — such as by secretly bundling it with other titles.

Launched in 2013, Microleaves is a service that allows customers to route their Internet traffic through PCs in virtually any country or city around the globe. Microleaves works by changing each customer’s Internet Protocol (IP) address every five to ten minutes.

The service, which accepts PayPal, Bitcoin and all major credit cards, is aimed primarily at enterprises engaged in repetitive, automated activity that often results in an IP address being temporarily blocked — such as data scraping, or mass-creating new accounts at some service online.

In response to a report about the data exposure from KrebsOnSecurity, Microleaves said it was grateful for being notified about a “very serious issue regarding our customer information.”

Abhishek Gupta is the PR and marketing manager for Microleaves, which he said in the process of being rebranded to “Shifter.io.” Gupta said the report qualified as a “medium” severity security issue in Shifter’s brand new bug bounty program (the site makes no mention of a bug bounty), which he said offers up to $2,000 for reporting data exposure issues like the one they just fixed. KrebsOnSecurity declined the offer and requested that Shifter donate the amount to the Electronic Frontier Foundation (EFF), a digital rights group.

From its inception nearly a decade ago, Microleaves has claimed to lease between 20-30 million IPs via its service at any time. Riley Kilmer, co-founder of the proxy-tracking service Spur.us, said that 20-30 million number might be accurate for Shifter if measured across a six-month time frame. Currently, Spur is tracking roughly a quarter-million proxies associated with Microleaves/Shifter each day, with a high rate of churn in IPs.

Early on, this rather large volume of IP addresses led many to speculate that Microleaves was just a botnet which was being resold as a commercial proxy service.

The very first discussion thread started by the new user Microleaves on the forum BlackHatWorld in 2013 sought forum members who could help test and grow the proxy network. At the time, the Microleaves user said their proxy network had 150,000 IPs globally, and was growing quickly.

One of BlackHatWorld’s moderators asked the administrator of the forum to review the Microleaves post.

“User states has 150k proxies,” the forum skeptic wrote. “No seller on BHW has 150k working daily proxies none of us do. Which hints at a possible BOTNET. That’s the only way you will get 150k.”

Microleaves has long been classified by antivirus companies as adware or as a “potentially unwanted program” (PUP), the euphemism that antivirus companies use to describe executable files that get installed with ambiguous consent at best, and are often part of a bundle of software tied to some “free” download. Security vendor Kaspersky flags the Microleaves family of software as a trojan horse program that commandeers the user’s Internet connection as a proxy without notifying the user.

“While working, these Trojans pose as Microsoft Windows Update,” Kaspersky wrote.

In a February 2014 post to BlackHatWorld, Microleaves announced that its sister service — reverseproxies[.]com — was now offering an “Auto CAPTCHA Solving Service,” which automates the solving of those squiggly and sometimes frustrating puzzles that many websites use to distinguish bots from real visitors. The CAPTCHA service was offered as an add-on to the Microleaves proxy service, and ranged in price from $20 for a 2-day trial to $320 for solving up to 80 captchas simultaneously.

“We break normal Recaptcha with 60-90% success rate, recaptcha with blobs 30% success, and 500+ other captcha,” Microleaves wrote. “As you know all success rate on recaptcha depends very much on good proxies that are fresh and not spammed!”

WHO IS ACIDUT?

The exposed Microleaves user database shows that the first user created on the service — username “admin” — used the email address alex.iulian@aol.com. A search on that email address in Constella Intelligence, a service that tracks breached data, reveals it was used to create an account at the link shortening service bit.ly under the name Alexandru Florea, and the username “Acidut.” [Full disclosure: Constella is currently an advertiser on this website].

According to the cyber intelligence company Intel 471, a user named Acidut with the email address iulyan87_4u@gmail.com had an active presence on almost a dozen shadowy money-making and cybercrime forums from 2010 to 2017, including BlackHatWorld, Carder[.]pro, Hackforums, OpenSC, and CPAElites.

In a 2011 post on Hackforums, Acidut said they were building a botnet using an “exploit kit,” a set of browser exploits made to be stitched into hacked websites and foist malware on visitors. Acidut claimed their exploit kit was generating 3,000 to 5,000 new bots each day. OpenSC was hacked at one point, and its private messages show Acidut purchased a license from Exmanoize, the handle used by the creator of the Eleonore Exploit Kit.

By November 2013, Acidut was advertising the sale of “26 million SOCKS residential proxies.” In a March 2016 post to CPAElites, Acidut said they had a worthwhile offer for people involved in pay-per-install or “PPI” schemes, which match criminal gangs who pay for malware installs with enterprising hackers looking to sell access to compromised PCs and websites.

Because pay-per-install affiliate schemes rarely impose restrictions on how the software can be installed, such programs can be appealing for cybercriminals who already control large collections of hacked machines and/or compromised websites. Indeed, Acidut went a step further, adding that their program could be quietly and invisibly nested inside of other programs.

“For those of you who are doing PPI I have a global offer that you can bundle to your installer,” Acidut wrote. “I am looking for many installs for an app that will generate website visits. The installer has a silence version which you can use inside your installer. I am looking to buy as many daily installs as possible worldwide, except China.”

Asked about the source of their proxies in 2014, the Microleaves user responded that it was “something related to a PPI network. I can’t say more and I won’t get into details.”

Acidut authored a similar message on the forum BlackHatWorld in 2013, where they encouraged users to contact them on Skype at the username “nevo.julian.” That same Skype contact address was listed prominently on the Microleaves homepage up until about a week ago when KrebsOnSecurity first reached out to the company.

ONLINE[.]IO (NOW MERCIFULLY OFFLINE)

There is a Facebook profile for an Alexandru Iulian Florea from Constanta, Romania, whose username on the social media network is Acidut. Prior to KrebsOnSecurity alerting Shifter of its data breach, the Acidut profile page associated Florea with the websites microleaves.com, shrooms.io, leftclick[.]io, and online[.]io. Mr. Florea did not respond to multiple requests for comment, and his Facebook page no longer mentions these domains.

Leftclick and online[.]io emerged as subsidiaries of Microleaves between 2017 and 2018. According to a help wanted ad posted in 2018 for a developer position at online[.]io, the company’s services were brazenly pitched to investors as “a cybersecurity and privacy tool kit, offering extensive protection using advanced adblocking, anti-tracking systems, malware protection, and revolutionary VPN access based on residential IPs.”

“Online[.]io is developing the first fully decentralized peer-to-peer networking technology and revolutionizing the browsing experience by making it faster, ad free, more reliable, secure and non-trackable, thus freeing the Internet from annoying ads, malware, and trackers,” reads the rest of that help wanted ad.

Microleaves CEO Alexandru Florea gave an “interview” to the website Irishtechnews.ie in 2018, in which he explained how Online[.]io (OIO) was going to upend the online advertising and security industries with its initial coin offering (ICO). The word interview is in air quotes because the following statements by Florea deserved some serious pushback by the interviewer.

“Online[.]io solution, developed using the Ethereum blockchain, aims at disrupting the digital advertising market valued at more than $1 trillion USD,” Alexandru enthused. “By staking OIO tokens and implementing our solution, the website operators will be able to access a new non-invasive revenue stream, which capitalizes on time spent by users online.”

“At the same time, internet users who stake OIO tokens will have the opportunity to monetize on the time spent online by themselves and their peers on the World Wide Web,” he continued. “The time spent by users online will lead to ICE tokens being mined, which in turn can be used in the dedicated merchant system or traded on exchanges and consequently changed to fiat.”

Translation: If you install our proxy bot/CAPTCHA-solver/ad software on your computer — or as an exploit kit on your website — we’ll make millions hijacking ads and you will be rewarded with heaps of soon-to-be-worthless shitcoin. Oh, and all your security woes will disappear, too.

It’s unclear how many Internet users and websites willingly agreed to get bombarded with Online[.]io’s annoying ads and search hijackers — and to have their PC turned into a proxy or CAPTCHA-solving zombie for others. But that is exactly what multiple security companies said happened when users encountered online[.]io, which operated using the Microsoft Windows process name of “online-guardian.exe.”

Incredibly, Crunchbase says Online[.]io raised $6 million in funding for an initial coin offering in 2018, based on the plainly ludicrous claims made above. Since then, however, online[.]io seems to have gone…offline, for good.

SUPER TECH VENTURES?

Until this week, Shifter.io’s website also exposed information about its customer base and most active users, as well as how much money each client has paid over the lifetime of their subscription. The data indicates Shifter has earned more than $11.7 million in direct payments, although it’s unclear how far back in time those payment records go, or how complete they are.

The bulk of Shifter customers who spent more than $100,000 at the proxy service appear to be digital advertising companies, including some located in the United States. None of the several Shifter customers approached by KrebsOnSecurity agreed to be interviewed.

Shifter’s Gupta said he’d been with the company for three years, since the new owner took over the company and made the rebrand to Shifter.

“The company has been on the market for a long time, but operated under a different brand called Microleaves, until new ownership and management took over the company started a reorganization process that is still on-going,” Gupta said. “We are fully transparent. Mostly [our customers] work in the data scraping niche, this is why we actually developed more products in this zone and made a big shift towards APIs and integrated solutions in the past year.”

Ah yes, the same APIs and integrated solutions that were found exposed to the Internet and leaking all of Shifter’s customer information.

Gupta said the original founder of Microleaves was a man from India, who later sold the business to Florea. According to Gupta, the Romanian entrepreneur had multiple issues in trying to run the company, and then sold it three years ago to the current owner — Super Tech Ventures, a private equity company based in Taiwan.

“Our CEO is Wang Wei, he has been with the company since 3 years ago,” Gupta said. “Mr. Florea left the company two years ago after ending this transition period.”

Google and other search engines seem to know nothing about a Super Tech Ventures based in Taiwan. Incredibly, Shifter’s own PR person claimed that he, too, was in the dark on this subject.

“I would love to help, but I really don’t know much about the mother company,” Gupta said, essentially walking back his “fully transparent” statement. “I know they are a branch of the bigger group of asian investment firms focused on private equity in multiple industries.”

Adware and proxy software are often bundled together with “free” software utilities online, or with popular software titles that have been pirated and quietly fused with installers tied to various PPI affiliate schemes.

But just as often, these intrusive programs will include some type of notice — even if installed as part of a software bundle — that many users simply do not read and click “Next” to get on with installing whatever software they’re seeking to use. In these cases, selecting the “basic” or “default” settings while installing usually hides any per-program installation prompts, and assumes you agree to all of the bundled programs being installed. It’s always best to opt for the “custom” installation mode, which can give you a better idea of what is actually being installed, and can let you control certain aspects of the installation.

Either way, it’s best to start with the assumption that if a software or service online is “free,” that there is likely some component involved that allows the provider of that service to monetize your activity. As KrebsOnSecurity noted at the conclusion of last week’s story on a China-based proxy service called 911, the rule of thumb for transacting online is that if you’re not the paying customer, then you and/or your devices are probably the product that’s being sold to others.

Further reading on proxy services:

July 18, 2022: A Deep Dive Into the Residential Proxy Service ‘911’
June 28, 2022: The Link Between AWM Proxy & the Glupteba Botnet
June 22, 2022: Meet the Administrators of the RSOCKS Proxy Botnet
Sept. 1, 2021: 15-Year-Old Malware Proxy Network VIP72 Goes Dark
Aug. 19, 2019: The Rise of “Bulletproof” Residential Networks