A ransomware group called Dark Angels made headlines this past week when it was revealed the crime group recently received a record $75 million data ransom payment from a Fortune 50 company. Security experts say the Dark Angels have been around since 2021, but the group doesn’t get much press because they work alone and maintain a low profile, picking one target at a time and favoring mass data theft over disrupting the victim’s operations.

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Security firm Zscaler ThreatLabz this month ranked Dark Angels as the top ransomware threat for 2024, noting that in early 2024 a victim paid the ransomware group $75 million — higher than any previously recorded ransom payment. ThreatLabz found Dark Angels has conducted some of the largest ransomware attacks to date, and yet little is known about the group.

Brett Stone-Gross, senior director of threat intelligence at ThreatLabz, said Dark Angels operate using an entirely different playbook than most other ransomware groups. For starters, he said, Dark Angels does not employ the typical ransomware affiliate model, which relies on hackers-for-hire to install malicious software that locks up infected systems.

“They really don’t want to be in the headlines or cause business disruptions,” Stone-Gross said. “They’re about making money and attracting as little attention as possible.”

Most ransomware groups maintain flashy victim leak sites which threaten to publish the target’s stolen data unless a ransom demand is paid. But the Dark Angels didn’t even have a victim shaming site until April 2023. And the leak site isn’t particularly well branded; it’s called Dunghill Leak.

The Dark Angels victim shaming site, Dunghill Leak.

“Nothing about them is flashy,” Stone-Gross said. “For the longest time, they didn’t even want to cause a big headline, but they probably felt compelled to create that leaks site because they wanted to show they were serious and that they were going to post victim data and make it accessible.”

Dark Angels is thought to be a Russia-based cybercrime syndicate whose distinguishing characteristic is stealing truly staggering amounts of data from major companies across multiple sectors, including healthcare, finance, government and education. For large businesses, the group has exfiltrated between 10-100 terabytes of data, which can take days or weeks to transfer, ThreatLabz found.

Like most ransom gangs, Dark Angels will publish data stolen from victims who do not pay. Some of the more notable victims listed on Dunghill Leak include the global food distribution firm Sysco, which disclosed a ransomware attack in May 2023; and the travel booking giant Sabre, which was hit by the Dark Angels in September 2023.

Stone-Gross said Dark Angels is often reluctant to deploy ransomware malware because such attacks work by locking up the target’s IT infrastructure, which typically causes the victim’s business to grind to a halt for days, weeks or even months on end. And those types of breaches tend to make headlines quickly.

“They selectively choose whether they want to deploy ransomware or not,” he said. “If they deem they can encrypt some files that won’t cause major disruptions — but will give them a ton of data — that’s what they’ll do. But really, what separates them from the rest is the volume of data they’re stealing. It’s a whole order of magnitude greater with Dark Angels. Companies losing vast amounts of data will pay these high ransoms.”

So who paid the record $75 million ransom? Bleeping Computer posited on July 30 that the victim was the pharmaceutical giant Cencora (formerly AmeriSourceBergen Corporation), which reported a data security incident to the U.S. Securities and Exchange Commission (SEC) on February 21, 2024.

The SEC requires publicly-traded companies to disclose a potentially material cybersecurity event within four days of the incident. Cencora is currently #10 on the Fortune 500 list, generating more than $262 billion in revenue last year.

Cencora did not respond to questions about whether it had made a ransom payment in connection with the February cybersecurity incident, and referred KrebsOnSecurity to expenses listed under “Other” in the restructuring section of their latest quarterly financial report (PDF). That report states that the majority of the $30 million cost in “Other” was associated with the breach.

Cencora’s quarterly statement said the incident affected a standalone legacy information technology platform in one country and the foreign business unit’s ability to operate in that country for approximately two weeks.

Cencora’s 2024 1st quarter report documents a $30 million cost associated with a data exfiltration event in mid-February 2024.

In its most recent State of Ransomware report (PDF), security firm Sophos found the average ransomware payment had increased fivefold in the past year, from $400,000 in 2023 to $2 million. Sophos says that in more than four-fifths (82%) of cases funding for the ransom came from multiple sources. Overall, 40% of total ransom funding came from the organizations themselves and 23% from insurance providers.

Further reading: ThreatLabz ransomware report (PDF).

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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 a DirecTV/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.