BlackCat Ransomware Raises Ante After FBI Disruption

The U.S. Federal Bureau of Investigation (FBI) disclosed today that it infiltrated the world’s second most prolific ransomware gang, a Russia-based criminal group known as ALPHV and BlackCat. The FBI said it seized the gang’s darknet website, and released a decryption tool that hundreds of victim companies can use to recover systems. Meanwhile, BlackCat responded by briefly “unseizing” its darknet site with a message promising 90 percent commissions for affiliates who continue to work with the crime group, and open season on everything from hospitals to nuclear power plants.

Whispers of a possible law enforcement action against BlackCat came in the first week of December, after the ransomware group’s darknet site went offline and remained unavailable for roughly five days. BlackCat eventually managed to bring its site back online, blaming the outage on equipment malfunctions.

But earlier today, the BlackCat website was replaced with an FBI seizure notice, while federal prosecutors in Florida released a search warrant explaining how FBI agents were able to gain access to and disrupt the group’s operations.

A statement on the operation from the U.S. Department of Justice says the FBI developed a decryption tool that allowed agency field offices and partners globally to offer more than 500 affected victims the ability to restore their systems.

“With a decryption tool provided by the FBI to hundreds of ransomware victims worldwide, businesses and schools were able to reopen, and health care and emergency services were able to come back online,” Deputy Attorney General Lisa O. Monaco said. “We will continue to prioritize disruptions and place victims at the center of our strategy to dismantle the ecosystem fueling cybercrime.”

The DOJ reports that since BlackCat’s formation roughly 18 months ago, the crime group has targeted the computer networks of more than 1,000 victim organizations. BlackCat attacks usually involve encryption and theft of data; if victims refuse to pay a ransom, the attackers typically publish the stolen data on a BlackCat-linked darknet site.

BlackCat formed by recruiting operators from several competing or disbanded ransomware organizations — including REvil, BlackMatter and DarkSide. The latter group was responsible for the Colonial Pipeline attack in May 2021 that caused nationwide fuel shortages and price spikes.

Like many other ransomware operations, BlackCat operates under the “ransomware-as-a-service” model, where teams of developers maintain and update the ransomware code, as well as all of its supporting infrastructure. Affiliates are incentivized to attack high-value targets because they generally reap 60-80 percent of any payouts, with the remainder going to the crooks running the ransomware operation.

BlackCat was able to briefly regain control over their darknet server today. Not long after the FBI’s seizure notice went live the homepage was “unseized” and retrofitted with a statement about the incident from the ransomware group’s perspective.

BlackCat claimed that the FBI’s operation only touched a portion of its operations, and that as a result of the FBI’s actions an additional 3,000 victims will no longer have the option of receiving decryption keys. The group also said it was formally removing any restrictions or discouragement against targeting hospitals or other critical infrastructure.

“Because of their actions, we are introducing new rules, or rather, we are removing ALL rules except one, you cannot touch the CIS [a common restriction against attacking organizations in Russia or the Commonwealth of Independent States]. You can now block hospitals, nuclear power plants, anything, anywhere.”

The crime group also said it was setting affiliate commissions at 90 percent, presumably to attract interest from potential affiliates who might otherwise be spooked by the FBI’s recent infiltration. BlackCat also promised that all “advertisers” under this new scheme would manage their affiliate accounts from data centers that are completely isolated from each other.

BlackCat’s darknet site currently displays the FBI seizure notice. But as BleepingComputer founder Lawrence Abrams explained on Mastodon, both the FBI and BlackCat have the private keys associated with the Tor hidden service URL for BlackCat’s victim shaming and data leak site.

“Whoever is the latest to publish the hidden service on Tor (in this case the BlackCat data leak site), will resume control over the URL,” Abrams said. “Expect to see this type of back and forth over the next couple of days.”

The DOJ says anyone with information about BlackCat affiliates or their activities may be eligible for up to a $10 million reward through the State Department’s “Rewards for Justice” program, which accepts submissions through a Tor-based tip line (visiting the site is only possible using the Tor browser).

Further reading: CISA StopRansomware Alert on the tools, techniques and procedures used by ALPHV/BlackCat.

It Might Be Our Data, But It’s Not Our Breach

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.

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.

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.

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.”