Ransomware groups are constantly devising new methods for infecting victims and convincing them to pay up, but a couple of strategies tested recently seem especially devious. The first centers on targeting healthcare organizations that offer consultations over the Internet and sending them booby-trapped medical records for the “patient.” The other involves carefully editing email inboxes of public company executives to make it appear that some were involved in insider trading.

Alex Holden is founder of Hold Security, a Milwaukee-based cybersecurity firm. Holden’s team gained visibility into discussions among members of two different ransom groups: CLOP (a.k.a. “Cl0p” a.k.a. “TA505“), and a newer ransom group known as Venus.

Last month, the U.S. Department of Health and Human Services (HHS) warned that Venus ransomware attacks were targeting a number of U.S. healthcare organizations. First spotted in mid-August 2022, Venus is known for hacking into victims’ publicly-exposed Remote Desktop services to encrypt Windows devices.

Holden said the internal discussions among the Venus group members indicate this gang has no problem gaining access to victim organizations.

“The Venus group has problems getting paid,” Holden said. “They are targeting a lot of U.S. companies, but nobody wants to pay them.”

Which might explain why their latest scheme centers on trying to frame executives at public companies for insider trading charges. Venus indicated it recently had success with a method that involves carefully editing one or more email inbox files at a victim firm — to insert messages discussing plans to trade large volumes of the company’s stock based on non-public information.

“We imitate correspondence of the [CEO] with a certain insider who shares financial reports of his companies through which your victim allegedly trades in the stock market, which naturally is a criminal offense and — according to US federal laws [includes the possibility of up to] 20 years in prison,” one CLOP member wrote to an underling.

“You need to create this file and inject into the machine(s) like this so that metadata would say that they were created on his computer,” they continued. “One of my clients did it, I don’t know how. In addition to pst, you need to decompose several files into different places, so that metadata says the files are native from a certain date and time rather than created yesterday on an unknown machine.”

Holden said it’s not easy to plant emails into an inbox, but it can be done with Microsoft Outlook .pst files, which the attackers may also have access to if they’d already compromised a victim network.

“It’s not going to be forensically solid, but that’s not what they care about,” he said. “It still has the potential to be a huge scandal — at least for a while — when a victim is being threatened with the publication or release of these records.”

The Venus ransom group’s extortion note. Image: Tripwire.com

Holden said the CLOP ransomware gang has a different problem of late: Not enough victims. The intercepted CLOP communication seen by KrebsOnSecurity shows the group bragged about twice having success infiltrating new victims in the healthcare industry by sending them infected files disguised as ultrasound images or other medical documents for a patient seeking a remote consultation.

The CLOP members said one tried-and-true method of infecting healthcare providers involved gathering healthcare insurance and payment data to use in submitting requests for a remote consultation on a patient who has cirrhosis of the liver.

“Basically, they’re counting on doctors or nurses reviewing the patient’s chart and scans just before the appointment,” Holden said. “They initially discussed going in with cardiovascular issues, but decided cirrhosis or fibrosis of the liver would be more likely to be diagnosable remotely from existing test results and scans.”

While CLOP as a money making collective is a fairly young organization, security experts say CLOP members hail from a group of Threat Actors (TA) known as “TA505,” which MITRE’s ATT&CK database says is a financially motivated cybercrime group that has been active since at least 2014. “This group is known for frequently changing malware and driving global trends in criminal malware distribution,” MITRE assessed.

In April, 2021, KrebsOnSecurity detailed how CLOP helped pioneer another innovation aimed at pushing more victims into paying an extortion demand: Emailing the ransomware victim’s customers and partners directly and warning that their data would be leaked to the dark web unless they can convince the victim firm to pay up.

Security firm Tripwire points out that the HHS advisory on Venus says multiple threat actor groups are likely distributing the Venus ransomware. Tripwire’s tips for all organizations on avoiding ransomware attacks include:

• Making secure offsite backups.
• Running up-to-date security solutions and ensuring that your computers are protected with the latest security patches against vulnerabilities.
• Using hard-to-crack unique passwords to protect sensitive data and accounts, as well as enabling multi-factor authentication.
• Encrypting sensitive data wherever possible.
• Continuously educating and informing staff about the risks and methods used by cybercriminals to launch attacks and steal data.

While the above tips are important and useful, one critical area of ransomware preparedness overlooked by too many organizations is the need to develop — and then periodically rehearse — a plan for how everyone in the organization should respond in the event of a ransomware or data ransom incident. Drilling this breach response plan is key because it helps expose weaknesses in those plans that could be exploited by the intruders.

As noted in last year’s story Don’t Wanna Pay Ransom Gangs? Test Your Backups, experts say the biggest reason ransomware targets and/or their insurance providers still pay when they already have reliable backups of their systems and data is that nobody at the victim organization bothered to test in advance how long this data restoration process might take.

“Suddenly the victim notices they have a couple of petabytes of data to restore over the Internet, and they realize that even with their fast connections it’s going to take three months to download all these backup files,” said Fabian Wosar, chief technology officer at Emsisoft. “A lot of IT teams never actually make even a back-of-the-napkin calculation of how long it would take them to restore from a data rate perspective.”

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In December 2021, Google filed a civil lawsuit against two Russian men thought to be responsible for operating Glupteba, one of the Internet’s largest and oldest botnets. The defendants, who initially pursued a strategy of counter suing Google for tortious interference in their sprawling cybercrime business, later brazenly offered to dismantle the botnet in exchange for payment from Google. The judge in the case was not amused, found for the plaintiff, and ordered the defendants and their U.S. attorney to pay Google’s legal fees.

A slide from a talk given in Sept. 2022 by Google researcher Luca Nagy. https://www.youtube.com/watch?v=5Gz6_I-wl0E&t=6s

Glupteba is a rootkit that steals passwords and other access credentials, disables security software, and tries to compromise other devices on the victim network — such as Internet routers and media storage servers — for use in relaying spam or other malicious traffic.

Collectively, the tens of thousands of systems infected with Glupteba on any given day feed into a number of major cybercriminal businesses: The botnet’s proprietors sell the credential data they steal, use the botnet to place disruptive ads on the infected computers, and mine cryptocurrencies. Glupteba also rents out infected systems as “proxies,” directing third-party traffic through the infected devices to disguise the origin of the traffic.

In June 2022, KrebsOnSecurity showed how the malware proxy services RSOCKS and AWMProxy were entirely dependent on the Glupteba botnet for fresh proxies, and that the founder of AWMProxy was Dmitry Starovikov — one of the Russian men named in Google’s lawsuit.

Google sued Starovikov and 15 other “John Doe” defendants, alleging violations of the Racketeer Influenced and Corrupt Organizations Act (RICO), the Computer Fraud and Abuse Act, trademark and unfair competition law, and unjust enrichment.

In June, Google and the named defendants agreed that the case would proceed as a nonjury action because Google had withdrawn its claim for damages — seeking only injunctive relief to halt the operations of the botnet.

The defendants, who worked for a Russian firm called “Valtron” that was also named in the lawsuit, told Google that they were interested in settling. The defendants said they could potentially help Google by taking the botnet offline.

Another slide from Google researcher Luca Nagy’s September 2022 talk on Glupteba.

But the court expressed frustration that the defendants were unwilling to consent to a permanent injunction, and at the same time were unable to articulate why an injunction forbidding them from engaging in unlawful activities would pose a problem.

“The Defendants insisted that they were not engaged in criminal activity, and that any alleged activity in which they were engaged was legitimate,” U.S. District Court Judge Denise Cote wrote. “Nevertheless, the Defendants resisted entry of a permanent injunction, asserting that Google’s use of the preliminary injunction had disrupted their normal business operations.”

While the defendants represented that they had the ability to dismantle the Glupteba botnet, when it came time for discovery — the stage in a lawsuit where both parties can compel the production of documents and other information pertinent to their case — the attorney for the defendants told the court his clients had been fired by Valtron in late 2021, and thus no longer had access to their work laptops or the botnet.

The lawyer for the defendants — New York-based cybercrime defense attorney Igor Litvak — told the court he first learned about his clients’ termination from Valtron on May 20, a fact Judge Cote said she found “troubling” given statements he made to the court after that date representing that his clients still had access to the botnet.

The court ultimately suspended the discovery process against Google, saying there was reason to believe the defendants sought discovery only “to learn whether they could circumvent the steps Google has taken to block the malware.”

On September 6, Litvak emailed Google that his clients were willing to discuss settlement.

“The parties held a call on September 8, at which Litvak explained that the Defendants would be willing to provide Google with the private keys for Bitcoin addresses associated with the Glupteba botnet, and that they would promise not to engage in their alleged criminal activity in the future (without any admission of wrongdoing),” the judge wrote.

“In exchange, the Defendants would receive Google’s agreement not to report them to law enforcement, and a payment of $1 million per defendant, plus $110,000 in attorney’s fees,” Judge Cote continued. “The Defendants stated that, although they do not currently have access to the private keys, Valtron would be willing to provide them with the private keys if the case were settled. The Defendants also stated that they believe these keys would help Google shut down the Glupteba botnet.”

Google rejected the defendants’ offer as extortionate, and reported it to law enforcement. Judge Cote also found Litvak was complicit in the defendants’ efforts to mislead the court, and ordered him to join his clients in paying Google’s legal fees.

“It is now clear that the Defendants appeared in this Court not to proceed in good faith to defend against Google’s claims but with the intent to abuse the court system and discovery rules to reap a profit from Google,” Judge Cote wrote.

Litvak has filed a motion to reconsider (PDF), asking the court to vacate the sanctions against him. He said his goal is to get the case back into court.

“The judge was completely wrong to issue sanctions,” Litvak said in an interview with KrebsOnSecurity. “From the beginning of the case, she acted as if she needed to protect Google from something. If the court does not decide to vacate the sanctions, we will have to go to the Second Circuit (Court of Appeals) and get justice there.”

In a statement on the court’s decision, Google said it will have significant ramifications for online crime, and that since its technical and legal attacks on the botnet last year, Google has observed a 78 percent reduction in the number of hosts infected by Glupteba.

“While Glupteba operators have resumed activity on some non-Google platforms and IoT devices, shining a legal spotlight on the group makes it less appealing for other criminal operations to work with them,” reads a blog post from Google’s General Counsel Halimah DeLaine Prado and vice president of engineering Royal Hansen. “And the steps [Google] took last year to disrupt their operations have already had significant impact.”

A report from the Polish computer emergency response team (CERT Orange Polksa) found Glupteba was the biggest malware threat in 2021.

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