Welcome to this week’s edition of the Threat Source newsletter.

I’ve been thinking a lot recently about the pros and cons of the way we publicize our threat research. I had a few conversations at Cisco Live with people — who are more generally IT-focused than hyper-focused on cybersecurity — about the amount of information we share on our blog and social media profiles. Our blog serves as the main mouthpiece for Talos, but I’m also always talking to our audience, directly or indirectly, through social media channels, our podcasts, or out in the world at conferences. But during these conversations, readers may wonder if we’re indirectly “helping” the bad guys by pointing out what they’re doing wrong or what we are doing to track them.

There will always be pros and cons to any type of disclosure of information at this level of cybersecurity. But it’s important to know that we don’t take this issue lightly. When we publicize a technique — whether it be in a blog post, conference talk or podcast — those attackers are actively using, it forces them to change tactics and take time to make tweaks and changes. Unfortunately, we alone do not have the power to bring an end to cybercrime. However, if we can increase the cost of doing business for a threat actor, it's a win for defenders and potential victims. As defenders, we must keep attackers out of their comfort zone and force them to innovate or perish. Without that information being out there publicly, these bad actors could keep using the same tactics indefinitely to infect other targets.

This is by no means an easy decision to make, it’s a fine line all cybersecurity defenders must continually walk. But as we’ve pointed out several times, cybersecurity is a team sport. Prior to publishing any blog post, we take several steps to make sure everyone is on the same page, including victim notifications and information sharing with our partners like the Cyber Threat Alliance. I think we should all play on the same team and provide our teammates with as much information as possible so they’re ready for game time. To continue the analogy, information sharing with the public allows under-resourced teams to take action to defend themselves without needing to further strain their budgets and people.

It does us no good to either keep this information to ourselves and try to go out on our own and single-handedly defeat these threat actors because that’s never going to work. And it also doesn’t make sense to be super competitive. We always seek to protect our customers first and foremost, and that includes responsible disclosure policies from our vulnerability management team to our threat researchers. Our intelligence pushes research and defenders forward, and we will always seek to arm them with as much information as possible.

The one big thing

U.S. federal agencies unveiled a great deal about the MedusaLocker ransomware group last week with a joint advisory on the attackers’ operations. The U.S. Cybersecurity Infrastructure Security Agency, FBI and others shared several IOCs related to the actor, warning that they’ve spotted a recent uptick in MedusaLocker’s operations. MedusaLocker gains access to victim devices through vulnerable Remote Desktop Protocol (RDP) configurations or with malicious phishing and spam emails. Once on the targeted system, the attackers encrypt a victim’s files and await ransom payment while propagating across the network.

Why do I care? 

Cisco Talos first observed MedusaLocker operating in 2019. Clearly, the group has only expanded its operations since then and is now part of the massive ransomware-as-a-service industry that features several major threat actors. This group made its name by targeting health care organizations during the COVID-19 pandemic, but CISA’s advisory states any industry could be a target. The advisory includes new information on potential mitigations for this malware family, along with known IOCs to block associated with the group. 

So now what? 

In addition to implementing the mitigations outlined in the advisory, Cisco Secure also has several options available to defend against this attack. There are multiple Snort rules that detect this ransomware’s activity along with several ClamAV signatures. As with all ransomware activity, it’s important to have physical backups on hand in the event of an attack so you can recover quickly. And you can always be prepared for the worst with a Cisco Talos Incident Response plan and/or playbook. 

Other news of note

The North Korean state-sponsored actor Lazarus Group is suspected to be behind a recent $100 million cryptocurrency theft. Members of the group allegedly exploited the Harmony Horizon Bridge software that allows users to trade virtual currency between the Harmony blockchain and other blockchains. Attackers obtained username and passwords of Harmony employees that they then used to break into the bridge and deploy several money laundering techniques to hide their actions. The tactics in this case are similar to another attack in April in which attackers stole $600 million from Ronin Bridge. (Bloomberg, Fortune)

Bad actors are creating fake job applications and attending virtual interviews with deepfake videos. A new warning from the FBI states the adversaries are trying to obtain contractor-level jobs at technology companies, likely to steal sensitive information or make money illegitimately. These fake applicants use stolen identities, fake videos and doctored voices during the application process, including adding in what seem like normal human coughing, sneezing and blinking. The FBI recommends that recruiters or hiring managers look out for telltale signs of deepfake videos like sounds that do not line up with the video on the screen or unnatural lip movements. (TechCrunch, Gawker)

Google is warning of a high-severity vulnerability in the Chrome web browser for Android that is actively being exploited in the wild. CVE-2022-2294 is a heap buffer overflow bug that, if exploited, could lead to denial-of-service attacks or arbitrary code execution. The company released a security update to patch the vulnerability this week. This update also includes fixes for another high-severity vulnerability (CVE-2022-2295) and an unspecified internal issue discovered. This is the fourth zero-day vulnerability to pop up in Chrome this year. (Dark Reading, Decipher)

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Most prevalent malware files from Talos telemetry over the past week

SHA 256: 9f1f11a708d393e0a4109ae189bc64f1f3e312653dcf317a2bd406f18ffcc507

MD5: 2915b3f8b703eb744fc54c81f4a9c67f

Typical Filename: VID001.exe

Claimed Product: N/A

Detection Name: Win.Worm.Coinminer::1201

SHA 256: e4973db44081591e9bff5117946defbef6041397e56164f485cf8ec57b1d8934  
MD5: 93fefc3e88ffb78abb36365fa5cf857c  Typical Filename: Wextract  
Claimed Product: Internet Explorer  
Detection Name: PUA.Win.Trojan.Generic::85.lp.ret.sbx.tg

SHA 256: 125e12c8045689bb2a5dcad6fa2644847156dec8b533ee8a3653b432f8fd5645

MD5: 2c8ea737a232fd03ab80db672d50a17a

Typical Filename: LwssPlayer.scr

Claimed Product: 梦想之巅幻灯播放器

Detection Name: Auto.125E12.241442.in02

SHA 256: 1a234656f81e870cdeb0e648a6b305a41452c405cca21124de26b54f79d55ad0

MD5: 10f1561457242973e0fed724eec92f8c

Typical Filename: ntuser.vbe

Claimed Product: N/A

Detection Name: Auto.1A234656F8.211848.in07.Talos

SHA 256: 91e994229a7c8fdd899ce9b961516179da4c41be0818b5f07f07e4f4b4ebf28e

MD5: a7742a6d7d8b39f1a8cdf7f0b50f12bb

Typical Filename: wrsanvs.exe

Claimed Product: N/A

Detection Name: W32.Auto:91e994229a.in03.Talos