Justice AV Solutions Viewer: vulnerability flaw under attack

What is affected

Justice AV Solutions Viewer is mostly run by companies, schools and public bodies, not on home computers. You are unlikely to have it yourself, but organisations that hold your data may. Breaches that start with flaws like this one are how personal data ends up leaked.

Justice AV Solutions (JAVS) Viewer installer contains a malicious version of ffmpeg.exe, named fffmpeg.exe (SHA256: 421a4ad2615941b177b6ec4ab5e239c14e62af2ab07c6df1741e2a62223223c4). When run, this creates a backdoor connection to a malicious C2 server.

What an attacker can do

This is a vulnerability flaw. It lets an attacker misuse the product in a way its maker did not intend. CISA lists it because attackers are confirmed to be using it against real systems.

How it is reached

Over the internet or network

Access the attacker needs

An administrator account

Does the victim have to do something?

Yes, the victim must take a specific action

What to do

1. At home: nothing to install. Keep your own devices updated and use a different password for every service, so that a breach at one organisation does not open your other accounts.
2. If you administer Justice AV Solutions Viewer at work: apply the vendor's fix or mitigation now and review logs for signs of compromise, because the flaw was being exploited before it was listed.
3. If the product is past its support date and no fix exists, take it off the internet or retire it.

Apply mitigations per vendor instructions or discontinue use of the product if mitigations are unavailable.

Vendor advisories and fixes

• rapid7.comwww.rapid7.com/blog/post/2024/05/23/cve-2024-4978-backdoored-justice-av-solutions-viewer-s
• javs.comwww.javs.com/downloads

How urgent is it

CISA added this vulnerability to its Known Exploited Vulnerabilities catalogue on May 29, 2024, which means there is reliable evidence of attacks in the wild. US federal agencies must fix it by June 19, 2024, a deadline that has already passed. That deadline does not bind anyone else, but it shows how seriously the agency rates it.

The EPSS model estimates a 27% probability that this flaw will be exploited somewhere in the next 30 days. That is higher than 98% of all scored vulnerabilities.

Its CVSS severity score is 8.7 out of 10 (high), as recorded in the US National Vulnerability Database.

Technical description

Justice AV Solutions Viewer Setup 8.3.7.250-1 contains a malicious binary when executed and is signed with an unexpected authenticode signature. A remote, privileged threat actor may exploit this vulnerability to execute of unauthorized PowerShell commands.