A recent surge in Clop ransomware attacks led researchers to spot a common thread in the first stage of the attack: the exploitation of a known and patched vulnerability in SolarWinds Serv-U file server software.
NCC Group's Cyber Incident Response Team recently spotted the attack chain while conducting incident response cases of Clop ransomware victims hit by the infamous T505 cybercrime group out of Russia.
"We believe exploiting such vulnerabilities is a recent initial access technique for TA505, deviating from the actor’s usual phishing-based approach," the researchers wrote in their findings.
The attackers exploited versions of the SolarWinds Serv-U software that have not been updated to the latest version that fixes the remote code execution flaw (CVE-2021-35211).
NCC Group recommends updating SolarWinds Serv-U software to the newest version; it outlined several indicators of compromise they spotted in the attacks.
Read the full report here.