On July 2, 2021, IT management software provider Kaseya suffered a ransomware attack that impacted its managed service provider (MSP) customers. Ransomware was pushed out to users of the Kaseya Virtual System Administrator (VSA) platform through the software update mechanism and, through them, to MSP clients. Kaspersky Lab said it found evidence of around 5,000 attempts to infect systems with ransomware across 22 countries in the first 3 days since the attack was identified. Kaseya recently said it believes around 1,500 of its direct customers and downstream businesses were affected.
The attackers exploited vulnerabilities in the KSA platform that had been reported to Kaseya by the Dutch Institute for Vulnerability Disclosure (DIVD) in April. Kaseya had issued updates to fix four of the seven reported vulnerabilities in April and May and was working on patches to fix the remaining three flaws. One of those flaws, CVE-2021-30116, was a credential leaking flaw which was exploited by the REvil ransomware gang before the patch was released.
Kaseya detected the attack quickly and was able to implement mitigations that limited the extent of the attacks. the steps taken by Kaseya have been effective at blocking any further attacks, customers are now at risk from Kaseya phishing campaigns.
Cybercriminals have started conducting phishing campaigns targeting Kaseya customers pushing Cobalt Strike payloads disguised as Kaseya VSA security updates. Cobalt Strike is a legitimate penetration testing and threat emulation tool, but it is also extensively used by hackers and ransomware gangs to gain remote access to business networks.
The campaign was first detected by the Threat intelligence team at Malwarebytes. The emails contain an attachment named SecurityUpdates.exe and a hyperlink that claims to provide a Microsoft update to fix the Kaseya vulnerability exploited by the ransomware gang.
Users are told to open the attached file or click the link in the email to update the Kaseya VSA to protect against ransomware attacks but doing so delivers Cobalt Strike beacons and will give attackers persistent access to victims’ networks.
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Since Kaseya is working on a patch to fix the flaw exploited in the attack, customers will be expecting a security update and may be fooled into installing the fake update.
Kaseya has issued a warning to all customers telling them not to open any attachments or click links in emails that claim to provide updates for the Kaseya VSA. Kaseya said any future email updates it sends to customers will not include any hyperlinks or attachments.
A similar campaign was conducted following the Colonial Pipeline ransomware attack. The emails claimed to provide system updates to detect and block ransomware attacks.
Any email received that claims to offer a security update should be treated as suspicious. Do not click links in those emails or open attachments, instead visit the software vendor’s official website to check for security updates that have been released.