Google’s Threat Analysis Group revealed on Thursday that it discovered and worked to help patch an email server flaw used to steal data from governments in Greece, Moldova, Tunisia, Vietnam and Pakistan. The exploit, known as CVE-2023-37580, targeted email server Zimbra Collaboration to pilfer email data, user credentials and authentication tokens from organizations.
It started in Greece at the end of June. Attackers that discovered the vulnerability and sent emails to a government organization containing the exploit. If someone clicked the link while logged into their Zimbra account, it automatically stole email data and set up auto-forwarding to take control of the address.
While Zimbra published a hotfix on open source platform Github on July 5, most of the activity deploying the exploit happened afterward. That means targets didn’t get around to updating the software with the fix until it was too late. It’s a good reminder to update the devices you’ve been ignoring now, and ASAP as more updates become available. “These campaigns also highlight how attackers monitor open-source repositories to opportunistically exploit vulnerabilities where the fix is in the repository, but not yet released to users,” the Google Threat Analysis Group wrote in a blog post.
Around mid-July, it became clear that threat group Winter Vivern got ahold of the exploit. Winter Vivern targeted government organizations in Moldova and Tunisia. Then, a third unknown actor used the exploit to phish for credentials from members of the Vietnam government. That data got published to an official government domain, likely run by the attackers. The final campaign Google’s Threat Analysis Group detailed targeted a government organization in Pakistan to steal Zimbra authentication tokens, a secure piece of information used to access locked or protected information.
Zimbra users were also the target of a mass-phishing campaign earlier this year. Starting in April, an unknown threat actor sends an email with a phishing link in an HTML file, according to ESET researchers. Before that, in 2022, threat actors used a different Zimbra exploit to steal emails from European government and media organizations.
As of 2022, Zimbra said it had more than 200,000 customers, including over 1,000 government organizations. “The popularity of Zimbra Collaboration among organizations expected to have lower IT budgets ensures that it stays an attractive target for adversaries,” ESET researchers said about why attackers target Zimbra.