Zimbra Collaboration Suite SSRF (CVE-2020-7796)
Description
Zimbra Collaboration Suite versions prior to 8.8.15 Patch 7 contain a Server-Side Request Forgery (SSRF) vulnerability that allows unauthenticated remote attackers to force the server to make HTTP requests to arbitrary internal or external hosts. This vulnerability exists due to insufficient validation of user-supplied URLs in a component of the Zimbra application, enabling attackers to abuse the server as a proxy for malicious requests.
Remediation
Immediately upgrade Zimbra Collaboration Suite to version 8.8.15 Patch 7 or later, which addresses this vulnerability. Follow these steps:
1. Review the official Zimbra release notes and upgrade documentation at https://wiki.zimbra.com/wiki/Zimbra_Releases/8.8.15/P7
2. Schedule a maintenance window and create a complete backup of your Zimbra installation and data
3. Test the upgrade process in a non-production environment first
4. Apply the patch or perform the upgrade following Zimbra's official procedures
5. After upgrading, verify the patch level using the zmcontrol -v command
6. Monitor application logs for any anomalous behavior post-upgrade
As a temporary mitigation if immediate patching is not possible, implement network-level controls to restrict outbound connections from the Zimbra server to only necessary destinations, and monitor for suspicious DNS queries or outbound HTTP requests.