CVE-2019-6980 in Zimbra Collaboration Suite
Summary
by MITRE
Synacor Zimbra Collaboration Suite 8.7.x through 8.8.11 allows insecure object deserialization in the IMAP component.
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Analysis
by VulDB Data Team • 09/25/2023
The Synacor Zimbra Collaboration Suite represents a widely deployed email and collaboration platform that serves enterprise organizations globally. This particular vulnerability affects versions 8.7.x through 8.8.11, indicating a substantial attack surface across multiple releases. The insecure object deserialization flaw exists within the IMAP component, which is fundamental to email access and synchronization protocols. This component handles incoming email data and user authentication requests, making it a critical entry point for potential attackers seeking to compromise the system. The vulnerability stems from the application's improper handling of serialized objects during the IMAP protocol processing, creating opportunities for remote code execution and privilege escalation attacks.
The technical flaw manifests through the deserialization of untrusted data without adequate validation or sanitization. When the IMAP component receives serialized objects from external sources, it fails to implement proper security controls to verify the integrity and authenticity of these objects before processing them. This vulnerability maps directly to CWE-502, which specifically addresses deserialization of untrusted data as a security weakness. Attackers can exploit this by crafting malicious serialized objects that, when processed by the vulnerable Zimbra installation, trigger arbitrary code execution on the target system. The deserialization process typically involves converting serialized data structures back into executable objects, but without proper input validation, malicious payloads can be executed with the privileges of the running service.
The operational impact of this vulnerability extends beyond simple remote code execution to encompass potential system compromise and data breaches. An attacker who successfully exploits this vulnerability can gain unauthorized access to email accounts, read sensitive communications, modify email content, and potentially escalate privileges to system administrator levels. The IMAP component's role in email processing means that successful exploitation could lead to widespread data compromise across an organization's email infrastructure. Additionally, the vulnerability could enable attackers to establish persistent access through backdoor creation or privilege escalation techniques, making it particularly dangerous for enterprise environments where email systems often serve as primary communication channels and contain sensitive business information.
Organizations should implement immediate mitigations including updating to patched versions of Zimbra Collaboration Suite, as Synacor has released security updates addressing this specific vulnerability. Network segmentation and firewall rules should be configured to limit access to IMAP services, particularly from untrusted networks. Input validation controls should be implemented at the application level to sanitize all serialized data before processing, and the principle of least privilege should be enforced for the IMAP service accounts. Security monitoring should be enhanced to detect unusual patterns in IMAP traffic and potential exploitation attempts. From an ATT&CK framework perspective, this vulnerability aligns with techniques such as T1059.007 for remote code execution and T1078 for valid accounts usage, while also potentially enabling techniques like T1566 for initial access through email-based attacks. Regular security assessments and vulnerability scanning should be conducted to identify similar deserialization vulnerabilities in other components of the email infrastructure.