CVE-2018-12243 in Messaging Gateway
Summary
by MITRE
The Symantec Messaging Gateway product prior to 10.6.6 may be susceptible to a XML external entity (XXE) exploit, which is a type of issue where XML input containing a reference to an external entity is processed by a weakly configured XML parser. The attack uses file URI schemes or relative paths in the system identifier to access files that should not normally be accessible.
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Analysis
by VulDB Data Team • 03/25/2020
The Symantec Messaging Gateway product vulnerability CVE-2018-12243 represents a critical XML external entity processing flaw that affects versions prior to 10.6.6. This vulnerability falls under the CWE-611 category of Improper Restriction of XML External Entity Reference, which is a well-documented weakness in XML processing implementations. The flaw enables attackers to exploit the XML parser's handling of external entities, creating a pathway for unauthorized file access and potential system compromise. The vulnerability specifically manifests when the messaging gateway processes XML input that contains references to external entities, allowing malicious actors to manipulate the parsing behavior through crafted XML payloads.
The technical exploitation of this XXE vulnerability occurs when the Symantec Messaging Gateway receives XML data that includes external entity declarations in the system identifier. Attackers can leverage file URI schemes or relative path traversal techniques to access sensitive files on the underlying system that should normally be restricted. This includes accessing configuration files, credential stores, system logs, and potentially even system binaries or database files. The parser's weak configuration allows it to resolve external entity references without proper validation, creating a direct pathway for information disclosure and potential privilege escalation. The vulnerability is particularly dangerous because it operates at the XML parsing layer, meaning it can be triggered through various communication channels that utilize XML processing within the messaging gateway's architecture.
The operational impact of this vulnerability extends beyond simple information disclosure, as it can enable attackers to gain unauthorized access to sensitive data and potentially compromise the entire messaging infrastructure. Organizations using affected Symantec Messaging Gateway versions face risks including credential theft, system configuration exposure, and potential lateral movement within their network environments. The vulnerability can be exploited through various attack vectors including email processing, API interactions, or any communication channel that involves XML data handling within the gateway. This creates a significant risk for enterprises that rely on the messaging gateway for email security and content filtering, as the compromise of this system can lead to widespread data exposure and service disruption.
Organizations should immediately implement mitigations including upgrading to Symantec Messaging Gateway version 10.6.6 or later, which contains the necessary patches to address the XXE vulnerability. Network segmentation and firewall rules should be implemented to restrict access to the messaging gateway from untrusted networks, while input validation and sanitization measures should be strengthened to prevent malicious XML data from reaching the vulnerable parsing components. Security monitoring should be enhanced to detect unusual XML processing patterns or attempts to access restricted file paths. Additionally, organizations should conduct comprehensive vulnerability assessments to identify any other systems that might be susceptible to similar XXE vulnerabilities, as this type of flaw is commonly found in legacy applications and can be exploited across multiple software components within enterprise environments. The ATT&CK framework categorizes this vulnerability under T1190 - Exploit Public-Facing Application, highlighting the need for proper application hardening and input validation controls to prevent exploitation.