CVE-2005-2768 in Sophos
Summary
by MITRE
Heap-based buffer overflow in the Sophos Antivirus Library, as used by Sophos Antivirus, PureMessage, MailMonitor, and other products, allows remote attackers to execute arbitrary code via a Visio file with a crafted sub record length.
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Analysis
by VulDB Data Team • 07/03/2019
The vulnerability identified as CVE-2005-2768 represents a critical heap-based buffer overflow within the Sophos Antivirus Library component that affects multiple Sophos security products including Sophos Antivirus, PureMessage, and MailMonitor. This flaw resides in the library's handling of Visio file formats, specifically when processing crafted sub record lengths that exceed the allocated buffer boundaries. The vulnerability stems from insufficient input validation and bounds checking within the file parsing mechanism, creating an exploitable condition where maliciously constructed Visio files can trigger memory corruption. The heap-based nature of the overflow indicates that the vulnerability occurs within dynamically allocated memory regions, making exploitation more complex but potentially more reliable than stack-based counterparts. Attackers can leverage this weakness by constructing Visio files with deliberately oversized sub record length fields that cause the library to write beyond allocated memory boundaries, potentially leading to arbitrary code execution.
The technical implementation of this vulnerability involves the Sophos Antivirus Library's parsing routine for Visio file structures where it reads sub record length fields without proper validation against maximum buffer sizes. When a malicious Visio file contains a sub record length that exceeds the expected buffer capacity, the library's memory management routines write data beyond the allocated heap space, causing buffer overflow conditions. This type of vulnerability typically manifests when the application performs operations such as memcpy, strcpy, or similar functions without verifying that the source data length fits within the destination buffer. The flaw directly maps to CWE-121, which describes heap-based buffer overflow conditions, and represents a classic example of inadequate input validation in file format parsers. The vulnerability's remote exploitation capability means that attackers can deliver malicious Visio files through email attachments, web downloads, or other network-based delivery mechanisms without requiring local system access.
The operational impact of CVE-2005-2768 extends beyond simple code execution to encompass potential system compromise and data breaches across organizations relying on Sophos security solutions. When successfully exploited, the buffer overflow can allow attackers to execute arbitrary code with the privileges of the affected application process, typically resulting in full system compromise if the vulnerable software runs with elevated permissions. The widespread deployment of affected Sophos products across enterprise environments means that a single compromised system could serve as a foothold for broader network infiltration. Organizations utilizing PureMessage and MailMonitor products face particular risk as these solutions often process email attachments automatically, making them prime targets for phishing campaigns that leverage this vulnerability. The exploitation process typically involves crafting Visio files that trigger the buffer overflow during normal file processing, potentially bypassing traditional security controls that rely on signature-based detection methods.
Mitigation strategies for CVE-2005-2768 require immediate action from affected organizations to address the vulnerability through multiple layers of security controls. The primary recommendation involves applying official patches released by Sophos to update the vulnerable Antivirus Library components, which directly addresses the root cause of the buffer overflow condition. Network administrators should implement email filtering rules to block Visio files from untrusted sources and consider implementing sandboxing mechanisms for file processing. The principle of least privilege should be enforced by running vulnerable applications with minimal required permissions, limiting potential damage from successful exploitation attempts. Security monitoring should include detection of anomalous file processing activities and unusual memory allocation patterns that may indicate exploitation attempts. Organizations should also consider implementing network segmentation to limit lateral movement if exploitation occurs, and maintain regular backups to ensure rapid recovery from potential compromise. The vulnerability's classification under ATT&CK technique T1059.007 for command and script interpreter execution highlights the need for comprehensive endpoint detection and response capabilities to identify and block malicious code execution attempts. Additionally, regular vulnerability assessments and penetration testing should be conducted to identify similar weaknesses in other software components that may present analogous security risks.