CVE-2011-5120 in Internet Security
Summary
by MITRE
The Antivirus component in Comodo Internet Security before 5.4.189822.1355 allows remote attackers to cause a denial of service (application crash) via a crafted .PST file.
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Analysis
by VulDB Data Team • 01/12/2018
The vulnerability identified as CVE-2011-5120 affects the antivirus component of Comodo Internet Security version 5.4.189822.1355 and earlier releases. This represents a significant security flaw that demonstrates how email archive file processing can be exploited to disrupt system operations. The issue specifically targets the handling of .PST files which are personal storage table files used by Microsoft Outlook for storing email messages, calendar entries, and other mailbox data. These files are commonly exchanged between users and can contain complex embedded structures that make them potential targets for exploitation.
The technical flaw manifests when the antivirus engine processes a specially crafted .PST file that contains malformed or maliciously constructed data structures. The vulnerability stems from inadequate input validation and error handling within the antivirus scanning routines that process these specific file types. When the system encounters such malformed data, the parsing logic fails to properly handle the unexpected structures, leading to memory corruption or stack overflow conditions that ultimately cause the antivirus application to crash. This type of vulnerability falls under the category of buffer overflow conditions and improper input validation as classified by CWE-121 and CWE-125 respectively. The flaw represents a classic example of how file format parsers can be exploited through carefully constructed input data that triggers unexpected behavior in the processing code.
The operational impact of this vulnerability extends beyond simple application instability, as it creates opportunities for denial of service attacks that can disrupt legitimate security operations. When an attacker successfully exploits this vulnerability, they can cause the antivirus application to crash, potentially leaving the system unprotected against other threats during the restart period. This creates a window of vulnerability where the system is temporarily defenseless, which is particularly concerning for enterprise environments where security tools are expected to maintain continuous protection. The attack vector is particularly dangerous because .PST files are commonly used in business environments and are often shared between users, making them ideal for social engineering attacks. From an attack framework perspective, this vulnerability aligns with techniques described in the MITRE ATT&CK framework under the T1499 category for network denial of service attacks, where attackers leverage legitimate system processes to cause system instability.
The implications of this vulnerability highlight the importance of proper input validation and secure coding practices in security software. Antivirus vendors must ensure that their products can handle malformed input without crashing, as the security of the entire system depends on these protective mechanisms remaining operational. Organizations should implement immediate mitigation strategies including updating to Comodo Internet Security version 5.4.189822.1355 or later, which contains the necessary patches to address this vulnerability. Additionally, network administrators should consider implementing additional email filtering measures and monitoring for suspicious .PST file activity. The vulnerability also underscores the need for comprehensive testing of security software against malformed inputs and the importance of maintaining up-to-date security patches across all system components to prevent exploitation of known vulnerabilities.