CVE-2010-3126 in Avast Antivirus Free
Summary
by MITRE
Untrusted search path vulnerability in avast! Free Antivirus version 5.0.594 and earlier allows local users, and possibly remote attackers, to execute arbitrary code and conduct DLL hijacking attacks via a Trojan horse mfc90loc.dll that is located in the same folder as an avast license (.avastlic) file.
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Analysis
by VulDB Data Team • 01/07/2018
The vulnerability identified as CVE-2010-3126 represents a critical untrusted search path issue within avast! Free Antivirus version 5.0.594 and earlier implementations. This flaw stems from the software's improper handling of dynamic link library (dll) loading mechanisms during the processing of license files, creating a dangerous execution environment where malicious code can be injected. The vulnerability specifically manifests when the antivirus software encounters an avast license file (.avastlic) and subsequently searches for supporting dll files in the same directory, without adequate validation of the source or authenticity of these components.
The technical exploitation of this vulnerability relies on the principle of DLL hijacking, where an attacker places a maliciously crafted dll file named mfc90loc.dll in the same directory as a legitimate avast license file. When the vulnerable antivirus software attempts to process the license file, it loads the malicious dll from the local directory rather than from the intended system locations. This behavior directly violates security principles and creates a pathway for privilege escalation and arbitrary code execution. The vulnerability's classification under CWE-427 indicates an uncontrolled search path, where the application's search path includes the current working directory, enabling attackers to influence which libraries are loaded.
The operational impact of this vulnerability extends beyond simple local privilege escalation, as it can potentially be exploited by remote attackers who can manipulate the target environment through various delivery mechanisms. The attack surface is particularly concerning given that avast! Free Antivirus is widely deployed across enterprise and consumer environments, making the exploitation vector highly relevant for threat actors seeking persistent access to systems. The vulnerability demonstrates how seemingly benign file processing operations can create dangerous execution contexts, particularly when applications fail to implement proper dll loading security measures. Attackers can leverage this weakness to execute malicious code with the privileges of the affected user, potentially leading to complete system compromise.
Mitigation strategies for CVE-2010-3126 should focus on immediate remediation through official software updates provided by avast Free Antivirus are updated to patched versions that properly validate dll loading paths. The implementation of application whitelisting and strict file permission controls can help prevent unauthorized dll placement in critical directories. Additionally, system administrators should consider deploying behavioral monitoring solutions that can detect suspicious dll loading patterns and unauthorized file modifications. According to ATT&CK framework, this vulnerability maps to techniques involving privilege escalation and persistence through malicious code injection, making it a significant concern for defensive security operations that must account for both local and remote attack vectors.