CVE-2010-3136 in Skype
Summary
by MITRE
Untrusted search path vulnerability in Skype 4.2.0.169 and earlier allows local users, and possibly remote attackers, to execute arbitrary code and conduct DLL hijacking attacks via a Trojan horse wab32.dll that is located in the same folder as a .skype file.
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Analysis
by VulDB Data Team • 03/11/2017
The vulnerability identified as CVE-2010-3136 represents a critical untrusted search path issue affecting Skype versions 4.2.0.169 and earlier. This flaw stems from Skype's improper handling of dynamic link library (DLL) loading mechanisms when processing .skype files, creating a pathway for malicious code execution through DLL hijacking techniques. The vulnerability specifically manifests when a malicious wab32.dll file is placed in the same directory as a .skype file, exploiting the application's trust in local directory paths during DLL resolution.
The technical exploitation of this vulnerability aligns with CWE-427, which addresses uncontrolled search path vulnerabilities, and CWE-428, which covers untrusted search path conditions. The flaw operates by leveraging the Windows DLL loading order, where applications first search the current working directory before examining system directories. When Skype processes a .skype file, it may inadvertently load the malicious wab32.dll from the local directory rather than the legitimate system location, allowing attackers to execute arbitrary code with the privileges of the victim user. This vulnerability demonstrates the classic attack pattern described in the ATT&CK framework under T1059.001 for execution through command and scripting interpreters, and T1574.001 for hijacking execution flow through dynamic link library injection.
The operational impact of CVE-2010-3136 extends beyond simple code execution to encompass potential privilege escalation and persistent system compromise. Local attackers can leverage this vulnerability to gain unauthorized access to systems, while remote attackers might exploit it through social engineering campaigns that trick users into opening malicious .skype files. The vulnerability affects the core communication functionality of Skype, potentially enabling man-in-the-middle attacks, data exfiltration, and unauthorized access to user communications. The attack vector is particularly concerning because it requires minimal user interaction beyond opening a .skype file, making it an attractive target for phishing campaigns and other social engineering attacks.
Mitigation strategies for CVE-2010-3136 should focus on both immediate remediation and long-term architectural improvements. The most effective immediate solution involves upgrading to Skype versions that address this vulnerability, as the original affected versions are no longer supported. System administrators should implement strict file access controls and directory permissions to limit write access to Skype installation directories and user working directories containing .skype files. Additionally, security measures should include disabling automatic execution of files from untrusted sources, implementing application whitelisting policies, and conducting regular security audits of system directories. The vulnerability also highlights the importance of secure coding practices and proper DLL loading mechanisms, which can be addressed through adherence to secure development guidelines and regular security testing of applications. Organizations should also consider implementing network-based protections such as intrusion detection systems to monitor for suspicious file access patterns and potential exploitation attempts.