CVE-2005-2300 in Skype
Summary
by MITRE
Skype 1.1.0.20 and earlier allows local users to overwrite arbitrary files via a symlink attack on the skype_profile.jpg temporary file.
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Analysis
by VulDB Data Team • 07/03/2019
This vulnerability exists in Skype version 1.1.0.20 and earlier, representing a classic file system race condition and symlink attack scenario. The flaw occurs during Skype's initialization process when it creates a temporary file named skype_profile.jpg without proper validation of the file path or existence check. Local attackers can exploit this by creating a symbolic link with the same name in the target directory, causing Skype to write sensitive data to an attacker-controlled location instead of the intended temporary file. This represents a CWE-59 vulnerability related to improper handling of symbolic links and a CWE-22 weakness in improper limitation of a pathname to a restricted directory. The vulnerability falls under the ATT&CK technique T1059 for execution through command and scripting interpreter, as it enables arbitrary file overwrites that could lead to privilege escalation or code execution.
The technical implementation of this attack involves the attacker creating a symbolic link pointing to a file of their choice before Skype attempts to create the temporary file. When Skype runs and attempts to write to skype_profile.jpg, the system follows the symbolic link and writes data to the target file instead of the intended temporary location. This creates a race condition where the timing of file creation and symbolic link establishment determines successful exploitation. The vulnerability is particularly dangerous because it allows attackers to overwrite files with arbitrary content, potentially including system configuration files, user data, or even executable components that could be leveraged for privilege escalation.
The operational impact of this vulnerability extends beyond simple file overwrites and represents a significant security risk for local users who may not realize they are vulnerable to such attacks. Attackers could potentially overwrite critical system files, configuration data, or user documents with malicious content. The vulnerability is particularly concerning in environments where users have local access to systems running Skype, as it provides a vector for privilege escalation when combined with other attack techniques. This flaw could be exploited as part of a broader attack chain to establish persistent access or escalate privileges within the system.
Mitigation strategies for this vulnerability involve multiple layers of defense and system hardening measures. The most effective immediate solution is to upgrade to Skype versions that address this race condition by implementing proper file path validation and avoiding the creation of temporary files in predictable locations. System administrators should also implement proper file system permissions and access controls to limit the impact of such attacks. Additional mitigations include disabling unnecessary symbolic link creation capabilities, implementing file integrity monitoring systems, and conducting regular security audits of applications that create temporary files. Organizations should also consider implementing application whitelisting policies to prevent unauthorized execution of potentially malicious files. The vulnerability demonstrates the critical importance of proper temporary file handling and the need for applications to validate file paths and implement secure coding practices to prevent such race conditions.