CVE-2008-2266 in nzbget
Summary
by MITRE
uulib/uunconc.c in UUDeview 0.5.20, as used in nzbget before 0.3.0 and possibly other products, allows local users to overwrite arbitrary files via a symlink attack on a temporary filename generated by the tempnam function. NOTE: this may be a CVE-2004-2265 regression.
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Analysis
by VulDB Data Team • 08/15/2019
The vulnerability identified as CVE-2008-2266 represents a critical file system security flaw affecting UUDeview 0.5.20 and its integration in nzbget versions prior to 0.3.0. This issue stems from improper handling of temporary file creation within the uulib/uunconc.c component, creating an exploitable condition that enables local attackers to perform privilege escalation through malicious symlink manipulation. The flaw specifically targets the tempnam function which generates temporary filenames without adequate security measures to prevent predictable path exploitation.
The technical implementation of this vulnerability exploits the predictable nature of temporary file generation in Unix-like systems where the tempnam function creates filenames based on a fixed pattern that can be anticipated by local attackers. When UUDeview processes uuencoded files, it creates temporary files using this function which can be manipulated through symbolic link attacks. An attacker with local access can create malicious symbolic links in the directory where temporary files are generated, causing the vulnerable application to write data to unintended locations. This represents a classic race condition vulnerability where the timing window between temporary file creation and file access can be exploited to redirect file operations.
From an operational perspective, this vulnerability poses significant risk to systems where nzbget or UUDeview is installed with elevated privileges or where local users have access to the system. The impact extends beyond simple file overwrites to potentially allow attackers to modify critical system files, configuration data, or even inject malicious code into legitimate processes. The vulnerability's classification aligns with CWE-377: Insecure Temporary File and CWE-378: Use of Insecure Temporary Files, both of which fall under the broader category of insecure file handling practices that can lead to privilege escalation and data integrity compromise.
The exploitation of CVE-2008-2266 demonstrates characteristics consistent with attack patterns found in the ATT&CK framework under the T1059.007 technique for Command and Scripting Interpreter: PowerShell and T1548.001 for Abuse of Functionality. The vulnerability creates opportunities for attackers to escalate privileges through file system manipulation, potentially leading to persistent access or further system compromise. Organizations running affected versions of nzbget or systems utilizing UUDeview 0.5.20 should consider this vulnerability as a potential entry point for lateral movement within their network infrastructure.
Mitigation strategies for this vulnerability require immediate patching of affected software versions to address the improper temporary file handling mechanism. System administrators should ensure that all instances of nzbget are updated to version 0.3.0 or later where this regression has been resolved. Additionally, implementing proper file system permissions and directory access controls can help limit the impact of potential exploitation attempts. The fix typically involves modifying the temporary file creation process to use secure methods such as mkstemp or similar functions that provide atomic creation with proper access controls, thereby eliminating the race condition that enables symlink attacks. Organizations should also conduct vulnerability assessments to identify other potentially affected applications that may be using similar insecure temporary file handling patterns, as this represents a common security weakness in software development practices.