CVE-2013-6435 in RPM Package Manager
Summary
by MITRE
Race condition in RPM 4.11.1 and earlier allows remote attackers to execute arbitrary code via a crafted RPM file whose installation extracts the contents to temporary files before validating the signature, as demonstrated by installing a file in the /etc/cron.d directory.
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Analysis
by VulDB Data Team • 03/01/2022
The vulnerability identified as CVE-2013-6435 represents a critical race condition flaw within the RPM package management system affecting versions 4.11.1 and earlier. This vulnerability stems from the improper handling of temporary file operations during package installation processes, creating exploitable conditions that allow remote attackers to execute arbitrary code on affected systems. The race condition occurs when RPM extracts package contents to temporary directories before performing signature validation, enabling malicious actors to manipulate the installation process through carefully crafted RPM files.
The technical implementation of this vulnerability exploits the fundamental timing gap between file extraction and signature verification within RPM's package installation workflow. During normal operation, RPM creates temporary files in predictable locations such as /tmp or other temporary directories before validating the package signature. This temporal window provides attackers with an opportunity to substitute legitimate files with malicious counterparts, particularly targeting system directories like /etc/cron.d where the extracted files will be moved or executed. The flaw specifically manifests when RPM processes packages that contain files destined for sensitive system directories, as demonstrated by the exploitation technique targeting cron directory installations.
From an operational security perspective, this vulnerability presents a severe risk to systems running affected RPM versions as it enables privilege escalation and arbitrary code execution without requiring local access or authentication. Attackers can craft malicious RPM packages that appear legitimate during signature validation but contain malicious payloads that execute with the privileges of the package installation process. The impact extends beyond simple code execution to potential system compromise, as the vulnerability allows attackers to place malicious files in critical system directories such as /etc/cron.d, which could lead to persistent backdoor installations or system-wide compromise. This vulnerability particularly affects enterprise systems and servers where RPM-based package management is prevalent, making it a significant concern for system administrators and security teams.
The mitigation strategies for CVE-2013-6435 involve immediate patching of RPM packages to versions that address the race condition through proper synchronization of file extraction and signature validation processes. System administrators should prioritize updating all affected systems to RPM versions 4.11.2 or later, which contain fixes that eliminate the temporal gap between file extraction and signature verification. Additional protective measures include implementing strict file system permissions for temporary directories, monitoring package installation processes for suspicious activity, and employing automated vulnerability scanning tools to identify systems running vulnerable RPM versions. Organizations should also consider implementing package integrity verification mechanisms and restricting package installation privileges to minimize potential exploitation impact. This vulnerability aligns with CWE-367, which addresses Time-of-Check to Time-of-Use (TOCTOU) race conditions, and maps to ATT&CK technique T1059.007 for execution through command and scripting interpreter, as the vulnerability enables attackers to execute malicious code through compromised package installation processes.