CVE-2017-14177 in Apport
Summary
by MITRE
Apport through 2.20.7 does not properly handle core dumps from setuid binaries allowing local users to create certain files as root which an attacker could leverage to perform a denial of service via resource exhaustion or possibly gain root privileges. NOTE: this vulnerability exists because of an incomplete fix for CVE-2015-1324.
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Analysis
by VulDB Data Team • 02/03/2023
The vulnerability identified as CVE-2017-14177 affects Apport version 2.20.7 and earlier, representing a significant security flaw in how the system handles core dump processing for setuid binaries. This issue stems from an incomplete remediation of a previous vulnerability CVE-2015-1324, creating a persistent weakness in the system's privilege management and file creation mechanisms. The flaw specifically manifests when Apport processes core dumps generated by setuid programs, which are designed to run with elevated privileges. This creates an opportunity for local attackers to exploit the system's handling of these core files and potentially manipulate file creation processes that should normally be restricted to root access.
The technical mechanism behind this vulnerability involves Apport's improper validation of core dump contents when dealing with setuid binaries. When such binaries crash and generate core dumps, the Apport service processes these files to gather debugging information. However, due to inadequate checks in the processing logic, the system fails to properly sanitize the core dump data before attempting to create or modify files on the filesystem. This failure allows local users to influence the file creation process in a way that can result in files being created with root ownership, bypassing normal privilege restrictions. The vulnerability operates under the CWE-22 principle of improper limitation of a pathname to a restricted directory, where the path manipulation allows unauthorized file creation with elevated privileges.
The operational impact of this vulnerability extends beyond simple privilege escalation to include potential denial of service scenarios. An attacker could leverage this flaw to create specific files as root, potentially exhausting system resources through repeated file creation or by creating malicious files that interfere with system operations. The resource exhaustion attack vector could involve creating numerous large files or directories that consume disk space or memory resources, effectively preventing legitimate system operations. Additionally, the privilege escalation capability presents a serious threat where attackers might create malicious files that could be executed with root privileges, potentially leading to complete system compromise. This vulnerability directly aligns with ATT&CK technique T1068 which covers local privilege escalation through the exploitation of system vulnerabilities.
The mitigation strategies for this vulnerability involve immediate patching of Apport to version 2.20.8 or later, which contains the complete fix for both CVE-2015-1324 and CVE-2017-14177. System administrators should also implement monitoring of core dump processing activities and file creation patterns that occur with elevated privileges. Additional protective measures include restricting access to core dump directories and implementing proper file system permissions that prevent unauthorized modification of system-critical files. The fix addresses the underlying issue by implementing proper validation of core dump contents and ensuring that file creation operations maintain appropriate privilege boundaries when processing setuid binary crashes. Organizations should also consider implementing automated vulnerability scanning to identify systems running vulnerable versions of Apport and ensure timely remediation across their infrastructure.