CVE-2016-9950 in Apport
Summary
by MITRE
An issue was discovered in Apport before 2.20.4. There is a path traversal issue in the Apport crash file "Package" and "SourcePackage" fields. These fields are used to build a path to the package specific hook files in the /usr/share/apport/package-hooks/ directory. An attacker can exploit this path traversal to execute arbitrary Python files from the local system.
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Analysis
by VulDB Data Team • 10/28/2024
The vulnerability identified as CVE-2016-9950 represents a critical path traversal flaw within the Apport crash reporting system used in Ubuntu and other Debian-based distributions. This issue affects versions prior to 2.20.4 and stems from improper validation of user-supplied input in the Package and SourcePackage fields. The Apport system is designed to collect crash information and package-specific hook files to generate detailed bug reports, making it a crucial component of the Linux desktop environment's error handling infrastructure.
The technical flaw manifests in how Apport processes the Package and SourcePackage fields during crash report generation. These fields are intended to specify the package name and source package name respectively, but the system fails to properly sanitize or validate the input before using it to construct file paths. The vulnerability allows an attacker to manipulate these fields to traverse the directory structure and access files outside the intended package hooks directory at /usr/share/apport/package-hooks/. This path traversal occurs because the system directly incorporates user input into file path construction without adequate validation or sanitization mechanisms.
The operational impact of this vulnerability is severe as it enables arbitrary code execution on the local system. An attacker who can influence the Package or SourcePackage fields in a crash report can potentially execute malicious Python code from the local filesystem. This represents a privilege escalation vector that could be exploited by local users to gain unauthorized access to system resources, execute arbitrary commands, or compromise the integrity of the crash reporting system itself. The vulnerability is particularly dangerous because it leverages the legitimate functionality of Apport, making it harder to detect and potentially allowing attackers to bypass security controls that might otherwise prevent such attacks.
This vulnerability maps to CWE-22 Path Traversal and aligns with several ATT&CK techniques including T1059 Command and Scripting Interpreter for executing code and T1068 Exploitation for Windows and T1078 Valid Accounts for privilege escalation. The attack chain typically involves crafting a malicious crash report with manipulated Package or SourcePackage fields that, when processed by Apport, result in the execution of arbitrary Python code from the system. The vulnerability demonstrates a classic lack of input validation in system components that handle user-supplied data, a pattern commonly seen in security flaws affecting system utilities and reporting mechanisms. The fix implemented in Apport 2.20.4 involves proper sanitization of the Package and SourcePackage fields to prevent directory traversal attacks, ensuring that user input cannot be used to access files outside the intended package hooks directory structure. Organizations should ensure their systems are updated to Apport version 2.20.4 or later to mitigate this risk, as the vulnerability could be exploited by local attackers to compromise system integrity and potentially escalate privileges.