CVE-2020-15701 in Apport
Summary
by MITRE • 01/25/2023
An unhandled exception in check_ignored() in apport/report.py can be exploited by a local attacker to cause a denial of service. If the mtime attribute is a string value in apport-ignore.xml, it will trigger an unhandled exception, resulting in a crash. Fixed in 2.20.1-0ubuntu2.24, 2.20.9-0ubuntu7.16, 2.20.11-0ubuntu27.6.
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Analysis
by VulDB Data Team • 01/25/2023
The vulnerability identified as CVE-2020-15701 represents a critical denial of service weakness in the apport crash reporting system used by ubuntu operating systems. This issue resides within the apport/report.py module where the check_ignored() function fails to properly handle certain data types when processing configuration files. The flaw specifically manifests when the mtime attribute within the apport-ignore.xml configuration file contains a string value instead of the expected numerical format, creating an unhandled exception that terminates the application process.
This vulnerability operates at the application level within the ubuntu desktop environment's crash reporting infrastructure, making it particularly concerning for local attackers who can leverage it to disrupt system stability. The technical root cause stems from improper input validation and type handling within the configuration parsing logic, where the code assumes the mtime attribute will always contain numerical data but fails to account for malformed string values that might be present in the ignore configuration file.
The operational impact of this vulnerability extends beyond simple service disruption as it can be exploited by local users to systematically crash the apport reporting system, potentially preventing legitimate crash reports from being processed and stored. This denial of service condition affects the system's ability to maintain proper crash reporting functionality, which is crucial for system administrators to diagnose and resolve software issues. The vulnerability affects specific versions of the apport package, with fixes available in 2.20.1-0ubuntu2.24, 2.20.9-0ubuntu7.16, and 2.20.11-0ubuntu27.6, indicating it was a widespread issue across multiple ubuntu release branches.
From a cybersecurity perspective, this vulnerability aligns with CWE-704, which addresses improper type handling in software implementations, and represents a classic example of insufficient error handling that can be exploited to create denial of service conditions. The ATT&CK framework categorizes this under privilege escalation and denial of service tactics where local adversaries can leverage application-level flaws to disrupt system services. The fix implemented by ubuntu developers required proper type checking and exception handling to ensure that string values in the mtime attribute are either properly converted or gracefully handled rather than causing application termination. This vulnerability demonstrates the importance of robust input validation in system components that process user or configuration data, particularly in security-critical infrastructure like crash reporting systems that are expected to remain stable even when encountering malformed inputs.