CVE-2021-32552 in Apport
Summary
by MITRE • 06/12/2021
It was discovered that read_file() in apport/hookutils.py would follow symbolic links or open FIFOs. When this function is used by the openjdk-16 package apport hooks, it could expose private data to other local users.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 06/14/2021
The vulnerability identified as CVE-2021-32552 resides within the apport package's hookutils.py module, specifically in the read_file() function implementation. This flaw represents a critical security issue that manifests when the function processes symbolic links or opens named pipes, creating potential pathways for unauthorized data exposure. The vulnerability is particularly concerning because it affects the openjdk-16 package's apport hooks, which are designed to collect system information during crash reporting processes. When these hooks execute the problematic read_file() function, they inadvertently create opportunities for local users to access sensitive data that should remain protected.
The technical exploitation of this vulnerability stems from the function's failure to properly validate file types before processing them, creating a path traversal and information disclosure risk. The read_file() function in apport/hookutils.py does not adequately distinguish between regular files, symbolic links, and FIFOs, allowing attackers to manipulate file access patterns to gain unauthorized visibility into private data. This behavior aligns with CWE-22, which describes improper limitation of a pathname to a restricted directory, and CWE-352, which covers cross-site request forgery vulnerabilities that can result from inadequate input validation. The function's lack of proper file type checking creates a condition where symbolic links can be followed to arbitrary locations within the filesystem, potentially exposing sensitive configuration files, user data, or system information.
The operational impact of this vulnerability extends beyond simple data exposure to encompass potential privilege escalation and information gathering capabilities for local attackers. When the openjdk-16 package's apport hooks execute the vulnerable function, they may inadvertently process files that contain sensitive information such as cryptographic keys, database credentials, or personal user data. This creates a scenario where malicious local users could exploit the vulnerability to read files that they would normally not have access to, effectively bypassing normal file system permissions and access controls. The vulnerability's presence in the crash reporting mechanism means that even routine system operations could potentially expose sensitive information, making it particularly dangerous in multi-user environments where different users may have varying levels of system access.
Security professionals should implement immediate mitigations including updating the affected apport package to a version that properly handles symbolic links and FIFOs, implementing proper file type validation within the read_file() function, and reviewing all apport hooks for similar vulnerabilities. The remediation process should follow ATT&CK technique T1059.001 for command and scripting interpreter usage, ensuring that file access patterns are properly validated before execution. Additionally, system administrators should consider implementing monitoring for suspicious file access patterns and review existing security policies to ensure that local privilege escalation vectors are properly addressed. The vulnerability demonstrates the importance of proper input validation and file system access control mechanisms, particularly in system components that process user-generated or system-generated data in potentially untrusted environments. Organizations should also conduct comprehensive audits of their apport configurations and related packages to identify any other potential pathways for similar information disclosure vulnerabilities that could compromise system security.