CVE-2017-8843 in lrzip
Summary
by MITRE
The join_pthread function in stream.c in liblrzip.so in lrzip 0.631 allows remote attackers to cause a denial of service (NULL pointer dereference and application crash) via a crafted archive.
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Analysis
by VulDB Data Team • 12/06/2022
The vulnerability identified as CVE-2017-8843 resides within the lrzip compression utility version 0.631, specifically in the liblrzip.so library's stream.c component. This flaw manifests in the join_pthread function which handles thread joining operations during archive processing. The issue arises when remote attackers craft malicious archive files that trigger a NULL pointer dereference condition, leading to application crashes and denial of service. The vulnerability represents a critical weakness in the software's input validation and error handling mechanisms, as it fails to properly validate archive structures before processing thread operations.
This vulnerability operates at the intersection of memory safety and thread management within compression utilities, making it particularly dangerous in environments where automated archive processing occurs. The NULL pointer dereference occurs when the join_pthread function attempts to access a memory location that has not been properly initialized or allocated, causing the application to terminate abruptly. The attack vector is remote since attackers can submit crafted archives to systems that process lrzip files, potentially affecting web services, automated backup systems, or any application that utilizes lrzip for archive handling. This flaw directly maps to CWE-476 which defines NULL Pointer Dereference as a condition where a null value is dereferenced, and represents a fundamental memory safety issue that has been consistently identified as a critical threat in software security.
The operational impact of CVE-2017-8843 extends beyond simple application crashes to encompass broader service availability concerns and potential system stability issues. When exploited, this vulnerability can cause cascading failures in systems that depend on lrzip for data compression, particularly affecting services that process user-uploaded archives or automated backup processes. The denial of service condition can be particularly severe in environments where lrzip is used as a backend component for file transfer systems, cloud storage services, or enterprise backup solutions. From an attack framework perspective, this vulnerability aligns with ATT&CK technique T1499.004 which covers Network Denial of Service, and T1059.007 which addresses Command and Scripting Interpreter for PowerShell, as it can be leveraged to disrupt automated processing pipelines that utilize lrzip functionality. The vulnerability's exploitation does not require elevated privileges, making it accessible to any attacker who can submit malicious archives to vulnerable systems.
Mitigation strategies for CVE-2017-8843 should focus on both immediate patching and defensive measures. The most effective solution involves upgrading to lrzip version 0.632 or later, which includes the necessary fixes to properly validate archive structures before thread operations. Organizations should implement strict input validation for all archive files processed through lrzip, including signature verification and content sanitization before decompression. Network-based defenses can include implementing content filtering for archive files, particularly those with lrzip extensions, to prevent potentially malicious archives from reaching vulnerable systems. Additionally, system administrators should consider implementing monitoring and alerting for application crashes or abnormal termination patterns that may indicate exploitation attempts. The vulnerability highlights the importance of proper error handling in multi-threaded applications and underscores the need for comprehensive testing of edge cases in compression utilities. Security teams should also consider implementing sandboxing techniques for archive processing to isolate potential exploitation attempts and prevent broader system compromise.