CVE-2017-8845 in LZO
Summary
by MITRE
The lzo1x_decompress function in lzo1x_d.ch in LZO 2.08, as used in lrzip 0.631, allows remote attackers to cause a denial of service (invalid memory read and application crash) via a crafted archive.
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Analysis
by VulDB Data Team • 12/06/2022
The vulnerability identified as CVE-2017-8845 resides within the lzo1x_decompress function implementation in the lzo1x_d.ch file of LZO compression library version 2.08. This flaw specifically affects lrzip 0.631 which utilizes this compression library for handling archived data. The vulnerability manifests when the decompression function processes malformed or crafted archive files that contain invalid memory references during the decompression operation. The issue stems from insufficient input validation and error handling within the decompression routine, which fails to properly validate the integrity of compressed data before attempting to decompress it. This weakness creates a condition where maliciously constructed archive files can trigger invalid memory reads that ultimately lead to application crashes and denial of service conditions.
The technical exploitation of this vulnerability involves crafting a specially formatted archive file that contains malformed data structures within the compressed stream. When lrzip attempts to decompress this crafted archive using the vulnerable lzo1x_decompress function, the decompression algorithm encounters unexpected data patterns that cause it to access invalid memory locations. This invalid memory access results in segmentation faults or similar memory access violations that cause the application to terminate abruptly. The vulnerability is classified as a remote denial of service issue because an attacker can exploit it without requiring local system access, simply by providing a malicious archive file to a system running lrzip. This type of vulnerability falls under CWE-125: Out-of-bounds Read, which represents a common class of memory safety issues where programs read memory locations outside the bounds of allocated buffers.
The operational impact of CVE-2017-8845 extends beyond simple application crashes, as it can be leveraged to disrupt services that depend on lrzip for archive processing. Systems that automatically process user-uploaded archives or handle automated backup operations become particularly vulnerable to this attack vector. The vulnerability can be exploited in scenarios involving file upload systems, automated backup services, or any application that accepts compressed archives from untrusted sources. From an attacker perspective, this represents a low-effort method to cause service disruption, requiring only the creation of a malformed archive file to trigger the denial of service condition. The vulnerability demonstrates a fundamental weakness in the input validation mechanisms of the compression library, highlighting the importance of robust error handling in cryptographic and data processing functions. This issue aligns with ATT&CK technique T1499.001: Endpoint Denial of Service, which focuses on techniques that cause systems to become unavailable through resource exhaustion or application crashes.
Mitigation strategies for CVE-2017-8845 primarily involve updating to patched versions of both the LZO library and lrzip software. The vulnerability was resolved in later versions of the LZO library where proper input validation and bounds checking were implemented within the decompression routines. System administrators should ensure that all instances of lrzip are updated to versions that incorporate the patched LZO library components. Additionally, implementing proper input validation at the application level can provide defense-in-depth measures, where applications that process archives can perform preliminary checks on file integrity before invoking decompression functions. Network-level filtering and sandboxing of archive processing operations can also reduce the impact of such vulnerabilities by isolating potentially malicious archive files from critical system components. Organizations should also consider implementing automated monitoring for application crashes and unusual resource consumption patterns that might indicate exploitation attempts. The remediation process requires careful testing of updated software versions to ensure compatibility with existing workflows while addressing the security vulnerability effectively.