CVE-2008-0888 in unzip
Summary
by MITRE
The NEEDBITS macro in the inflate_dynamic function in inflate.c for unzip can be invoked using invalid buffers, which allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via unknown vectors that trigger a free of uninitialized or previously-freed data.
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Analysis
by VulDB Data Team • 04/29/2025
The vulnerability identified as CVE-2008-0888 resides within the decompression functionality of the unzip utility, specifically within the inflate_dynamic function in the inflate.c source file. This flaw represents a critical security issue that affects the decompression process of compressed data streams. The vulnerability manifests through the NEEDBITS macro which is designed to extract bits from the input buffer during decompression operations. When this macro is invoked with invalid or malformed buffer references, it creates conditions that can lead to unpredictable system behavior.
The technical root cause of this vulnerability stems from inadequate input validation and memory management within the decompression algorithm. The NEEDBITS macro operates under assumptions about buffer integrity and data consistency that are not properly enforced when processing malformed compressed data. This weakness creates opportunities for attackers to craft specially crafted compressed files that, when processed by the vulnerable unzip utility, trigger memory corruption conditions. The flaw operates at the intersection of buffer over-read conditions and improper memory handling, creating potential pathways for both denial of service and arbitrary code execution scenarios.
From an operational perspective, this vulnerability presents significant risks to systems that process untrusted compressed data through the unzip utility. Attackers can exploit this weakness by submitting maliciously crafted archive files that, when decompressed, cause the application to access invalid memory locations or attempt to free already-released memory segments. The potential impact extends beyond simple system crashes to include possible privilege escalation and remote code execution depending on the execution context. This vulnerability affects systems running vulnerable versions of the unzip utility across multiple operating systems and platforms where this decompression library is utilized.
The security implications of CVE-2008-0888 align with CWE-125, which addresses out-of-bounds read conditions, and CWE-416, which covers use after free vulnerabilities. The attack vectors associated with this weakness can be categorized under the MITRE ATT&CK framework as privilege escalation and denial of service techniques. The vulnerability demonstrates characteristics of a heap-based buffer overflow condition where improper memory management leads to corrupted heap structures. Organizations utilizing unzip or related decompression tools should consider this vulnerability as a high-priority concern requiring immediate remediation through patching or alternative decompression mechanisms.
Mitigation strategies for this vulnerability include immediate deployment of vendor patches or updates that address the memory management issues within the inflate_dynamic function. System administrators should also implement input validation controls and restrict processing of untrusted compressed data through additional security layers. The implementation of sandboxed decompression environments and network segmentation can help limit the potential impact of exploitation attempts. Regular security assessments should include verification of decompression library versions and proper memory handling practices to prevent similar vulnerabilities from emerging in other components of the decompression stack.