CVE-2007-0619 in chmlib
Summary
by MITRE
chmlib before 0.39 allows user-assisted remote attackers to execute arbitrary code via a crafted page block length in a CHM file, which triggers memory corruption.
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Analysis
by VulDB Data Team • 07/16/2019
The vulnerability identified as CVE-2007-0619 affects chmlib versions prior to 0.39 and represents a critical memory corruption flaw that enables remote code execution through maliciously crafted CHM files. This vulnerability resides in the handling of page block length parameters within CHM (Compiled HTML Help) file structures, where improper input validation allows attackers to manipulate memory layout and potentially execute arbitrary code on vulnerable systems. The issue specifically manifests when the chmlib library processes malformed CHM files containing crafted page block length values that exceed expected boundaries, leading to buffer overflows and memory corruption conditions that can be exploited by remote attackers.
The technical implementation of this vulnerability stems from insufficient bounds checking within the CHM file parsing logic of chmlib. When processing CHM files, the library reads page block length values without adequate validation to ensure they remain within acceptable memory allocation limits. This flaw creates a condition where attackers can craft CHM files with oversized page block length parameters that cause the library to allocate insufficient memory buffers, subsequently leading to memory corruption when the library attempts to write data beyond allocated boundaries. The vulnerability operates at the memory management level and can be triggered during normal CHM file processing operations, making it particularly dangerous as it requires no special privileges from the attacker beyond the ability to deliver a malicious CHM file to a victim system.
The operational impact of CVE-2007-0619 extends across numerous systems that rely on chmlib for CHM file processing, including web browsers, help system viewers, and document processing applications. Attackers can leverage this vulnerability through user-assisted remote execution scenarios where victims unknowingly open or process maliciously crafted CHM files, potentially through email attachments, web downloads, or shared network resources. The memory corruption resulting from this vulnerability can lead to system crashes, data corruption, or more critically, full system compromise through remote code execution. This vulnerability particularly affects systems running older versions of chmlib and applications that depend on it for CHM file handling, making it a significant concern for organizations maintaining legacy systems or those with outdated software components.
Mitigation strategies for CVE-2007-0619 primarily focus on upgrading to chmlib version 0.39 or later, which includes proper bounds checking and memory validation mechanisms. Organizations should conduct comprehensive inventory assessments to identify all systems utilizing vulnerable versions of chmlib and prioritize patching efforts accordingly. Additionally, implementing network-based controls such as web application firewalls and content filtering solutions can help prevent the delivery of malicious CHM files to user systems. Security teams should also consider deploying runtime protections and memory integrity checks to detect and prevent exploitation attempts. From a compliance perspective, this vulnerability aligns with CWE-121, which addresses stack-based buffer overflow conditions, and can be mapped to ATT&CK technique T1203, representing exploitation of software vulnerabilities through memory corruption attacks. The vulnerability demonstrates the critical importance of proper input validation and memory management practices in preventing remote code execution scenarios, particularly in libraries that process untrusted binary data formats.