CVE-2015-8538 in libdwarf
Summary
by MITRE
dwarf_leb.c in libdwarf allows attackers to cause a denial of service (SIGSEGV).
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Analysis
by VulDB Data Team • 10/14/2019
The vulnerability identified as CVE-2015-8538 resides within the dwarf_leb.c component of the libdwarf library, a critical piece of software used for parsing and processing debug information in binary files. This library serves as the foundation for numerous debugging and analysis tools across various operating systems and development environments, making its security paramount to overall system integrity. The flaw manifests as a denial of service condition that can be triggered by maliciously crafted input data, specifically through malformed LEB128 encoded values within debug information sections of binary files.
The technical implementation of this vulnerability stems from insufficient input validation within the libdwarf library's handling of Little Endian Base 128 (LEB128) encoded data structures. LEB128 is a variable-length encoding scheme commonly used in debug information formats such as DWARF to represent integers efficiently. When the library processes malformed LEB128 sequences, particularly those that exceed expected bounds or contain invalid continuation byte patterns, the parsing routine fails to properly validate the input before attempting to access memory locations. This lack of proper boundary checking leads to memory access violations that result in segmentation faults and subsequent process termination.
The operational impact of CVE-2015-8538 extends beyond simple service disruption as it affects the reliability of debugging and analysis tools that depend on libdwarf. Attackers can exploit this vulnerability by crafting malicious binary files containing malformed debug information, which when processed by vulnerable applications such as debuggers, profilers, or static analysis tools, will cause those applications to crash. This creates a significant risk for developers and system administrators who rely on these tools for software development, security analysis, and system troubleshooting. The vulnerability is particularly concerning because it can be triggered through legitimate file processing workflows, making it difficult to detect and prevent through traditional input filtering mechanisms.
From a cybersecurity perspective, this vulnerability maps to CWE-129: Improper Validation of Array Index and CWE-787: Out-of-bounds Write, as it involves improper validation of input data that leads to memory access violations. The attack pattern aligns with ATT&CK technique T1499.004: Endpoint Denial of Service, where adversaries target system resources to disrupt availability of services. The vulnerability demonstrates how seemingly benign parsing operations can become attack vectors when proper input validation is absent. Organizations using affected versions of libdwarf should immediately implement patches or workarounds to prevent exploitation, as the impact extends to any system where debug information processing occurs, including development environments, security analysis platforms, and automated build systems that utilize these libraries for code analysis and debugging purposes.