CVE-2016-2091 in libdwarf
Summary
by MITRE
The dwarf_read_cie_fde_prefix function in dwarf_frame2.c in libdwarf 20151114 allows attackers to cause a denial of service (out-of-bounds read) via a crafted ELF object file.
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Analysis
by VulDB Data Team • 07/07/2022
The vulnerability identified as CVE-2016-2091 represents a critical out-of-bounds read flaw within the libdwarf library version 20151114, specifically within the dwarf_read_cie_fde_prefix function located in the dwarf_frame2.c file. This library serves as a fundamental component for processing dwarf debugging information in elf object files, making it a critical element in software development and debugging toolchains. The flaw manifests when the library processes malformed or crafted elf object files that contain specially constructed dwarf frame information, creating a scenario where memory access occurs beyond the allocated bounds of the target buffer.
The technical implementation of this vulnerability stems from insufficient input validation and boundary checking within the dwarf frame parsing logic. When the dwarf_read_cie_fde_prefix function encounters a crafted elf file, it fails to properly validate the length fields or structure boundaries of the dwarf frame information records. This allows an attacker to manipulate the parsing process by inserting malicious data that causes the function to read memory locations beyond the intended buffer boundaries. The vulnerability operates at the level of the dwarf debugging information format, which is used extensively in linux systems for stack unwinding, debugging, and crash analysis. The out-of-bounds read can potentially expose sensitive memory contents or cause the application to crash, resulting in a denial of service condition that affects any software relying on libdwarf for processing elf files.
From an operational impact perspective, this vulnerability creates significant risks for systems that process untrusted elf object files, including software development tools, debugging utilities, and security analysis frameworks. The attack vector is particularly concerning because it requires only the presence of a malicious elf file in a processing pipeline rather than complex exploitation techniques. The vulnerability affects the broader ecosystem of software development and security tools that depend on libdwarf, potentially compromising the integrity of debugging processes and crash analysis systems. This flaw can be exploited in contexts such as automated build systems, vulnerability scanners, or any application that parses elf files without proper input sanitization. The impact extends beyond simple denial of service, as the out-of-bounds memory access could potentially reveal sensitive information about system memory layout or application state, making it a potential precursor to more sophisticated attacks.
The mitigation strategy for CVE-2016-2091 involves immediate patching of the libdwarf library to version 20160501 or later, which contains the necessary fixes for the boundary checking issues in the dwarf_read_cie_fde_prefix function. System administrators and developers should also implement input validation measures when processing elf files, including verifying file integrity and implementing sandboxing techniques for untrusted input. The vulnerability aligns with CWE-129, which addresses insufficient validation of length fields, and can be categorized under ATT&CK technique T1059 for execution through malicious file processing. Organizations should also consider implementing automated vulnerability scanning tools that can detect the presence of vulnerable libdwarf versions in their software dependencies. Additional defensive measures include regular security updates for development toolchains and maintaining awareness of the broader attack surface that includes debugging and analysis tools that may be vulnerable to similar out-of-bounds read conditions.