CVE-2020-24823 in Libelfin
Summary
by MITRE • 08/04/2021
A vulnerability in the dwarf::to_string function of Libelfin v0.3 allows attackers to cause a denial of service (DOS) through a segmentation fault via a crafted ELF file.
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Analysis
by VulDB Data Team • 08/08/2021
The vulnerability identified as CVE-2020-24823 resides within the libelfin library version 0.3, specifically within the dwarf::to_string function implementation. This flaw represents a classic buffer overread condition that manifests when processing malformed ELF files containing crafted DWARF debugging information. The issue occurs during the parsing of debug data structures where the function fails to properly validate input boundaries before attempting to read memory locations. When an attacker constructs an ELF file with malformed DWARF sections that exceed expected buffer limits, the dwarf::to_string function attempts to access memory beyond allocated boundaries, resulting in a segmentation fault and subsequent process termination.
From a technical perspective, this vulnerability operates at the intersection of binary analysis and memory safety, aligning with CWE-129, which addresses improper validation of array indices, and CWE-125, which covers out-of-bounds read conditions. The flaw demonstrates characteristics consistent with the ATT&CK technique T1203, where adversaries leverage software vulnerabilities to gain system access or cause service disruption. The root cause stems from insufficient input validation mechanisms within the DWARF parsing logic, where the library assumes valid data structures without proper bounds checking. This particular implementation flaw affects any application that utilizes libelfin for ELF file analysis, particularly those processing untrusted binary content.
The operational impact of CVE-2020-24823 extends beyond simple service disruption, as it can be exploited to cause denial of service across multiple system components that depend on libelfin for binary analysis. Systems utilizing this library for debugging, reverse engineering, or security analysis tools become vulnerable to crafted ELF file attacks that can terminate processes or cause application crashes. The vulnerability is particularly concerning in environments where automated binary analysis systems process unknown or untrusted files, as a single malicious ELF file can bring down entire analysis pipelines. Attackers can leverage this weakness to disrupt services, create persistent denial of service conditions, or potentially use it as a stepping stone for more sophisticated attacks targeting the broader system infrastructure.
Mitigation strategies for CVE-2020-24823 should focus on immediate library updates to versions that address the buffer overread condition, typically through implementation of proper bounds checking and input validation. Organizations should also implement defensive measures such as sandboxing binary analysis processes and employing strict input validation for all ELF file processing. Network-level protections can include implementing file type validation and content filtering to prevent malicious ELF files from reaching systems that utilize libelfin. Additionally, system administrators should monitor for unusual process termination patterns and implement robust logging mechanisms to detect exploitation attempts. The fix typically involves adding proper boundary checks within the dwarf::to_string function to validate array indices against allocated buffer sizes, ensuring that memory access operations remain within safe limits. Organizations should also consider implementing alternative binary analysis approaches that do not rely on vulnerable library versions, particularly in high-security environments where denial of service attacks could have critical operational consequences.