CVE-2018-18521 in elfutils
Summary
by MITRE
Divide-by-zero vulnerabilities in the function arlib_add_symbols() in arlib.c in elfutils 0.174 allow remote attackers to cause a denial of service (application crash) with a crafted ELF file, as demonstrated by eu-ranlib, because a zero sh_entsize is mishandled.
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Analysis
by VulDB Data Team • 05/30/2023
The vulnerability identified as CVE-2018-18521 represents a critical divide-by-zero error within the elfutils library suite, specifically affecting the arlib_add_symbols() function in the arlib.c source file. This flaw exists in version 0.174 of the elfutils package and manifests when processing malformed ELF (Executable and Linkable Format) files that contain zero values in the sh_entsize field of section headers. The issue stems from the improper validation of input data structures that are fundamental to ELF file parsing operations, creating a condition where division operations attempt to use zero as a divisor, leading to immediate program termination.
The technical implementation of this vulnerability occurs within the context of the eu-ranlib utility, which is part of the elfutils collection used for manipulating archive files containing ELF objects. When the arlib_add_symbols() function processes a crafted ELF file, it encounters a section header where the sh_entsize field contains a value of zero. This field normally specifies the size of entries in the section, but when zero, the function performs calculations that result in division by zero, causing an arithmetic exception that terminates the application process. The flaw demonstrates poor input validation practices and lacks proper bounds checking mechanisms that should prevent invalid data from causing system crashes.
From an operational perspective, this vulnerability presents a significant denial of service risk that can be exploited remotely by attackers who can provide crafted ELF files to systems running applications that utilize the affected elfutils library. The impact extends beyond simple service disruption as it can affect any application or system component that relies on eu-ranlib or similar tools for archive processing, including build systems, packaging tools, and security scanning utilities. The vulnerability is particularly concerning in automated environments where file processing occurs without manual intervention, as it can lead to cascading failures and system instability. This type of vulnerability aligns with CWE-369, which specifically addresses the divide-by-zero weakness in software development practices.
The exploitation of this vulnerability requires minimal technical expertise and can be accomplished through the creation of specially crafted ELF files that contain malformed section headers. Attackers can leverage this weakness to disrupt services that depend on the elfutils library, potentially causing system downtime and requiring manual intervention to restore normal operations. The vulnerability affects systems across multiple platforms where elfutils is installed, making it a widespread concern for organizations maintaining build environments and software distribution pipelines. Security professionals should consider this vulnerability as part of the broader ATT&CK framework's defense evasion techniques, where adversaries may use resource exhaustion or service disruption methods to compromise system availability.
Mitigation strategies for CVE-2018-18521 should include immediate patching of affected systems with the latest elfutils releases that contain the necessary fixes for the divide-by-zero condition. Organizations should also implement proper input validation procedures and ensure that all third-party libraries are regularly updated to address known vulnerabilities. Additional protective measures include deploying automated monitoring systems that can detect unusual patterns in file processing and implementing sandboxing techniques for handling untrusted ELF files. The vulnerability highlights the importance of robust error handling and input validation in security-critical applications, particularly those handling binary file formats that are fundamental to system operations. System administrators should also consider implementing network segmentation and access controls to limit the potential impact of successful exploitation attempts.