CVE-2018-20673 in binutils
Summary
by MITRE
The demangle_template function in cplus-dem.c in GNU libiberty, as distributed in GNU Binutils 2.31.1, contains an integer overflow vulnerability (for "Create an array for saving the template argument values") that can trigger a heap-based buffer overflow, as demonstrated by nm.
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Analysis
by VulDB Data Team • 04/26/2020
The vulnerability identified as CVE-2018-20673 resides within the GNU libiberty library, specifically in the demangle_template function located in cplus-dem.c. This function is part of the GNU Binutils 2.31.1 distribution and serves to demangle C++ symbol names during binary analysis operations. The flaw manifests as an integer overflow condition that occurs when the function attempts to create an array for storing template argument values. This particular implementation does not properly validate the size calculations required for allocating memory resources, creating a scenario where maliciously crafted input can cause the arithmetic operations to exceed the maximum representable value for the integer data type used in the allocation process. The vulnerability is particularly concerning because it operates within a core component of the binutils suite that is widely used for system administration and software development tasks.
The technical exploitation of this integer overflow leads to a heap-based buffer overflow condition that can be triggered by the nm command, which is used to list symbols from object files. When processing specially crafted C++ symbol names containing complex template structures, the demangle_template function performs calculations that result in an overly large array allocation. The integer overflow occurs during the computation of memory requirements for template argument storage, where the calculated size becomes negative or exceeds the maximum allowable value for the data type. This overflow condition causes the subsequent memory allocation to fail or allocate insufficient memory, leading to a situation where subsequent operations write beyond the allocated buffer boundaries, potentially corrupting adjacent heap memory regions and creating opportunities for arbitrary code execution or denial of service attacks.
The operational impact of this vulnerability extends across numerous systems that rely on GNU Binutils for binary analysis and symbol resolution operations. Attackers can exploit this weakness by providing maliciously constructed C++ object files or symbol tables to applications that utilize the affected libiberty functions, including but not limited to nm, objdump, and other tools within the binutils suite. The vulnerability affects systems running GNU Binutils 2.31.1 and potentially earlier versions, making it a widespread concern for organizations that depend on these standard tools for software development, system administration, and security analysis. The exploitability of this vulnerability is enhanced by the fact that it can be triggered through normal usage patterns when processing untrusted binary input, making it particularly dangerous in environments where symbol tables from external sources are regularly analyzed.
Security mitigations for CVE-2018-20673 primarily involve upgrading to patched versions of GNU Binutils, specifically versions 2.32 and later where the integer overflow has been addressed through proper input validation and size calculation checks. System administrators should also implement defensive measures such as restricting access to binutils tools in environments where untrusted binary input is processed, employing sandboxing techniques for symbol analysis operations, and monitoring for anomalous memory allocation patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-190, which specifically addresses integer overflow conditions, and can be categorized under ATT&CK technique T1059.007 for the execution of malicious code through binary manipulation. Organizations should also consider implementing memory safety checks and address space layout randomization to reduce the effectiveness of potential exploitation attempts, while maintaining regular updates to ensure protection against similar vulnerabilities in the broader software supply chain.