CVE-2017-7300 in binutils
Summary
by MITRE
The Binary File Descriptor (BFD) library (aka libbfd), as distributed in GNU Binutils 2.28, has an aout_link_add_symbols function in bfd/aoutx.h that is vulnerable to a heap-based buffer over-read (off-by-one) because of an incomplete check for invalid string offsets while loading symbols, leading to a GNU linker (ld) program crash.
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Analysis
by VulDB Data Team • 12/04/2024
The vulnerability identified as CVE-2017-7300 resides within the Binary File Descriptor library, commonly known as BFD, which is a core component of the GNU Binutils suite. This library serves as a fundamental interface for handling various binary file formats, enabling tools like the GNU linker to process and manipulate object files. The specific flaw manifests in the aout_link_add_symbols function located in bfd/aoutx.h, which is responsible for managing symbol loading within a.out format binaries. This vulnerability represents a critical heap-based buffer over-read condition that occurs due to inadequate validation of string offsets during symbol processing operations.
The technical implementation of this vulnerability stems from an incomplete boundary check that fails to properly validate string offset values when processing symbol tables within binary files. When the GNU linker attempts to load symbols from an a.out format file, it iterates through symbol entries and processes string offsets that reference symbol names within the binary. The flaw occurs when an invalid or malformed string offset is encountered, causing the function to read beyond the allocated heap buffer boundaries by exactly one byte, hence the classification as an off-by-one error. This specific memory access violation occurs because the validation logic does not adequately verify that the calculated string offset remains within the bounds of the allocated memory region, allowing for unauthorized memory access patterns that can result in unpredictable behavior.
The operational impact of this vulnerability is significant as it can cause the GNU linker program to crash or terminate unexpectedly when processing maliciously crafted binary files. This denial-of-service condition affects developers and system administrators who rely on the GNU toolchain for building software, particularly in automated build environments where continuous integration systems may be compromised by this vulnerability. The crash occurs during the symbol loading phase of the linking process, which means that legitimate compilation workflows can be interrupted, potentially causing extended development delays and system unavailability. The vulnerability is particularly concerning in environments where automated build systems process untrusted binary inputs, as it can be exploited to cause system instability and potentially serve as a precursor to more sophisticated attacks targeting the broader GNU toolchain ecosystem.
Mitigation strategies for CVE-2017-7300 primarily involve upgrading to patched versions of GNU Binutils where the validation logic has been corrected to properly check string offset boundaries before processing symbol data. System administrators should implement immediate patch management procedures to update all affected systems running GNU Binutils 2.28 or earlier versions. Additional defensive measures include implementing strict input validation for binary files processed by the linker, particularly those from untrusted sources, and monitoring for unusual linker behavior or crash patterns that may indicate exploitation attempts. The vulnerability aligns with CWE-125, which describes out-of-bounds read conditions, and could potentially be leveraged in broader attack chains targeting the software supply chain as outlined in ATT&CK technique T1588.3 for tool development and T1078 for valid accounts, since compromised build systems could be used to distribute malicious binaries through legitimate toolchain channels. Organizations should also consider implementing sandboxing mechanisms for binary processing and maintaining comprehensive system monitoring to detect anomalous behavior that might indicate exploitation attempts.