CVE-2023-35702 in GTKWave
Summary
by MITRE • 01/08/2024
Multiple stack-based buffer overflow vulnerabilities exist in the FST LEB128 varint functionality of GTKWave 3.3.115. A specially crafted .fst file can lead to arbitrary code execution. A victim would need to open a malicious file to trigger these vulnerabilities.This vulnerability concerns the fstReaderVarint32 function.
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Analysis
by VulDB Data Team • 01/08/2024
The vulnerability identified as CVE-2023-35702 represents a critical stack-based buffer overflow affecting GTKWave version 3.3.115, specifically within its FST LEB128 varint parsing functionality. This issue manifests in the fstReaderVarint32 function which processes variable-length integer values from FST (Fast Signal Trace) files, a common format for storing waveform data in electronic design automation tools. The flaw occurs when the application processes malformed FST files containing specially crafted varint sequences that exceed the allocated stack buffer boundaries, creating conditions ripe for arbitrary code execution.
The technical exploitation of this vulnerability stems from inadequate input validation within the FST file parser's handling of LEB128 (Little Endian Base 128) encoded variable integers. LEB128 is a variable-length encoding scheme commonly used in binary formats to represent integers efficiently, where each byte contains 7 bits of data and a continuation bit indicating if more bytes follow. In GTKWave's implementation, the fstReaderVarint32 function fails to properly validate the length of incoming LEB128 sequences, allowing malicious actors to craft FST files with oversized varint encodings that overflow the fixed-size stack buffer allocated for parsing these values. This type of vulnerability maps directly to CWE-121 Stack-based Buffer Overflow, which occurs when a program writes data beyond the boundaries of a stack-allocated buffer.
The operational impact of this vulnerability extends beyond simple code execution, as it provides attackers with a potential path to full system compromise through the exploitation of a widely-used waveform viewing tool in electronic design automation environments. When a user opens a maliciously crafted FST file within GTKWave, the application's failure to validate input data leads to stack corruption that can be leveraged to execute arbitrary code with the privileges of the compromised user. This attack vector is particularly concerning in professional electronic design automation workflows where engineers frequently open and analyze waveform data from various sources, making the attack surface more expansive than typical software vulnerabilities.
Security professionals should consider this vulnerability in the context of the ATT&CK framework's technique T1203, which involves exploitation of software vulnerabilities for privilege escalation and code execution. The vulnerability's exploitation requires user interaction through opening a malicious file, aligning with T1204.002, which covers user execution of malicious files. Mitigation strategies should include immediate patching of GTKWave to version 3.3.116 or later, which contains the necessary fixes for the buffer overflow in fstReaderVarint32. Additionally, implementing file validation mechanisms and restricting file access to trusted sources can provide defense-in-depth measures against potential exploitation attempts. Organizations utilizing GTKWave in their design automation workflows should also consider implementing sandboxing techniques for FST file processing and monitoring for unusual file access patterns that might indicate exploitation attempts.