CVE-2023-38657

What it actually does

Out-of-bounds write in LXT2 zlib block decompression allows arbitrary code execution when processing a malformed file.

Why it matters to the business

Compromise of analyst workstations running the affected tool can result in data theft, lateral movement, or ransomware deployment when users open malicious waveform files.

How an attack unfolds

An attacker crafts a .lxt2 file containing a malformed zlib block that triggers the out-of-bounds write. The file is delivered via email, download, or shared storage; the victim opens it in the vulnerable application, causing the flaw to execute attacker-controlled code.

How to fix it

Upgrade to a patched GTKWave release when available; until then, disable LXT2 support or replace the tool with an unaffected waveform viewer. Do not open .lxt2 files from untrusted sources.

How to confirm the fix worked

Confirm the installed GTKWave version against vendor advisories, attempt to open known-good .lxt2 files, and verify that no crash or unexpected behavior occurs with test cases exercising zlib blocks.

Typical attack path

1. Craft .lxt2 file with oversized or malformed zlib data targeting the decompression routine
2. Deliver the file to the victim through common channels
3. Victim opens the file using the vulnerable GTKWave version
4. Out-of-bounds write occurs during parsing, leading to code execution

How to detect it

Review system and application logs for GTKWave crashes or child process spawns immediately after .lxt2 file access; correlate with file-creation timestamps and user activity on engineering workstations.

What your security team should do

• Block or sandbox opening of .lxt2 files from external sources
• Replace GTKWave with a maintained alternative on analyst systems
• Add file-type restrictions and user training to prevent accidental opening of untrusted waveform files
• Monitor application crash reports for GTKWave related to LXT2 parsing