SANS researcher shares DWG VBA detection rule
Didier Stevens published a YARA rule to detect orphaned VBA projects hidden inside AutoCAD DWG files, finding two matching samples via VirusTotal.
Sourceisc.sans.edu — open the original
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In this short SANS Internet Storm Center diary, handler Didier Stevens shares a YARA rule designed to detect 'orphaned VBA projects' embedded inside AutoCAD DWG files. The technique leverages the fact that DWG files can contain an OLE2/Compound File Binary Format structure (signature D0 CF 11 E0 A1 B1 1A E1) with VBA project artifacts, such as a '[Host Extender Info]' section, that are not normally expected in legitimate DWG files — an indicator that malicious or anomalous macro content may have been embedded.
Stevens ran the YARA rule as a VirusTotal retrohunt and found only two matching files, identified by SHA256 hash. The diary does not provide further analysis of these samples, confirm active exploitation, or describe a specific campaign — it is a detection-engineering note intended to help analysts and threat hunters identify this file structure pattern in their own environments or via VirusTotal hunting.
For defenders, the actionable takeaway is the YARA rule itself, which can be deployed in file-scanning pipelines, EDR, or VirusTotal retrohunts to flag DWG files that may carry embedded VBA macro artifacts — a potential technique for delivering malicious code via CAD file formats, an unusual but plausible initial-access vector in engineering, architecture, or manufacturing environments where DWG files are routinely exchanged.
Source reporting: https://isc.sans.edu/diary/rss/33434
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