Malicious Office (OLE) / .UNO — malware analysis report

Static analysis result for SHA-256 c23f7cc00214db9c…

MALICIOUS

Office (OLE) / .UNO

40.2 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel First seen: 2026-05-10
MD5: 3f29f479466eb88c2dd59ea081f4aaae SHA-1: bb86c9441753e3148cd6a590e996cea3c2d02f6c SHA-256: c23f7cc00214db9cd18f9ff7b65d921509793c887da4e47b0cf9cc2f0cb0a07b
100 Risk Score

Malware Insights

The file is an Excel OLE document with a significant amount of slack space, which is a common characteristic of malicious documents. Although VBA macros could not be extracted due to an unsupported format, the document body contains text resembling application forms for permits. This content suggests a phishing or social engineering attack, aiming to trick users into submitting personal information. The lack of extractable scripts and specific IOCs limits the confidence in a more precise assessment.

Heuristics 2

  • Excel Index Array exploit — CVE-2008-3005 critical CVE likely CVE_2008_3005
    Legacy Excel workbook has the CVE-2008-3005 exploit shape: a compact BIFF8 FORMAT-index cluster paired with a normal XF table and a large unallocated OLE slack region used to stage the payload. The FORMAT pattern alone is not sufficient, so the rule requires the OLE slack payload-hiding context to keep false positives low.
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 41,201 bytes but its declared streams total only 21,308 bytes — 19,893 bytes (48%) live in unallocated sector slack. This is the canonical hiding place for pre-macro-era Office exploit payloads (XOR-encoded shellcode reached via a parser pointer-corruption bug in the document structure).