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

Static analysis result for SHA-256 3bb3c03838b820b2…

MALICIOUS

Office (OLE) / .XLS

78.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel First seen: 2026-05-11
MD5: c9eff402962d785ec48019c2a5dda3fd SHA-1: 322b369b6dc5bfc32c5c852ec10022bf10782e46 SHA-256: 3bb3c03838b820b2758077cb2557c284d60fd7fcce104ff45a71bb7c92d63e5e
100 Risk Score

Heuristics 2

  • CVE-2009-3129 — Excel FEATHEADER record overflow critical CVE exact CVE_2009_3129
    Workbook BIFF stream contains a FEATHEADER (Feature Header) record with anomalous size (record_size=23, isf=2, cbHdrData=4294967295). Legitimate FEATHEADER records are tiny (<100 bytes) and carry cbHdrData values that fit in the record body; the value here is the documented CVE-2009-3129 exploit primitive — cbHdrData drives a memcpy with attacker-controlled size, leading to memory corruption and code execution in Excel 2007/2003.
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 79,822 bytes but its declared streams total only 24,565 bytes — 55,257 bytes (69%) 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).