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

Static analysis result for SHA-256 35b483a6830ed8bd…

MALICIOUS

Office (OLE) / .XLS

107.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: ea9d2526b9a1a9d0d04a7069d56510b1 SHA-1: affee425f8de7513e47eff4c26312de343e7f4b2 SHA-256: 35b483a6830ed8bd1ccc413b689ce5a2cfde4c2cc1f238ab1749712b4f1cac11
100 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File

The critical heuristic firing indicates exploitation of CVE-2009-3129, a known vulnerability in Microsoft Excel. The OLE slack anomaly further suggests the presence of embedded malicious content. While no document body or scripts were extracted, the exploit itself is sufficient to classify this as a malicious document designed to compromise the user's system.

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=22, isf=4, cbHdrData=4). 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 109,592 bytes but its declared streams total only 24,565 bytes — 85,027 bytes (78%) 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).