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

Static analysis result for SHA-256 5ccc68c1f330c4d7…

MALICIOUS

Office (OLE) / .XLS

107.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: bfe6713bbc20581d23d250512f0a22b0 SHA-1: 22ff92087460fbcbd03b1e6ff72835f7705a3739 SHA-256: 5ccc68c1f330c4d7fa0f806000757ce506675c99b524e4721dc804cf7e28e0a5
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The file is an Excel spreadsheet exhibiting an OLE slack anomaly and an appended payload, indicating it is likely a malicious document. Critical heuristic firings confirm exploitation of CVE-2009-3129, a known vulnerability in Excel's FEATHEADER record, which allows for arbitrary code execution.

Heuristics 3

  • 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).
  • OLE file has appended executable-looking payload bytes high OLE_APPENDED_PAYLOAD
    OLE compound file contains a large high-entropy region beyond the declared major streams and that region includes shellcode, PE, or loader API markers. This is a payload-carrier signal, not a specific CVE attribution by itself.