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

Static analysis result for SHA-256 18ac05182ad2e770…

MALICIOUS

Office (OLE) / .XLS

78.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: fd392526c11267b24cc5b226074f8e84 SHA-1: 51831c2e632914b7b94506ca7924a0877c5f6074 SHA-256: 18ac05182ad2e770495890cc51e708b08ab1c56958f7ebee02a21639b45243ad
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The file is a malicious Microsoft Excel spreadsheet that exploits CVE-2009-3129, a known vulnerability in Excel's FEATHEADER record. This exploit allows for arbitrary code execution, likely to download and run a secondary payload. The OLE structure also contains an appended executable payload, further indicating malicious intent.

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 79,915 bytes but its declared streams total only 24,565 bytes — 55,350 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).
  • 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.