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

Static analysis result for SHA-256 3cecbaa5194d4951…

MALICIOUS

Office (OLE) / .XLS

54.6 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 7e9e21fbb8e156dc393b8c8af7f891ae SHA-1: bfd10ee4c321e964d7ba2b2ce4ca8c61673b8ec0 SHA-256: 3cecbaa5194d49514df6c497ddd335823aa08cc989a578ed119d79512bcc21a3
100 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1204.002 Malicious File: User Execution

The sample is an Excel spreadsheet that triggers the CVE-2009-3129 vulnerability due to a FEATHEADER record overflow. This indicates the file is designed to exploit this specific Excel flaw, likely to execute arbitrary code. The large slack space in the OLE structure is also anomalous and may be used to hide malicious content.

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 55,870 bytes but its declared streams total only 24,565 bytes — 31,305 bytes (56%) 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).