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

Static analysis result for SHA-256 5c9d3924c91b456e…

MALICIOUS

Office (OLE) / .XLS

2.10 MB
MD5: 44a5df65319183fcd2054699d2d67e3a SHA-1: 27d10215b47ba5c61345df3e518d65ff67d0c4c3 SHA-256: 5c9d3924c91b456e1e339ae80ce27d2ca2743bb7af5d6a4cdf5eafa35a55ad98
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The file is a malicious Microsoft Excel spreadsheet that leverages the CVE-2009-3129 vulnerability. This vulnerability allows for arbitrary code execution by exploiting a FEATHEADER record overflow within the workbook stream. The presence of an appended executable-looking payload and significant slack space further indicates malicious intent, likely for delivering a secondary stage.

Heuristics 4

  • 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.
  • PEB access via FS segment (x86) high SC_PEB_ACCESS
    PEB access via FS segment (x86)
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 2,206,208 bytes but its declared streams total only 20,469 bytes — 2,185,739 bytes (99%) 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.