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

Static analysis result for SHA-256 099c4f801a70fcf7…

MALICIOUS

Office (OLE) / .XLS

115.1 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 0cc374bf04ec5ab206a4a0d2bec4d85a SHA-1: 170f273990deb52a5809477b8eea64be86c21bba SHA-256: 099c4f801a70fcf74ba853b62af62133b708b890f03a60071b63ad5887d0f903
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The file is identified as malicious due to multiple high-severity heuristics indicating an OLE document with appended payload bytes and an anomaly in its slack space. Specifically, the CVE-2009-3129 heuristic points to an Excel FEATHEADER record overflow vulnerability, which is a known method for achieving arbitrary code execution.

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.
  • x86 GetPC stub (CALL $+5; POP EDI) high SC_GETPC_CALL
    x86 GetPC stub (CALL $+5; POP EDI)
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 117,903 bytes but its declared streams total only 24,565 bytes — 93,338 bytes (79%) 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.