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

Static analysis result for SHA-256 15b4a59aad16ba0b…

MALICIOUS

Office (OLE) / .XLS

85.9 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 914eff4cc4e34ebc7dbd557182a1d2d6 SHA-1: b51563ff06265a0694bec6e6f95b0be907d49963 SHA-256: 15b4a59aad16ba0bffd316795b6726f8735dcf644eb898dbe4369b3cf4ac533e
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The sample is a malicious Microsoft Excel file identified as exploiting CVE-2009-3129. This vulnerability allows for arbitrary code execution when the file is opened. The presence of a large slack space in the OLE structure and an x86 GetPC stub further indicate 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=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 87,946 bytes but its declared streams total only 24,565 bytes — 63,381 bytes (72%) 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).