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

Static analysis result for SHA-256 6bce5048cc4f12d8…

MALICIOUS

Office (OLE) / .XLS

77.9 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 2621134a73da1a7c448d7832fd263b1a SHA-1: ef81a204a8404174b123e83b620030930f7c553f SHA-256: 6bce5048cc4f12d865da880870481ea6aa3c5a44f21b46e838c0d4bc33b9afb5
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 on the victim's machine. No further payload or network activity was observed in this static analysis.

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 79,754 bytes but its declared streams total only 24,565 bytes — 55,189 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).