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

Static analysis result for SHA-256 81c47ec5289dca13…

MALICIOUS

Office (OLE) / .XLS

105.9 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 9f814bc280be224d97abb18b12fc1797 SHA-1: da9aa6a53317a721e6e977725f43a90571c45c21 SHA-256: 81c47ec5289dca13e84946bb78076a01efc45f35287306b2a8308d2e0be7e455
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The critical heuristic firing indicates the sample exploits CVE-2009-3129, a known vulnerability in Microsoft Excel. This vulnerability allows for arbitrary code execution when the malicious Excel file is opened. No document body or scripts were extracted, but the exploit itself is sufficient to classify the attack pattern.

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 108,426 bytes but its declared streams total only 24,565 bytes — 83,861 bytes (77%) 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).