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

Static analysis result for SHA-256 688eb051fd87ad69…

MALICIOUS

Office (OLE) / .XLS

84.8 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 790b4a2c03086bd1917433a5084d2068 SHA-1: db786042f99a8418dcc793df41642b2fdd496509 SHA-256: 688eb051fd87ad69fa2e7f7160ee3f5a2cdd530c4c60f487cda7d40edebceb75
140 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The file is a Microsoft Excel document that contains a critical heuristic indicating exploitation of CVE-2009-3129. This vulnerability allows for arbitrary code execution within Excel. 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 86,804 bytes but its declared streams total only 24,565 bytes — 62,239 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).