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

Static analysis result for SHA-256 cea4a79b3b2bb9c0…

MALICIOUS

Office (OLE) / .XLS

205.6 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: ece553242f9abb9e5ed5607ba884cdb2 SHA-1: 80d434bcd839fe4f9740ae326cd4da798394dc94 SHA-256: cea4a79b3b2bb9c0f592f7129cd52d4c3ecbe662f795d5760ec66504a7d7dca9
100 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File

The critical heuristic firing indicates exploitation of CVE-2009-3129, a known vulnerability in Microsoft Excel. This suggests the file is designed to exploit this flaw upon opening. The large amount of slack space in the OLE document is also a suspicious indicator. No document body or scripts were extracted, but the exploit itself is sufficient to classify the file as malicious.

Heuristics 2

  • 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=22, isf=4, cbHdrData=4). 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.
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 210,583 bytes but its declared streams total only 24,565 bytes — 186,018 bytes (88%) 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).