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

Static analysis result for SHA-256 3f495fa972c5eb6e…

MALICIOUS

Office (OLE) / .XLS

133.6 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: e4a0e5a59e3da3f1677d1f6061448bb5 SHA-1: 5078bec8aadbabd944cd11dcc5d12cb1cd58c716 SHA-256: 3f495fa972c5eb6e7a4ba40cb7c7f02d0be145391a7c1083f4f7c4d06be867e9
100 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious File T1204.002 Malicious File: User Execution

The critical heuristic firing indicates exploitation of CVE-2009-3129, a known vulnerability in Microsoft Excel. This vulnerability is typically leveraged to execute arbitrary code, suggesting the file is designed to deliver a malicious payload. The OLE slack anomaly further supports the presence of unusual or injected data within the file structure.

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 136,849 bytes but its declared streams total only 24,565 bytes — 112,284 bytes (82%) 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).