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

Static analysis result for SHA-256 3a21473da0a073cf…

MALICIOUS

Office (OLE) / .XLS

107.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 2b84f87f5b187ff9783ca743f6ba3491 SHA-1: 144b822a7ea9190ebd9fbccbb0f2827ebd9ff413 SHA-256: 3a21473da0a073cf47c941b85fb55e530b469a11648c27c67e5e7396ffc2ae74
100 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File

The critical heuristic firing for CVE-2009-3129 indicates that this Excel file exploits a specific vulnerability related to the FEATHEADER record. This type of exploit is commonly used to deliver malicious payloads. The OLE slack anomaly further suggests that the file has been tampered with, likely to hide malicious content.

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 109,592 bytes but its declared streams total only 24,565 bytes — 85,027 bytes (78%) 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).