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

Static analysis result for SHA-256 bb3e4832f0f53015…

MALICIOUS

Office (OLE) / .XLS

107.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 7dac1cd62a08d089816e69b135c13eac SHA-1: 0aefa24d1da156d446746ff2ea0ce4e1ea73056b SHA-256: bb3e4832f0f530156355e55681a78d6f382ca1bc720207a88569fa34ff7910f4
100 Risk Score

Malware Insights

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

The sample is an Excel file that triggers a critical heuristic for CVE-2009-3129, indicating an exploit for a known Excel vulnerability. The large slack space in the OLE structure is also flagged as anomalous. While no specific payload or second-stage activity was directly observed in this static analysis, the exploit itself is sufficient to classify the file as malicious. The lack of document body text or scripts means the exact nature of the exploit's payload cannot be determined.

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).