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

Static analysis result for SHA-256 35961e75fc57f0fd…

MALICIOUS

Office (OLE) / .XLS

270.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: dd7d8c67d391c837c2d63b10d50a9829 SHA-1: 090d77c3c05ec2c9e7eae928c040f8add6d04c6e SHA-256: 35961e75fc57f0fde94960e5e0e50e9c396130169d2e0487a570a37d074a5063
100 Risk Score

Malware Insights

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

The critical heuristic firing indicates exploitation of CVE-2009-3129, a known vulnerability in Microsoft Excel. The OLE slack anomaly further suggests the file has been tampered with to include malicious content. While no specific family is identified, the exploit indicates a malicious intent to compromise the user's system upon opening the spreadsheet.

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 276,494 bytes but its declared streams total only 24,565 bytes — 251,929 bytes (91%) 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).