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

Static analysis result for SHA-256 e93026613656bb81…

MALICIOUS

Office (OLE) / .XLS

120.5 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 64218a0d81bae95936a268547e561d32 SHA-1: 3c0205dfb8a645b4386d98c2952ffabe657c97c2 SHA-256: e93026613656bb81ed62823a88512219512bc84dc4158cabbc5c9e1bbf4c1897
100 Risk Score

Malware Insights

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

The sample is an Excel spreadsheet exhibiting a critical heuristic firing for CVE-2009-3129, indicating an exploit within the FEATHEADER record. Additionally, a high severity heuristic flags an OLE slack space anomaly, suggesting the presence of hidden or injected data. These indicators strongly suggest the file is designed to exploit this vulnerability upon opening, likely to download and execute a secondary payload.

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 123,399 bytes but its declared streams total only 24,565 bytes — 98,834 bytes (80%) 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).