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

Static analysis result for SHA-256 1a5ff703bf13085a…

MALICIOUS

Office (OLE) / .XLS

59.1 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: ce7251c84f256261ffa639337c0ac210 SHA-1: a5034cf50cbf7edb120fe607924cbc7b845d52ce SHA-256: 1a5ff703bf13085a4785cbd8aed8d02942b4927817c20071476c4efbd43a51bd
140 Risk Score

Malware Insights

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

The critical heuristic firing for CVE-2009-3129 indicates that this Excel file contains a record overflow vulnerability. This, combined with the high heuristic for WinExec, strongly suggests the file is designed to exploit this vulnerability to execute arbitrary code. The large slack space in the OLE document is also a common characteristic of malicious Office documents.

Heuristics 3

  • 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.
  • Reference to WinExec API high SC_STR_WINEXEC
    Reference to WinExec API
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 60,554 bytes but its declared streams total only 24,565 bytes — 35,989 bytes (59%) 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).