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

Static analysis result for SHA-256 a10b56c4cbeb267d…

MALICIOUS

Office (OLE) / .XLS

107.0 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: ed05be43b4662f772e3796a8d266fd12 SHA-1: 553f454c4ed0c9df246c40ff3efbd4af6bf7748d SHA-256: a10b56c4cbeb267d8568752e25e4340a0d3d11b89d50c7841419a35a43237a2a
82 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic

The OLE file exhibits significant slack space and an appended executable-looking payload, indicating a potential attempt to hide malicious content. The 'OFFICE_FORMAT_UNSUPPORTED' heuristic suggests that VBA macros could not be extracted, but the presence of appended payload bytes strongly suggests this is a malicious OLE file designed to deliver a secondary payload. The exact nature of the payload and delivery mechanism remains unclear due to the inability to extract VBA macros.

Heuristics 3

  • 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).
  • OLE file has appended executable-looking payload bytes high OLE_APPENDED_PAYLOAD
    OLE compound file contains a large high-entropy region beyond the declared major streams and that region includes shellcode, PE, or loader API markers. This is a payload-carrier signal, not a specific CVE attribution by itself.
  • Unsupported Office format for VBA extraction info OFFICE_FORMAT_UNSUPPORTED
    olevba could not extract VBA macros (PermissionError); format-agnostic byte-level scans still ran. Likely legacy, encrypted, or malformed OLE/OOXML — re-scanning the same bytes will yield the same outcome.