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

Static analysis result for SHA-256 4a5b6397126a1f73…

MALICIOUS

Office (OLE) / .XLS

257.5 KB Created: 1996-12-17 01:32:42 Authoring application: Microsoft Excel
MD5: 4477adb5c8e28ccbb88b19603e090768 SHA-1: fc81c8835407658548eb5db7cfae154a032ad937 SHA-256: 4a5b6397126a1f730050ea4eb9fe971c04c5c95604d9122a32c7fd23bcaeb9c9
82 Risk Score

Malware Insights

MITRE ATT&CK
T1566.002 Spearphishing Attachment T1059.005 Visual Basic T1105 Ingress Tool Transfer

The OLE document exhibits significant slack space and an appended executable payload, indicating it's a container for malicious code. Although VBA macros could not be extracted due to an unsupported format, the presence of appended executable bytes strongly suggests the file's purpose is to deliver and execute a secondary payload. The file's SHA256 hash is included as a primary IOC.

Heuristics 3

  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 263,709 bytes but its declared streams total only 24,565 bytes — 239,144 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).
  • 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.

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