Win.Trojan.Since-1 — Office (OLE) malware analysis

Static analysis result for SHA-256 d5a88f14d163bdf9…

MALICIOUS

Office (OLE)

23.5 KB Created: 1993-09-28 15:08:00 Authoring application: Microsoft Word for Windows 95 First seen: 2012-06-14
MD5: eaf1465b171e7086d4a4f8b4a91b7c52 SHA-1: 5377d6865a31451c2fe14f3679c04668c18b5967 SHA-256: d5a88f14d163bdf97a5b5442de349cb2d62c380fb364c519bf626a9a9189769e
260 Risk Score

Malware Insights

Win.Trojan.Since-1 · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic

The file exhibits characteristics of legacy malware, specifically the presence of WordBasic auto-execution markers ('autoopen') and suspicious OLE structure anomalies. ClamAV detections confirm its malicious nature, identifying it as Win.Trojan.Since-1. The embedded OLE object is a primary indicator of the malicious payload.

Heuristics 5

  • ClamAV: Win.Trojan.Since-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Trojan.Since-1
  • Embedded Office document has suspicious static findings critical EMBEDDED_OFFICE_CHILD_STATIC_TRIAGE
    A CFB/OLE Office document was found inside another file type and its carved contents matched Office exploit or payload heuristics. This catches wrapped exploit documents where the top-level file routes to a PE, archive, or generic scanner instead of Office.
  • OLE document has large unaccounted-for region high OLE_SLACK_ANOMALY
    OLE file is 18,792 bytes but its declared streams total only 0 bytes — 18,792 bytes (100%) 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).
  • Legacy WordBasic auto-exec macro marker medium OLE_LEGACY_WORDBASIC_AUTOEXEC
    OLE Word document contains a legacy WordBasic auto-execution marker such as AutoOpen, but no modern VBA project was recovered and no stronger macro-virus family marker was present. This is analyst-facing evidence for old Word macro execution surface, not a downloader or parser-CVE attribution by itself.
  • CFB header with no readable streams medium OLE_PARSE_EMPTY_STREAMS
    The file begins with a valid OLE2/CFB header but exposes no directory streams. A non-empty compound document with an unreadable directory is anomalous — it is seen with truncated/corrupt files and, more importantly, with content deliberately shifted off byte boundaries to defeat parsers while the host application still recovers the object.

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
embedded_office_off00001498.ole embedded-office Embedded OLE/CFB Office body inside ole container at offset 0x1498 18792 bytes
SHA-256: 173e27ae54b3d59c26047610489b86f38784cd997a502caf894a3dd3de052df9
Detection
ClamAV: Win.Trojan.Since-1
Obfuscation or payload: unlikely

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