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

Static analysis result for SHA-256 7045a743b7f145b3…

MALICIOUS

Office (OLE)

24.0 KB Created: 1993-09-28 15:08:00 Authoring application: Microsoft Word for Windows 95 First seen: 2012-06-14
MD5: 850d080acc0ce9a25891dee9ae616888 SHA-1: 9e1c0343a562a49da664cd75a2bfb52b13652273 SHA-256: 7045a743b7f145b3a9643269e235be695d8f8fc05ce3f1d1d052a538c32ac257
260 Risk Score

Malware Insights

Win.Trojan.Silvina-1 · confidence 95%

MITRE ATT&CK
T1059.005 Visual Basic

The presence of legacy WordBasic auto-exec markers like 'AutoOpen' and critical heuristics related to embedded OLE objects strongly indicate malicious intent. ClamAV detections confirm this, identifying the sample as Win.Trojan.Silvina-1. The embedded OLE object is the primary indicator of a potential secondary payload or exploit.

Heuristics 5

  • ClamAV: Win.Trojan.Silvina-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Trojan.Silvina-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 19,438 bytes but its declared streams total only 0 bytes — 19,438 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_off00001412.ole embedded-office Embedded OLE/CFB Office body inside ole container at offset 0x1412 19438 bytes
SHA-256: 22663287ce0b6e3323f603e95c5c5851278f7cc27a4d4d0654e990434b247186
Detection
ClamAV: Win.Trojan.Silvina-1
Obfuscation or payload: unlikely

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