Vbkryjetor — RTF malware analysis

Static analysis result for SHA-256 20d8f602b0ec3d6a…

MALICIOUS

RTF

1.44 MB First seen: 2019-03-18
MD5: a7eeb458c3d617daf8e285276d737f9e SHA-1: c7be76194fc64155e8b163ed9e7d307f38dea828 SHA-256: 20d8f602b0ec3d6a21dea9abf267c273da0cdca3d439d3952583e7a403dc5116
464 Risk Score

Malware Insights

Vbkryjetor · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains multiple indicators of exploitation, including the use of a Composite Moniker and the Equation Editor CLSID, pointing to CVE-2017-8570. This vulnerability is known to drop a SCT script, which is likely the payload. ClamAV detection of Win.Malware.Vbkryjetor-6992847-0 further confirms the malicious nature of the embedded artifact.

Heuristics 11

  • Composite Moniker — CVE-2017-8570 (drops SCT script) critical CVE related CVE_2017_8570
    RTF \objdata decodes to OLE data containing the Composite Moniker — CVE-2017-8570 (drops SCT script) CLSID — the vulnerable control/moniker is embedded directly in the document's object stream, the delivery shape of this exploit. RTF objects auto-render when Word opens the file.
  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • ClamAV: Win.Malware.Vbkryjetor-6992847-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Malware.Vbkryjetor-6992847-0
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • \objupdate forces OLE activation high RTF_OBJUPDATE
    RTF contains \objupdate — forces automatic OLE object instantiation when the document is opened, bypassing user interaction. Almost exclusively seen in Equation Editor exploit documents.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1486KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 7 \objdata section(s) — embedded OLE objects
  • OlePres presentation stream in RTF OLE object medium RTF_OLEPRES_STREAM
    RTF contains an embedded OLE object with an OlePres presentation stream. OlePres is an OLE presentation marker and is not enough on its own to identify CVE-2025-21298.
  • Suspicious extracted artifact info EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL http://schemas.microsoft.com/office/word/2003/wordml In RTF body
    • https://www.globalsign.com/repository/0In RTF body
    • http://crl.globalsign.com/gs/gstimestampingg2.crl0TIn RTF body
    • http://secure.globalsign.com/cacert/gstimestampingg2.crt0In RTF body
    • https://www.globalsign.com/repository/03In RTF body
    • http://crl.globalsign.net/root.crl0In RTF body

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000002c.bin rtf-objdata-decoded RTF \objdata at offset 0x2C 884 bytes
SHA-256: 08cb831cfd094f7193857584f98ebb419e336c73f0191f78a94fb322b6fcad85
objdata_01_off00005f41.bin rtf-objdata-decoded RTF \objdata at offset 0x5F41 33559 bytes
SHA-256: a1cd204187d3969a56ef0de9c9edeed485f313bdb6eeb1b0ba1a700926216e78
objdata_02_off000165a2.bin rtf-objdata-decoded RTF \objdata at offset 0x165A2 697900 bytes
SHA-256: 957d176e5f79e9062c9d0a3b34e2f4d8bac834bb5d681f30ab324ff7d683fe36
Detection
ClamAV: Win.Malware.Vbkryjetor-6992847-0
Obfuscation or payload: likely
Carved artifact entropy is 7.62, consistent with packed or encrypted content.
objdata_03_off0016b238.bin rtf-objdata-decoded RTF \objdata at offset 0x16B238 382 bytes
SHA-256: 7c829894502990522aaee3764e10dad03b3c7476dec48c4e1d128bb9b9774910
objdata_04_off0016b568.bin rtf-objdata-decoded RTF \objdata at offset 0x16B568 789 bytes
SHA-256: 87caf099a20fd4563d975979583365d98bc376a5fd992193cf5da7686fc18198
objdata_05_off0016bbf9.bin rtf-objdata-decoded RTF \objdata at offset 0x16BBF9 2633 bytes
SHA-256: 1feb5f150bb35566d1a01fc59a357dc0ea34bc7498e0ec99bd939f6f848044b0
objdata_06_off0016d103.bin rtf-objdata-decoded RTF \objdata at offset 0x16D103 4679 bytes
SHA-256: 0e2ce9d01b0df41beca1d9d003ff4bfe3998a96192a53992dd35145a081e0a27

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