Gandcrab — RTF malware analysis

Static analysis result for SHA-256 56cf0591ab1d2fe8…

MALICIOUS

RTF

695.1 KB First seen: 2019-01-12
MD5: 0ad7c8e9fcdd705bc432751a2e60c682 SHA-1: fe3c917211b3b457c5c915bcd4093d310b2fb239 SHA-256: 56cf0591ab1d2fe8ac03b355e5773edd0cf57bc44efdebf6a0bad6dae9852c96
424 Risk Score

Malware Insights

Gandcrab · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple critical heuristic firings indicating the exploitation of CVE-2017-8570 through an embedded OLE object, specifically leveraging the Equation Editor. ClamAV detections confirm this as Win.Dropper.Gandcrab-7077551-0, suggesting it acts as a dropper for the Gandcrab ransomware. The embedded OLE object likely contains shellcode or a script designed to download and execute the final payload.

Heuristics 10

  • 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.Ransomware.Gandcrab-6700520-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Ransomware.Gandcrab-6700520-0
  • 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.
  • 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://nsis.sf.net/NSIS_Error In RTF body

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000031.bin rtf-objdata-decoded RTF \objdata at offset 0x31 338426 bytes
SHA-256: 133dbe655f76e6fb6e6e48125e66e914c7cddddee2c4cd66a36f55d9f37bda45
Detection
ClamAV: Win.Ransomware.Gandcrab-6700520-0
Obfuscation or payload: likely
Carved artifact entropy is 7.95, consistent with packed or encrypted content.
objdata_01_off000a8f2d.bin rtf-objdata-decoded RTF \objdata at offset 0xA8F2D 612 bytes
SHA-256: c62851521e10316dfd43f2b6ee67cc27e2a24456bb346c8fa9dc4a6d6e21d526
objdata_02_off000a942d.bin rtf-objdata-decoded RTF \objdata at offset 0xA942D 482 bytes
SHA-256: 5335740b0cd34b41db1162eb5c2c304105d851714fd2d00522c05285a960dc0e
objdata_03_off000a982d.bin rtf-objdata-decoded RTF \objdata at offset 0xA982D 840 bytes
SHA-256: da400f4c46a7615175945784cc67535e05561f169d0cafa1a77934fc58325e84
objdata_04_off000a9f3b.bin rtf-objdata-decoded RTF \objdata at offset 0xA9F3B 2247 bytes
SHA-256: 992c836552ac8953ea96f98fe3fdf2f015904931030078610b1ec4c608451d62
objdata_05_off000ab15f.bin rtf-objdata-decoded RTF \objdata at offset 0xAB15F 4678 bytes
SHA-256: 3caadc4b45498318dcaaef0e9aab441c82ea48680132276b22d9cf579b9252e5

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