Gandcrab — RTF malware analysis

Static analysis result for SHA-256 1249a15cb3ff8ebb…

MALICIOUS

RTF

376.5 KB First seen: 2019-05-31
MD5: 77a45127c13103a48082e0c83ccc4d45 SHA-1: 7c5734a6afffd8d969e5ceb4fa813814d4e6f11f SHA-256: 1249a15cb3ff8ebbd9c92ee97dac7624d820cfe2bde72698fca26151ee5b80e8
344 Risk Score

Malware Insights

Gandcrab · confidence 95%

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

The sample is an RTF document that leverages the CVE-2017-8570 vulnerability, which is known to drop SCT scripts. The presence of OLE object data and a PE header within the hex data strongly indicates the embedded artifact is a malicious executable. ClamAV detections confirm this, identifying the sample as Win.Dropper.Gandcrab-7077551-0, a known ransomware family.

Heuristics 8

  • 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.
  • 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.Dropper.Gandcrab-7077551-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Dropper.Gandcrab-7077551-0
  • 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 8 \objdata section(s) — embedded OLE objects
  • 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 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00003af4.bin rtf-objdata-decoded RTF \objdata at offset 0x3AF4 885 bytes
SHA-256: eeabec211f2ccdc2d7c9de123e145457e6ea1837722e08b7b8d755219cd5056e
objdata_01_off00004211.bin rtf-objdata-decoded RTF \objdata at offset 0x4211 612 bytes
SHA-256: c62851521e10316dfd43f2b6ee67cc27e2a24456bb346c8fa9dc4a6d6e21d526
objdata_02_off0000470b.bin rtf-objdata-decoded RTF \objdata at offset 0x470B 482 bytes
SHA-256: 8f35162cb7523f92e9f44d62d12eded23d00d10857cb163693e107bc76bbe0d8
objdata_03_off00004b03.bin rtf-objdata-decoded RTF \objdata at offset 0x4B03 850 bytes
SHA-256: f4d52089bdd4e315fef23608700d3284f76fb6b468ae29aa8a1c54a5ef0a4a01
objdata_04_off0000520e.bin rtf-objdata-decoded RTF \objdata at offset 0x520E 2633 bytes
SHA-256: fe11c27d916ab897eb94064e9631d8a29c847a6db39259bef31578da8d19fdf5
objdata_05_off0000670b.bin rtf-objdata-decoded RTF \objdata at offset 0x670B 2601 bytes
SHA-256: 67ff079a9b0f053ca2843811d9da7a8fdedc7d9d377ef39d09dde148b9657c7f
objdata_06_off00007ba9.bin rtf-objdata-decoded RTF \objdata at offset 0x7BA9 176938 bytes
SHA-256: 6ce3a7d13bed9d4d9576670d4845f11e89f6e0583757bf5432df9a0c937ece67
Detection
ClamAV: Win.Dropper.Gandcrab-7077551-0
Obfuscation or payload: likely
Carved artifact entropy is 7.86, consistent with packed or encrypted content.

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