Gandcrab — RTF malware analysis

Static analysis result for SHA-256 aa548c862c4ea0c6…

MALICIOUS

RTF

460.6 KB First seen: 2019-05-16
MD5: 299c3e3f9daa415e47732ba1b6208f8e SHA-1: 2d233eaf61b1640cee99947dc14f3dd8dbe1ad5a SHA-256: aa548c862c4ea0c6193ad25999191bb344a4a3b20112fe2de1e3ea8babb0ca90
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.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 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 196636 bytes
SHA-256: 56a893ac2fb7832d42d509d6067b56d48febbebdfa508fcd1ae0f1ad21400aa1
Detection
ClamAV: Win.Dropper.Gandcrab-7077551-0
Obfuscation or payload: likely
Carved artifact entropy is 7.89, consistent with packed or encrypted content.
objdata_01_off000690e9.bin rtf-objdata-decoded RTF \objdata at offset 0x690E9 11417 bytes
SHA-256: 5d6cfe4c5d1aa428e7c0f5e3f03a769703c8abf56b2cd296a4c4e881ac0011e7
objdata_02_off0006ea53.bin rtf-objdata-decoded RTF \objdata at offset 0x6EA53 382 bytes
SHA-256: 9d6fa4be1a4a694cfee89268078c9efc8705b1a473fbb09a37ceb2d45104e44b
objdata_03_off0006ed8b.bin rtf-objdata-decoded RTF \objdata at offset 0x6ED8B 789 bytes
SHA-256: 8ab026a3e66d94feae5647d5ac6558412271b58006835755f301bcce43b1e52a
objdata_04_off0006f433.bin rtf-objdata-decoded RTF \objdata at offset 0x6F433 2633 bytes
SHA-256: 1feb5f150bb35566d1a01fc59a357dc0ea34bc7498e0ec99bd939f6f848044b0
objdata_05_off0007095b.bin rtf-objdata-decoded RTF \objdata at offset 0x7095B 4679 bytes
SHA-256: 6bb172535cccd16de71bca846e2bb6df177c56b3a545d6e6314435eabf5d2217

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