Gandcrab RTF malware analysis — malicious · 539fb72bdf91394c

MALICIOUS

RTF

1.73 MB First seen: 2019-11-20

MD5: 50b8604a594416847d4bf39b94d74f35 SHA-1: 1ef29dc0b2c8909070042e5e2ad52d284776c687 SHA-256: 539fb72bdf91394c07d03b40e334d3f0c04081cda4fd26ce22f348df7336e0b1

384 Risk Score

Malware Insights

Gandcrab · confidence 95%

MITRE ATT&CK

T1203 Exploitation for Client Execution

The RTF file contains multiple OLE objects and exhibits characteristics of CVE-2017-8570, indicating it's designed to drop and execute a script. ClamAV detections confirm this, identifying the sample as Win.Dropper.Gandcrab-7077551-0. The embedded OLE objects, particularly objdata_01_off0000e592.bin and objdata_05_off000a3357.bin, likely contain the secondary payload.

Heuristics 9

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.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1812KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 6 \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://schemas.openxmlformats.org/drawingml/2006/main In RTF body
- http://schemas.openxmlformats.org/officeDocument/2006/bibliographyIn RTF body
- http://schemas.openxmlformats.org/officeDocument/2006/customXmlIn RTF body
- http://nsis.sf.net/NSIS_ErrorIn RTF body

Extracted artifacts 6

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off0000de6f.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xDE6F	885 bytes
SHA-256: `eeabec211f2ccdc2d7c9de123e145457e6ea1837722e08b7b8d755219cd5056e`
`objdata_01_off0000e592.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xE592	300748 bytes
SHA-256: `1f5f0fe1cca0e6c2212cc3e3d2d0f02f7125d43675a656a570732d9b12780f54`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.55, consistent with packed or encrypted content.
`objdata_02_off000a1362.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xA1362	482 bytes
SHA-256: `8f35162cb7523f92e9f44d62d12eded23d00d10857cb163693e107bc76bbe0d8`
`objdata_03_off000a1762.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xA1762	850 bytes
SHA-256: `f4d52089bdd4e315fef23608700d3284f76fb6b468ae29aa8a1c54a5ef0a4a01`
`objdata_04_off000a1e77.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xA1E77	2633 bytes
SHA-256: `14aa25c92fc5a24c188c4868fd7dae8e876ae76d0b7e861ca3e3dfc5c207fe10`
`objdata_05_off000a3357.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xA3357	572203 bytes
SHA-256: `2bb9e4da70c3d83fe540ca401ac31ffebc32909343e1d799259615b3844c74d7`
Detection ClamAV: Win.Dropper.Gandcrab-7077551-0 Obfuscation or payload: likely Carved artifact entropy is 7.98, consistent with packed or encrypted content.

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