Win.Dropper.Nemesis-6646739-0 — RTF malware analysis

Static analysis result for SHA-256 816c9d6d36399c0e…

MALICIOUS

RTF

475.2 KB First seen: 2018-09-04
MD5: 1fc9b5094b733179f1033890c79b2e41 SHA-1: 3f42f46d0398ae70f3435707c849fa7b7b9c62d3 SHA-256: 816c9d6d36399c0ef5bb8d0334ef40ba6668cd043be104a4ec3f4291ae1a4b86
442 Risk Score

Malware Insights

Win.Dropper.Nemesis-6646739-0 · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF file contains OLE object data and triggers CVE-2017-8570, which is known to drop SCT scripts. The embedded URL http://test1.ru/newbuild/t.php?thread=0&stats=send is likely used to download and execute a second-stage payload. ClamAV detections further confirm its malicious nature as a dropper.

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.
  • 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.Nemesis-6646739-0 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Win.Dropper.Nemesis-6646739-0
  • 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.
  • INCLUDETEXT/INCLUDEPICTURE remote URL high RTF_INCLUDE_REMOTE
    RTF document uses INCLUDETEXT or INCLUDEPICTURE with an http:// URL — Word can fetch the remote content on open depending on Office version and external-content settings, enabling remote template injection, NTLM capture via redirects, or payload delivery
  • Suspicious extracted artifact high 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.
  • OLE object data medium RTF_OBJDATA
    RTF contains 6 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • 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://test1.ru/newbuild/t.php?thread=0&stats=send In RTF body
    • http://nsis.sf.net/NSIS_ErrorIn RTF body

Extracted artifacts 6

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000030.bin rtf-objdata-decoded RTF \objdata at offset 0x30 1091 bytes
SHA-256: 794eca03894fb80257e7ec09b5720553462a13ee66353920334e63fd4fb81c75
objdata_01_off00001a19.bin rtf-objdata-decoded RTF \objdata at offset 0x1A19 331 bytes
SHA-256: b4a983960ffa3c0f44b24d291ce25aafcfd5a9b8e76555d8bcdabccfd469ee33
objdata_02_off00001ce7.bin rtf-objdata-decoded RTF \objdata at offset 0x1CE7 233633 bytes
SHA-256: b8b3b8504d3ad7a044a417150ae219ab7f4033ba14f82dcb2640892d747a4004
Detection
ClamAV: Win.Dropper.Nemesis-6646739-0
Obfuscation or payload: likely
Carved artifact entropy is 7.89, consistent with packed or encrypted content.
objdata_03_off00073e61.bin rtf-objdata-decoded RTF \objdata at offset 0x73E61 2417 bytes
SHA-256: fa388763913a4a08c9679c205158bd501c7a427933f11f624e51547f1f3181a9
objdata_04_off0007517b.bin rtf-objdata-decoded RTF \objdata at offset 0x7517B 718 bytes
SHA-256: ee3767dfb57e3c45452d51fff662e3cc9d4f9791085989f8cfbaf944e3947c84
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): WScript.Shell")
objdata_05_off00075759.bin rtf-objdata-decoded RTF \objdata at offset 0x75759 2633 bytes
SHA-256: 1b11531569c98284e74e6ae4c14275a0ab013edb5d6151ea140c1c38c40ac41e

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