Malicious RTF — malware analysis report

Static analysis result for SHA-256 83d375a39203edb2…

MALICIOUS

RTF

1.88 MB First seen: 2019-03-10
MD5: 8d3e20f727487d79ebd15057a4fab48c SHA-1: b030b66d7dec552da5f2af5c234bcf171053c0ce SHA-256: 83d375a39203edb2855a69f5f5b7e35cfeb44c71591662a174bf50f1a5dc225d
242 Risk Score

Malware Insights

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

The RTF file contains multiple indicators of malicious activity, including the presence of OLE objects and a Composite Moniker, strongly suggesting exploitation of CVE-2017-8570. This vulnerability is known to drop and execute SCT scripts. The heuristic 'CVE_2017_8570' specifically points to this exploit, which facilitates client execution by dropping a script. The presence of a large, hex-encoded OLE object further supports the likelihood of a hidden payload.

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.
  • \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 ~1385KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 7 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Suspicious extracted artifact medium 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

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000025.bin rtf-objdata-decoded RTF \objdata at offset 0x25 205 bytes
SHA-256: 75a725fc96463ea024899f12597b26031b1a5d84ddd2de407d47914073b3db59
objdata_01_off000001ea.bin rtf-objdata-decoded RTF \objdata at offset 0x1EA 692939 bytes
SHA-256: d4d8c74b7b6aa0ba2d3123e0d21916e3d0e5fa670bdf812b7ce2d09737be9e73
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: SC_MSF_REVERSE, SC_STR_VIRTUALALLOC, SC_STR_LOADLIBRARY Static shellcode analysis recovered API/import strings: LoadLibraryExA, VirtualAlloc, GetProcAddress, ExitProcess, LoadLibraryA, VirtualProtect
objdata_02_off001ad118.bin rtf-objdata-decoded RTF \objdata at offset 0x1AD118 1068 bytes
SHA-256: 2b28d78ceb2a564ae30f2b6865926b068f3f920a373c2e3fc4cb865091eddd89
objdata_03_off001ad9a3.bin rtf-objdata-decoded RTF \objdata at offset 0x1AD9A3 100044 bytes
SHA-256: 88ab095311731d817bab9aa532589fc187a9db8b3812b212a78fd135e34d4333
objdata_04_off001de76d.bin rtf-objdata-decoded RTF \objdata at offset 0x1DE76D 369 bytes
SHA-256: 3c0b4878e98d51d984a06b9ba36e54869ecd67e41f335730fced4ca28976d877
objdata_05_off001dea83.bin rtf-objdata-decoded RTF \objdata at offset 0x1DEA83 890 bytes
SHA-256: 21dcdf875b1972c61c0e8c2c2123f9a95c8f29fb4a2cf8bf52511b328881de8e
objdata_06_off001df1de.bin rtf-objdata-decoded RTF \objdata at offset 0x1DF1DE 2633 bytes
SHA-256: 27c6d10cfe7974ebf40c1200cc005f9878cc37b7d49ece9cbc396d700c38918a

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