Malicious RTF — malware analysis report

Static analysis result for SHA-256 ff277d4c8dc465d1…

MALICIOUS

RTF

493.0 KB First seen: 2019-03-18
MD5: 5462fed15c6ae2761ec3cb9ae8519dca SHA-1: 0880b694a944b1ba50bd840b920cc7402244c470 SHA-256: ff277d4c8dc465d1a0bdf2b09c3d885502423ea3da7dd4bd1aeca98bc587d7c1
220 Risk Score

Malware Insights

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

The RTF file contains multiple OLE objects and ".objupdate" directives, indicating it is designed to exploit vulnerabilities. Specifically, the "CVE_2017_8570" heuristic firing confirms the use of a Composite Moniker to drop an SCT script, which is a known technique for executing arbitrary code. The embedded OLE object data, particularly at offset 0xB5D2, is the likely source of this exploit.

Heuristics 6

  • 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.
  • 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 5 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 5

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000025.bin rtf-objdata-decoded RTF \objdata at offset 0x25 228271 bytes
SHA-256: 80f7060ee2f537fe37ed1c4b4bf201ce359f41e82bb2d528f40bdc8ee514fa74
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 8.00, consistent with packed or encrypted content.
objdata_01_off000787f0.bin rtf-objdata-decoded RTF \objdata at offset 0x787F0 1056 bytes
SHA-256: 38e0a590df7eaa9868af736886281809be3c0fe6a6a6ea4e0327baa813cb5642
objdata_02_off0007906c.bin rtf-objdata-decoded RTF \objdata at offset 0x7906C 429 bytes
SHA-256: c861ab3ab7d28ef7b028a69afbbfc89c1f5c98f0be9f15b26f0565b7d5605703
objdata_03_off00079402.bin rtf-objdata-decoded RTF \objdata at offset 0x79402 1351 bytes
SHA-256: fbfe6031f946bf25c25f9783662a0516de4f34007dcfe7ff53f2b540dbc1df3f
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered command string(s): cscript //nologo %vbs%
objdata_04_off00079f0e.bin rtf-objdata-decoded RTF \objdata at offset 0x79F0E 2633 bytes
SHA-256: 1f8de175e345e5b9624b8bb5f76e9d4c1d78de3a7bbc2750e8ea7def36f04cfb