Malicious RTF — malware analysis report

Static analysis result for SHA-256 85d6640af8e62af3…

MALICIOUS

RTF

536.4 KB First seen: 2019-01-12
MD5: 13f4ea4574ae9fbfe00ac1885ced9e1e SHA-1: dc64f11bfe464945aa6073c35d19ecccfdad1105 SHA-256: 85d6640af8e62af30c55128e5eab868a2588e28da516b2e59bc5293bf60fd952
182 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.
  • 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 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.

Extracted artifacts 7

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000025.bin rtf-objdata-decoded RTF \objdata at offset 0x25 229 bytes
SHA-256: bdf6de0a64b3411ca5229f989a8704bb9f2ac8eac0d3b0c83ab62136585dd012
objdata_01_off0000021e.bin rtf-objdata-decoded RTF \objdata at offset 0x21E 260907 bytes
SHA-256: 9605f140e1f70502de627373d6c8beeb2416e8613a80da4170266d839c254395
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Carved artifact entropy is 7.91, consistent with packed or encrypted content.
objdata_02_off0008337d.bin rtf-objdata-decoded RTF \objdata at offset 0x8337D 1123 bytes
SHA-256: 263c6a332f8bed14e4d9417cab11f921ef8d301d5b5d655b5a43179ea58c7434
objdata_03_off00083c7c.bin rtf-objdata-decoded RTF \objdata at offset 0x83C7C 636 bytes
SHA-256: beeb549ebc57e264e8e77fa6b4cfd820bf95bef53865f2e41c70d776aef38923
objdata_04_off000841ac.bin rtf-objdata-decoded RTF \objdata at offset 0x841AC 404 bytes
SHA-256: 392cac683130eb6402c5b549f0e7d1653f531eebb9a09e8b26c73d30cf6c8b98
objdata_05_off00084510.bin rtf-objdata-decoded RTF \objdata at offset 0x84510 937 bytes
SHA-256: e21955e19ee5e9c33caa29d20574aba20d6cc02b855734ac20377ad351eddf3c
objdata_06_off00084ce0.bin rtf-objdata-decoded RTF \objdata at offset 0x84CE0 2633 bytes
SHA-256: ce081fd28fe7177ff803b92dfff0940839fdacbc316318ce15cbf8889540f4f0