Malicious RTF — malware analysis report

Static analysis result for SHA-256 575c101b1b311158…

MALICIOUS

RTF

343.7 KB Authoring application: Riched20 6.3.9600 First seen: 2021-09-18
MD5: cfac16a712b28a648186ad62e116ef17 SHA-1: 68bede61d43d9c7ba4a0d1eed154967f793fbad6 SHA-256: 575c101b1b311158ba22684478f66972e8826338c2804d60ff62b2d97dc3bc62
220 Risk Score

Malware Insights

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

The RTF document contains multiple indicators of malicious OLE object manipulation, specifically related to CVE-2017-8570. This vulnerability allows for the composite moniker to drop and execute a script, which is a common technique for initial execution of malware. The document body contains garbled text, suggesting it may be a lure for a scam or phishing attempt, but the primary malicious activity is the exploitation of the CVE.

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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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 3 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000013a6.bin rtf-objdata-decoded RTF \objdata at offset 0x13A6 75692 bytes
SHA-256: 9056c943af4f846a9749198e4c75e93846d5842f025d8b20f7a08ed804b87b68
objdata_01_off00027b45.bin rtf-objdata-decoded RTF \objdata at offset 0x27B45 2632 bytes
SHA-256: 10a6f8600e8524cd28573939a4ae1bdfdf968f5507d04011336569618d3ad498
objdata_02_off000290e8.bin rtf-objdata-decoded RTF \objdata at offset 0x290E8 12297 bytes
SHA-256: 44deae4627fee3c44f54d5bd10477ec2e17f4c08135f08e2417832e36d10d037

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