Malicious RTF — malware analysis report

Static analysis result for SHA-256 8b3261840db27ce5…

MALICIOUS

RTF

497.7 KB Authoring application: Riched20 10.0.15063 First seen: 2019-02-20
MD5: bc7adc0cef00102738b36e42c279bad8 SHA-1: a533d448fb03bba431b8b9d87307472544f7afc8 SHA-256: 8b3261840db27ce541d9a82ea1d03ae5da70b4a283c1ce83c8876d9bfac8a737
140 Risk Score

Malware Insights

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

The RTF file contains multiple OLE objects, including embedded objects that trigger activation via \objupdate. The presence of a Composite Moniker and OlePres stream strongly suggests an attempt to exploit OLE object handling vulnerabilities for arbitrary code execution. This is a common technique for delivering malicious payloads via email attachments.

Heuristics 5

  • 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 6 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • OlePres presentation stream in RTF OLE object medium RTF_OLEPRES_STREAM
    RTF contains an embedded OLE object with an OlePres presentation stream. OlePres is an OLE presentation marker and is not enough on its own to identify CVE-2025-21298.

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000f9.bin rtf-objdata-decoded RTF \objdata at offset 0xF9 41320 bytes
SHA-256: ca61d07d71ee31dd9c97f749c4ae3cff2addb8de793681b909877c3a0b467fe5
objdata_01_off00014ca8.bin rtf-objdata-decoded RTF \objdata at offset 0x14CA8 41320 bytes
SHA-256: ac7a4714c2e06e5fa3112a505c1efd96bb3b4e15749397623b9589ef215b7f74

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