Malicious RTF — malware analysis report

Static analysis result for SHA-256 4619a6db1b69710f…

MALICIOUS

RTF

340.8 KB First seen: 2021-09-23
MD5: 6a786c49594e9cdc4c2b6de918a79b38 SHA-1: c208505a41c34874256f105fcccfcb7120343d36 SHA-256: 4619a6db1b69710f73f5bae4f171b9d9d0295e733cc4841cab443b880d4e9fcd
220 Risk Score

Malware Insights

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

The RTF file contains multiple indicators of OLE object embedding and automatic activation, specifically referencing CVE-2017-8570 which is known to drop a script. The presence of ".objdata" and ".objupdate" sections strongly suggests the file is designed to execute embedded content. The exploitation of a composite moniker points to a client-side execution vulnerability.

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_off000007de.bin rtf-objdata-decoded RTF \objdata at offset 0x7DE 75720 bytes
SHA-256: a9f071951fe31a08dd46c84d4d1a550975dcc76d8c4454784e2e4f36ddd967b2
objdata_01_off00026fb9.bin rtf-objdata-decoded RTF \objdata at offset 0x26FB9 2632 bytes
SHA-256: f4c761490fd63fc4aa791746a9a2b588dafd9e2c764f57f0c85377b99ef07062
objdata_02_off0002855c.bin rtf-objdata-decoded RTF \objdata at offset 0x2855C 12297 bytes
SHA-256: 44deae4627fee3c44f54d5bd10477ec2e17f4c08135f08e2417832e36d10d037

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