Malicious RTF — malware analysis report

Static analysis result for SHA-256 c7cfdbdda45cd22b…

MALICIOUS

RTF

535.5 KB First seen: 2021-09-29
MD5: 78f1a8e2624cdc5784003fa279563268 SHA-1: a4f284a48cdb1a870d89c096e5923f55ff667a5e SHA-256: c7cfdbdda45cd22bd438e51e14a75c1cb7594a83355d69adbd534316a80e6aa1
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 manipulation, specifically related to Composite Monikers and the CVE-2017-8570 vulnerability. This vulnerability is known to facilitate the dropping and execution of script files, such as SCT files, which are likely used to deliver a secondary payload. The presence of ".objdata" sections and related heuristics strongly suggests an exploit targeting OLE object handling within the RTF parser.

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 171558 bytes
SHA-256: d7e24c0b302d3abb6e303aad7091ce88ba3670b7ab6d1409a36a027b2c843390
objdata_01_off00057a67.bin rtf-objdata-decoded RTF \objdata at offset 0x57A67 2632 bytes
SHA-256: 9d9bc825f2fa5e0ed8db7dce6823e199ad9c775873472d42887214589f205470
objdata_02_off0005900a.bin rtf-objdata-decoded RTF \objdata at offset 0x5900A 12297 bytes
SHA-256: 44deae4627fee3c44f54d5bd10477ec2e17f4c08135f08e2417832e36d10d037

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