Malicious RTF — malware analysis report

Static analysis result for SHA-256 a7b7b90493d464ac…

MALICIOUS

RTF

536.5 KB First seen: 2021-10-05
MD5: b0a86e1ef6587ff27d145c0a18704fc0 SHA-1: ff97c286f6d9127f39668e227a100793299d743b SHA-256: a7b7b90493d464acf47902ebd77b362e229137280335d44052ae57dcd09ffcce
240 Risk Score

Malware Insights

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

The RTF document contains multiple indicators of malicious OLE object embedding, specifically related to CVE-2017-8570 which is known to drop SCT scripts. The document body explicitly prompts the user to 'Enable Editing', a common lure to bypass macro security. The exploitation of CVE-2017-8570 facilitates the execution of a script, likely for further payload delivery.

Heuristics 7

  • 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
  • Macro/content-enable lure medium SE_ENABLE_LURE
    Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 3

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000bb0.bin rtf-objdata-decoded RTF \objdata at offset 0xBB0 171550 bytes
SHA-256: c1afafd92c3471f5c8d862212660ab1a41da30d7664d17168ddff93de51c3116
objdata_01_off00057e29.bin rtf-objdata-decoded RTF \objdata at offset 0x57E29 2632 bytes
SHA-256: 9d9bc825f2fa5e0ed8db7dce6823e199ad9c775873472d42887214589f205470
objdata_02_off000593cc.bin rtf-objdata-decoded RTF \objdata at offset 0x593CC 12297 bytes
SHA-256: 44deae4627fee3c44f54d5bd10477ec2e17f4c08135f08e2417832e36d10d037

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