Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 8d3ead1a4149580c…

MALICIOUS

RTF / .DOC

359.0 KB First seen: 2022-10-28
MD5: 10215dddffc086202b23f3069eb14a1c SHA-1: a93ef33d7b7aef8b2e4296e6644922dc96393e70 SHA-256: 8d3ead1a4149580c6019ff682e2e77c40391cb01799aec3d25f1c7e6d369517e
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic

The document uses a lure to trick the user into enabling editing, which is a common tactic for macro-based malware delivery. The critical heuristic firing for CVE-2017-11882 activation related to Equation Editor strongly suggests exploitation of this known vulnerability to execute arbitrary code. No scripts were extracted, but the RTF structure and heuristics point to a malicious OLE object designed to exploit the Equation Editor vulnerability.

Heuristics 6

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • \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 1 \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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000006e2.bin
1bd41a0fe7bc55ad6d2aa886470fe342829c37b0fee520d9444a5bd8f459084b		 rtf-objdata-decoded RTF \objdata at offset 0x6E2 1647 bytes

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