Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 519b239291af0798…

MALICIOUS

RTF / .DOC

11.7 KB First seen: 2022-10-31
MD5: 6d5126b7c476842edd507df19ab387c9 SHA-1: 8e781615b07fd0d19f5e9dece6c8d5812497f663 SHA-256: 519b239291af07989c096d643452debcce67d155dcdc113101357096978c6d7b
200 Risk Score

Malware Insights

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

The sample is an RTF document containing an embedded OLE object that exploits CVE-2017-11882 through the Equation Editor. The document body contains a lure instructing the user to enable editing, a common technique for macro-based malware delivery. The embedded object's ProgID, 'EQUAtION.3', is a strong indicator of this exploit.

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_off0000160e.bin
3641928b75b02b3fb506e4872eff0a6eccead2f2ebcd024613f59dd89e968dfc		 rtf-objdata-decoded RTF \objdata at offset 0x160E 2074 bytes

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