Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 131456f26559aed2…

MALICIOUS

RTF / .DOC

146.6 KB First seen: 2022-10-19
MD5: beffab66644e579ca224c743dc802556 SHA-1: 20d0d86d20f5ae7dc539cd3301b9e1091a907434 SHA-256: 131456f26559aed2b9efd3518e1a164d943e9fb64c72a23a5bd0afdc8a82f3a3
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1059.005 Visual Basic T1204.002 Malicious File

The RTF document contains 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 tactic for macro-based malware. The critical heuristic 'RTF_EQUATION_EDITOR' and high heuristic 'CVE_2017_11882_ACTIVATION_RELATED' directly indicate the exploitation of this known 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_off00001a2b.bin
923e45385f8704da55671e6e0638813a926583b8ae478be503853397fc23c48f		 rtf-objdata-decoded RTF \objdata at offset 0x1A2B 1472 bytes

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