Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 b7e15dbfe37eaa29…

MALICIOUS

RTF / .DOC

137.6 KB First seen: 2022-10-21
MD5: 17e36993d889c30458c9c4b7b0fa0d47 SHA-1: 3c9235ba5876e895ec05536875f5145ab89c09fc SHA-256: b7e15dbfe37eaa29a5ff341db4913246466b0d1acc5b5b71d85665a7a7a45978
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 User Execution 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 leverages the Equation Editor vulnerability (CVE-2017-11882). The document body contains a lure instructing the user to 'Enable editing', a common tactic to bypass security measures. The presence of the `eQUATIOn.3` ProgID strongly indicates 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.
  • 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 1 \objdata section(s) — embedded OLE objects
  • 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_off00000f01.bin
b301c9d677d756b9bcd0889aa0a6ecca02bc13e0d2cf9d51ba5fda1a33062d31		 rtf-objdata-decoded RTF \objdata at offset 0xF01 1400 bytes

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