Malicious RTF — malware analysis report

Static analysis result for SHA-256 403a3b9c7e92db0a…

MALICIOUS

RTF

10.6 KB First seen: 2022-09-30
MD5: 5a2f4120959bba253302ffbffb93990e SHA-1: dae5f20b657d553545df0dc2e40a5492927c2a0c SHA-256: 403a3b9c7e92db0a937644f33931868d6c21f4526981dd4b20cbe3591fb2ce99
220 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically identified as related to Equation Editor, triggering critical heuristics for CVE-2017-11882. The presence of \objupdate and \objdata sections, along with a lure instructing the user to 'Enable editing', strongly indicates an attempt to exploit this known vulnerability for initial code execution. The specific exploit mechanism points to a classic dropper behavior.

Heuristics 6

  • 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.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • 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_off000009bc.bin
26eef6c7ac31c5d49694451c30af6721bf1c14eb951175ea5358a5cacb419f0a		 rtf-objdata-decoded RTF \objdata at offset 0x9BC 1670 bytes

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