Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 93fc37cbf68a1fe6…

MALICIOUS

RTF / .DOC

28.5 KB First seen: 2022-11-04
MD5: 3edcb161e8b986b993c5024cc29f94ac SHA-1: 48ec3858f67c8d311c3b6d709794cd6e4dd33c59 SHA-256: 93fc37cbf68a1fe6c3646e6d12f0f850af6ac3b86b956f95c9eb1a5a4a4c8bc5
200 Risk Score

Malware Insights

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

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability in the Equation Editor to execute arbitrary code. The document body contains a lure instructing the user to 'Enable editing', a common tactic for macro-based malware. The critical heuristic firing for RTF_EQUATION_EDITOR and the high confidence firing for CVE_2017_11882_ACTIVATION_RELATED strongly indicate exploitation of this specific vulnerability.

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.
  • \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_off00005246.bin
826f4d78dbe2ea4b639cea01982eff96b2f478ecb7e600344f98f2df80b17b45		 rtf-objdata-decoded RTF \objdata at offset 0x5246 2006 bytes

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