Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 89ed8fe4a2088384…

MALICIOUS

RTF / .DOC

26.0 KB First seen: 2022-12-23
MD5: d1067c30d4dfa5f8af3f1f029c5e1ff9 SHA-1: 2cb837cdea667dd319505a91d4e72ccbaf42bea7 SHA-256: 89ed8fe4a20883845619bf997f9b5caa92d896a4d6302b4ad1899fe5d1f12927
220 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 through an embedded Equation Editor OLE object. The document body contains a lure related to marketing strategy, and the heuristics indicate that the embedded object is designed to be automatically activated and updated, likely to execute a second-stage payload. The user is prompted to 'Enable editing', a common social engineering tactic to bypass macro security.

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_off000054f7.bin
4d5cb852c6910ccdb00c1b379333365af57a4c54329bdffbdeda86355316e576		 rtf-objdata-decoded RTF \objdata at offset 0x54F7 1360 bytes

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