Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 bf009ac1b3f046c2…

MALICIOUS

RTF / .DOC

26.0 KB First seen: 2022-11-25
MD5: 03155cbe14d0f635c944d11de1f13516 SHA-1: 39034545bcea63c84b20a107df1c0bae88112a1b SHA-256: bf009ac1b3f046c23a2b4bbe3ad91ea7d6a6431007c0cf4bb4de095bf10d1511
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an RTF document containing an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The document body includes a lure instructing the user to 'Enable editing' to view the content. The presence of the RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this known vulnerability to achieve code execution.

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_off00004fd1.bin
da5a6aa9d60246f389891e7530851435cfb24e37bdd6bb467a87f646d2d60e22		 rtf-objdata-decoded RTF \objdata at offset 0x4FD1 1713 bytes

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