Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 7779d62261110f25…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-23
MD5: 1e30255d9eca3098dea84d133c6bf8dd SHA-1: 80f3b4e1324b6b1010a489351767fcf6d2f1d23e SHA-256: 7779d62261110f25d55afedc111af026cd79bb8fb350c56f70d42be498e4622b
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an RTF document containing embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability through the Equation Editor. This exploit is designed to execute arbitrary code, likely to download and run a secondary payload. The presence of RTF_OBJDATA, RTF_OBJEMB, RTF_EQUATION_EDITOR, and RTF_OBJUPDATE heuristics strongly indicates this exploit vector.

Heuristics 5

  • 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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001347.bin
41084e4e7b89812df61f04c0ea23c21108b18c489f6b751d3ea6064c22bd8f79		 rtf-objdata-decoded RTF \objdata at offset 0x1347 26936 bytes
objdata_01_off00019fc2.bin
7271b266ae613b3f0f4a2339cdc62b69633b07c00e19c66830febcf36614100d		 rtf-objdata-decoded RTF \objdata at offset 0x19FC2 461830 bytes

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