Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 4100549b9da5effa…

MALICIOUS

RTF / .DOC

1.96 MB First seen: 2022-02-22
MD5: cb15ba4cd74138ec221502127a9c3c08 SHA-1: 4705e0fa0cc797d282dc4f441d6c2f38a8b3fbac SHA-256: 4100549b9da5effac912ffe94fca5c571dc0bcb268f5b90c5449a2832e0d40a6
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability through the Equation Editor. This indicates an attempt to execute arbitrary code. The presence of `Equation.3` as a ProgID strongly suggests the use of this known exploit. The decoded object data likely contains further malicious functionality, such as downloading and executing a second-stage payload.

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
b016dc7c1d50981207a1667ade8093c4e03f090d7f2f5dafa29222fd566e6e22		 rtf-objdata-decoded RTF \objdata at offset 0x1347 26963 bytes
objdata_01_off00019ff8.bin
7271b266ae613b3f0f4a2339cdc62b69633b07c00e19c66830febcf36614100d		 rtf-objdata-decoded RTF \objdata at offset 0x19FF8 461830 bytes

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