Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 335ead76fc79b418…

MALICIOUS

RTF / .DOC

1.06 MB First seen: 2022-09-29
MD5: 97ae27591cf33b06c71e7400a15b665c SHA-1: ea3f5dca533dfdf1189774ab3ec990de44d6b8d9 SHA-256: 335ead76fc79b41873079b767b2dda0cac610bf8450afef25f604cdf8eddaba3
180 Risk Score

Malware Insights

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

The RTF document contains embedded OLE objects and specifically triggers the CVE-2017-11882 vulnerability related to Equation Editor. This exploit is known to be used for delivering second-stage malware. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates this attack vector. The embedded OLE object is likely designed to execute arbitrary code, facilitating further malicious activity.

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_off000012b8.bin
14a8842a9479c01e46021430b6d49894f09cccd6dc9d0c4a2ca87476448726f3		 rtf-objdata-decoded RTF \objdata at offset 0x12B8 81537 bytes
objdata_01_off0002f152.bin
636022af1c118cbfdb875b9c9e9f1876d2aa6f697aa661a5028ea2cb956d97f9		 rtf-objdata-decoded RTF \objdata at offset 0x2F152 187349 bytes

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