Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 c5a6806d5b4514c2…

MALICIOUS

RTF / .DOC

8.8 KB First seen: 2022-08-04
MD5: febbbe8eb7b98c39b600497b2042c785 SHA-1: 54d1dc8825a9c1b172163ceecb1a32e64b8dc9b3 SHA-256: c5a6806d5b4514c237b79a4436655999701f55211acc0acfe4e04e40c730a92d
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic

The RTF document contains an embedded OLE object that exploits CVE-2017-11882 through the Equation Editor. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this exploit. The SE_ENABLE_LURE heuristic suggests the document prompts the user to enable content, a common tactic for macro-based malware delivery.

Heuristics 6

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • 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.
  • \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
  • 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_off00000c7d.bin
d547fb64fd840cf79705b10261b8826c19d6c38c205b9641448005d1e04b4522		 rtf-objdata-decoded RTF \objdata at offset 0xC7D 1517 bytes

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