Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 1bbed4f6a5b143ad…

MALICIOUS

RTF / .DOC

13.4 KB First seen: 2022-06-21
MD5: 1abfd6dda878b03833bb46646af048d2 SHA-1: 0bbaf5c7c4e5e99e9a835035f53bbe13f4cb1ad8 SHA-256: 1bbed4f6a5b143ade31c6128b1808581c1d8fd6538e7de9b3c82665d21e814aa
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204.002 Malicious File T1559.001 Component Object Model T1059.001 PowerShell

The RTF document contains heuristics indicating the exploitation of CVE-2017-11882 through an embedded Equation Editor object. The ".objupdate" directive forces OLE activation, which is a common technique for exploiting this vulnerability. The document body contains what appears to be garbled text, suggesting it is not intended for direct user consumption but rather as a lure for the exploit. The primary attack vector is the exploitation of the Equation Editor vulnerability to execute arbitrary code.

Heuristics 5

  • 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

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001c3f.bin
a240a24069d98144ce62040150a6331f501ec026fb4ef4d188d1fd700bfde53f		 rtf-objdata-decoded RTF \objdata at offset 0x1C3F 2021 bytes

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