Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 d8f3db1e484b4948…

MALICIOUS

RTF / .DOC

5.6 KB First seen: 2022-11-18
MD5: 7b236fa80e3dc56d0217bd86ab9d2a7d SHA-1: 52bb1ed001b9fcc0542c47431eb950d8b9daf362 SHA-256: d8f3db1e484b494847636aa72ede63f3c1b5e16844c491507b2ec3294d81fe26
180 Risk Score

Malware Insights

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

The sample is an RTF document that contains an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The heuristics indicate that the object is obfuscated and designed to activate, which is a common technique for delivering a secondary malicious payload. No document body text or scripts were extracted, but the exploit itself is sufficient evidence of malicious intent.

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 1 \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_off00000915.bin
349d72b7e8c9eef7686569ce3f81ca5e758ff1667cfa06986faea1771a2b121f		 rtf-objdata-decoded RTF \objdata at offset 0x915 1647 bytes

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