Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 19373794e0d5477d…

MALICIOUS

RTF / .DOC

13.4 KB First seen: 2022-08-30
MD5: cb9d8ea0ded5694f4fbd3ee7bc2c33eb SHA-1: ff22922b02b8fbb93583b2010e82f66ee27edc86 SHA-256: 19373794e0d5477dc6ae0806ccdefae92b7a651c125cd73199a9742ba4041b3e
220 Risk Score

Malware Insights

MITRE ATT&CK
T1204 User Execution T1204.002 User Execution: Malicious File T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1059 Command and Scripting Interpreter

The sample is an RTF document that contains an OLE object with an obfuscated Equation Editor ProgID. Heuristics indicate that this object is automatically linked and its activation is forced via \objupdate, strongly suggesting exploitation of CVE-2017-11882. The document body contains a lure instructing the user to 'enable editing to view in readable format', which is a common technique to bypass macro security settings and facilitate the execution of malicious content.

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.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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
  • 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_off0000209f.bin
46975be79366ba37311f09f486e3f25c28111825b059956475d174939e1bcdde		 rtf-objdata-decoded RTF \objdata at offset 0x209F 1958 bytes

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