Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 82763668eeb17c60…

MALICIOUS

RTF / .DOC

28.5 KB First seen: 2022-11-07
MD5: 351dd866bb97a62b884b4d9af89ed5ff SHA-1: 17237241694ef04dc69431bf8837977c3fc23dca SHA-256: 82763668eeb17c6042d8bf3f0583d038e60b52cca2ae7f74150a9090b3e93acd
200 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability in the Microsoft Equation Editor. The document body contains a lure instructing the user to 'Enable editing', which would trigger the exploit. The embedded OLE object and specific ProgID 'equaTIoN.3' are strong indicators of this exploit.

Heuristics 6

  • 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 1 \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_off00005aff.bin
e1cc841e7ecee9cc882ed7cf6a41460c7ed9643a36328265385c6f768a32c61c		 rtf-objdata-decoded RTF \objdata at offset 0x5AFF 1671 bytes

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