Malicious RTF — malware analysis report

Static analysis result for SHA-256 bb7cbb101b2f6e4a…

MALICIOUS

RTF

16.8 KB First seen: 2022-09-29
MD5: 402884798f8ea1edd23cd7c3764e513b SHA-1: a41aadf5957f479ccc9811ab1e7d475f4dc91780 SHA-256: bb7cbb101b2f6e4a560a22a32f5ea4c52a9f4c8faa23c476944d171ae2b30f36
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 User Execution: Malicious File T1059.005 PowerShell T1027 Obfuscated Files or Information

The RTF document contains an embedded OLE object with a ProgID indicative of Equation Editor, triggering heuristics related to CVE-2017-11882. The ".objupdate" directive forces OLE activation, and the document body contains a lure instructing the user to 'Enable editing', suggesting a malicious document designed to exploit this vulnerability for arbitrary code execution.

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_off000020bb.bin
f5bf19a1d59705ea00bfde626135e02ab25976d603731f8bf00904a20bf19553		 rtf-objdata-decoded RTF \objdata at offset 0x20BB 1732 bytes

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