Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 1b83d5ce3df5b28d…

MALICIOUS

RTF / .DOC

29.1 KB First seen: 2022-12-08
MD5: 3d016eab2f7ffcff51f487fea2721dd2 SHA-1: 5254b9b19967a9d496ce0d7247c13393193e348a SHA-256: 1b83d5ce3df5b28d774a428fbabf41a3b21767d03e0fe06620f77f9b7108fee4
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 User Execution: Malicious File T1059.005 PowerShell

The RTF document contains an embedded OLE object with a split Equation Editor ProgID, a known indicator of the CVE-2017-11882 vulnerability. The document also contains a lure instructing the user to 'Enable editing', which is a common technique to bypass macro security settings. The exploitation of CVE-2017-11882 allows for arbitrary code execution, likely to download and run a secondary payload.

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_off0000442d.bin
26573bc506d3839f1f04fd7c090607337efd252e7752a5b69bcb79cc6594f380		 rtf-objdata-decoded RTF \objdata at offset 0x442D 1889 bytes

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