Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 12adf2447a7a0290…

MALICIOUS

RTF / .DOC

23.6 KB First seen: 2022-11-16
MD5: 2c06040a14c4f725e11e267a994424c4 SHA-1: 0f4cb0f66ec15ad69f9589f0accfe02dfaf0c60e SHA-256: 12adf2447a7a0290eaa584df416a5289abc98e5dd339ff801aa8cb9ec44883e2
200 Risk Score

Malware Insights

MITRE ATT&CK
T1566.001 Spearphishing Attachment T1204.002 Malicious File T1059.005 Visual Basic T1129 Execution through API

The file is an RTF document containing an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). The document body includes a lure instructing the user to 'Enable editing', which is a common technique to bypass macro security settings and trigger the exploit. The exploit likely leads to the execution of a second-stage 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_off00004423.bin
749e20df8321505841f52a411e5d9f109af5d66c3d19056b88cf243ad71b3040		 rtf-objdata-decoded RTF \objdata at offset 0x4423 1890 bytes

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