Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 390638174e786d6f…

MALICIOUS

RTF / .DOC

26.4 KB First seen: 2023-01-25
MD5: d7b4ead6fc37ef7315c0118f8039e5fd SHA-1: 70c4b99344efebdfd15c84543a73387e051d9c6e SHA-256: 390638174e786d6f8debc631dcd06acf8e06fe5a80f9dbb6cad409794bf70ff0
200 Risk Score

Malware Insights

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

The sample 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', a common tactic for macro-based malware. The embedded object is designed to activate automatically, likely leading to the execution of 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_off000051df.bin
4003214f07efa34ce20d55c0566d2767ce7ba39a327c4fc935cbaf6ca037ca12		 rtf-objdata-decoded RTF \objdata at offset 0x51DF 1705 bytes

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