Malicious RTF — malware analysis report

Static analysis result for SHA-256 bd4386bb61e9be6a…

MALICIOUS

RTF

42.5 KB First seen: 2023-02-16
MD5: a68c4976a2cef7c909424f055791c976 SHA-1: fda59bd0c32aa9ede6223d3e5d5ea2742e9478c1 SHA-256: bd4386bb61e9be6ac59946a8a23ce4cb2abd1ccf476b9881a12a20ee42eea075
200 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object specifically identified as related to CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The presence of \objdata and \objupdate directives strongly suggests an attempt to trigger this exploit upon opening the document, likely leading to the execution of a secondary payload. The document body includes a lure to 'Enable editing', further supporting the malicious intent.

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_off0000480a.bin
adafb7cac49b31bd10fb96e2085940a03c7b52fd79961202cef321413df2c1a7		 rtf-objdata-decoded RTF \objdata at offset 0x480A 1982 bytes

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