Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 de2c860b0aadc6fa…

MALICIOUS

RTF / .DOC

12.2 KB First seen: 2022-03-29
MD5: c9b1982cb7198d0813d45f753ebc670d SHA-1: aa8844c94e7e42b1c1c9a0edb877ce7e6685b903 SHA-256: de2c860b0aadc6fa94d7d172492a646af029d32a41ea3744ce29f7c6feb58764
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1559 Component Object Model Hijacking T1059.001 PowerShell T1027 Obfuscated Files or Information

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to execute arbitrary code. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates this exploit. The `RTF_OBJUPDATE` heuristic suggests that the embedded OLE object is automatically activated upon opening the document, leading to the execution of the exploit. No document body text was available for analysis, but the heuristics confirm the exploit's nature.

Heuristics 5

  • 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 2 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001fd5.bin
20f6ee3fbd4b4817904c222aa84696362428f139444e24b4335a90e5395494f0		 rtf-objdata-decoded RTF \objdata at offset 0x1FD5 1895 bytes

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