Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 af4d043de5533766…

MALICIOUS

RTF / .DOC

14.4 KB First seen: 2022-09-30
MD5: 36c2406258dbb9cbd3ca6e8cdd67ae8f SHA-1: 8c6c42f592fe698ba5a37c20e13a407638b46a4e SHA-256: af4d043de553376657f91b0e3c4ddfb3fe9e125e1df3fba2bf4f83e5d26a915f
200 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.005 Visual Basic T1566.001 Phishing: Spearphishing Attachment

The sample is an RTF document containing an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The presence of `RTF_EQUATION_EDITOR` and `CVE_2017_11882_ACTIVATION_RELATED` heuristics strongly indicates this exploit. The `SE_ENABLE_LURE` heuristic suggests the document also contains a lure to trick the user into enabling editing, which is a common delivery mechanism for macro-based malware.

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_off00001990.bin
e406027394d1aff433e09e25ed1c89b3b7ffe6f4816082d9c252648236772433		 rtf-objdata-decoded RTF \objdata at offset 0x1990 1648 bytes

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