Malicious RTF — malware analysis report

Static analysis result for SHA-256 ce202bfc770b0198…

MALICIOUS

RTF

31.1 KB Authoring application: Riched20 6.3.9600 First seen: 2021-06-30
MD5: e6b1d0725a6f8792495ca4babedb2863 SHA-1: 0df64827c85a08d0b2f895b1dfe6fd4c8ea46a9d SHA-256: ce202bfc770b0198d4c1c6ffb6f4d703985d9239e8e959a990ebaab06b22ed11
382 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of exploitation for CVE-2017-11882, specifically related to the Equation Editor OLE object. The presence of ".objdata" and ".objupdate" sections, along with the Equation Editor CLSID and a critical ClamAV detection for Rtf.Exploit.CVE_2017_11882, strongly suggests this vulnerability is being leveraged. The embedded URL points to a WebDAV server, likely used to host and serve the secondary payload.

Heuristics 9

  • Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882
    Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
  • ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
  • Equation Editor object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.3' references Equation Editor
  • Suspicious extracted artifact critical EXTRACTED_FILE_STATIC_TRIAGE
    One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
  • \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 4 \objdata section(s) — embedded OLE objects
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object
  • Embedded URL info EMBEDDED_URL
    One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.
    URL https://webdav.fxt6.com In RTF body

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000100.bin rtf-objdata-decoded RTF \objdata at offset 0x100 3546 bytes
SHA-256: 4e33b312ebd19cc3c05f971885261e8eb664f811b524998a027a80048cb251a3
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): https://webdav.fxt6.com Static shellcode analysis recovered command string(s): cmd.exe /c start https://webdav.fxt6.com &AA C
objdata_01_off00001fe2.bin rtf-objdata-decoded RTF \objdata at offset 0x1FE2 3546 bytes
SHA-256: 46caf7592c61ce2bcd6ad125006417c1fc165fdb1d8c4561cba1d91b28d3ddeb

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