Malicious RTF — malware analysis report

Static analysis result for SHA-256 b9c60334d7a4d156…

MALICIOUS

RTF

745.7 KB Created: 2017-12-19 14:32:00 First seen: 2017-12-24
MD5: 82b028f16278d5c5591963a6e5de0d3a SHA-1: 9d508960186ae204290654feb72be8865881d015 SHA-256: b9c60334d7a4d1568785c740de0b80c98d254711f19ce2995bccc1ece57be696
382 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains OLE object data and triggers  objupdate, indicating an attempt to activate embedded objects. The critical heuristic firing for CVE-2017-8759 confirms exploitation of MSXML SAX OLE activation. The embedded URL http://skyyoker.xyz/doc/t.php?stats=send&thread=0 is likely used to download a second-stage payload, as suggested by the RTF_INCLUDE_REMOTE heuristic and ClamAV detection as Rtf.Downloader.

Heuristics 10

  • 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.Downloader.CVE_2017-6336326-3 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Downloader.CVE_2017-6336326-3
  • Reference to CreateProcess API high SC_STR_CREATEPROCESS
    Reference to CreateProcess API
  • Reference to ShellExecute API high SC_STR_SHELLEXEC
    Reference to ShellExecute API
  • Reference to LoadLibrary API high SC_STR_LOADLIBRARY
    Reference to LoadLibrary API
  • Reference to GetProcAddress API high SC_STR_GETPROCADDRESS
    Reference to GetProcAddress API
  • \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.
  • INCLUDETEXT/INCLUDEPICTURE remote URL high RTF_INCLUDE_REMOTE
    RTF document uses INCLUDETEXT or INCLUDEPICTURE with an http:// URL — Word can fetch the remote content on open depending on Office version and external-content settings, enabling remote template injection, NTLM capture via redirects, or payload delivery
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \objdata section(s) — embedded OLE objects
  • 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://skyyoker.xyz/doc/t.php?stats=send&thread=0 In RTF body
    • http://nsis.sf.net/NSIS_ErrorIn RTF body
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0000c568.bin rtf-objdata-decoded RTF \objdata at offset 0xC568 2598 bytes
SHA-256: c866cb233a7e6481a420b77fa97acbd8dfbd260ed0bf56e5559566811c35e556
objdata_01_off0000dc96.bin rtf-objdata-decoded RTF \objdata at offset 0xDC96 2723 bytes
SHA-256: 11a99b4177476326ef2f53209904dd8228a1407111b4cd992526f5c47bef1128

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