Rtf.Dropper.Agent-9965975-1 — RTF malware analysis

Static analysis result for SHA-256 fd01a4fbaefb4626…

MALICIOUS

RTF

148.8 KB Created: 2018-09-19 14:30:00 First seen: 2019-01-11
MD5: 7c0affc45b9fd365e1b13ff2ea5215c3 SHA-1: 28697096ee82243cee9449494aa1be08a9de0b72 SHA-256: fd01a4fbaefb4626aedb07d88eba9f526fb4183f68856ca6fffc99a5baabd114
462 Risk Score

Malware Insights

Rtf.Dropper.Agent-9965975-1 · confidence 95%

MITRE ATT&CK
T1203 Exploitation for Client Execution

The RTF document contains multiple critical heuristic firings indicating exploitation of CVE-2017-11882 (Equation Editor) and CVE-2017-8759 (MSXML SAX OLE activation). These vulnerabilities are used to embed and execute malicious code, likely a second-stage payload, from the URL http://104.238.171.221/YN0_jiUmzDah4cU.dat. The ClamAV detection name further supports this dropper functionality.

Heuristics 12

  • 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.
  • Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED
    RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
  • ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION
    ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
  • PE header (with DOS stub) in hex data critical RTF_MZ_HEX
    Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
  • \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.
  • Package object class high RTF_OBJCLASS_PACKAGE
    OLE Package object — can wrap arbitrary files
  • 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
  • Suspicious extracted artifact medium 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.
  • 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://104.238.171.221/YN0_jiUmzDah4cU.dat In 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_off00005e76.bin rtf-objdata-decoded RTF \objdata at offset 0x5E76 33098 bytes
SHA-256: 73e9858170249aa81d3c154c81c8e15f52579e499d052a9d86fe5819897d4de8
objdata_01_off00020a35.bin rtf-objdata-decoded RTF \objdata at offset 0x20A35 8642 bytes
SHA-256: 0c351cd4d2e2cec18fc1779e1cf9dadf8f2a6db576cce9511d6fd5b1f6cbd584
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: SC_PEB_ACCESS