Malicious RTF — malware analysis report

Static analysis result for SHA-256 cd3d4335fc4afba4…

MALICIOUS

RTF

66.3 KB Authoring application: riched20 6.3.9600 First seen: 2018-02-07
MD5: c3a3e9b641aef75fb189a94608ec9ed9 SHA-1: ee80dcdd2f95926efb0290508785aa1f7b35a4ce SHA-256: cd3d4335fc4afba408fbea91e9f32c671f6429ecd65750b8535dbdeab5516c55
402 Risk Score

Malware Insights

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

The RTF file contains an embedded Equation Editor OLE object that exploits CVE-2017-11882. This exploit is designed to execute arbitrary code, likely downloading and running the payload found at http://tainguyensaefood.com/lok/Desktop.exe. The presence of shellcode candidate regions in the extracted objdata further supports this conclusion.

Heuristics 10

  • 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.
  • 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 CLSID critical RTF_EQUATION_EDITOR
    Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
  • Equation Editor object class critical RTF_OBJCLASS_EQUATION
    Object class 'equation.3' references Equation Editor
  • 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.
  • 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
  • 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://tainguyensaefood.com/lok/Desktop.exe In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000000fe.bin rtf-objdata-decoded RTF \objdata at offset 0xFE 33458 bytes
SHA-256: 27ce1f2218863f7ca034a229c94e46abba62d22d089ad5fb94b492b5606d09e9
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis found candidate code region(s). Indicators: NOP sled