Malicious RTF — malware analysis report

Static analysis result for SHA-256 b3f2c1d62c289420…

MALICIOUS

RTF

126.5 KB Created: 2019-09-17 13:59:00 First seen: 2021-06-17
MD5: da05e20748f180b40365d7b0eeb61220 SHA-1: 5f141fce8c2da8a3300154529c3ce788d415957e SHA-256: b3f2c1d62c28942005fae8b826514b5c9f9eff25d2587b9edc625de58b2a6a4d
302 Risk Score

Malware Insights

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

The RTF file contains embedded OLE objects and specifically triggers Equation Editor, indicating exploitation of CVE-2017-11882 and CVE-2017-8759. The presence of shellcode API strings and a shellcode URL within an extracted artifact suggests the file is designed to download and execute a second-stage payload. The document body contains obfuscated text that appears to be an attempt to disguise malicious instructions.

Heuristics 8

  • Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR
    RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
  • 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.
  • 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.
  • 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://schemas.microsoft.com/office/word/2003/wordml In RTF body
    • http://bit.ly/3gcM2I4In RTF body

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off0001ee7a.bin rtf-objdata-decoded RTF \objdata at offset 0x1EE7A 1415 bytes
SHA-256: 068de5ab79d39ff9b7737a18a5e3aaf1ea970aefd03177488dd95b49e5c04236
Detection
ClamAV: No threats found
Obfuscation or payload: likely
Static shellcode analysis recovered URL(s): http://bit.ly/3gcM2I4 Static shellcode analysis found candidate code region(s). Indicators: SC_STR_LOADLIBRARY, SC_STR_URLDOWNLOAD, SC_PEB_ACCESS Static shellcode analysis recovered API/import strings: LoadLibraryA, GetProcAddress, CreateProcessA, URLDownloadToFileA, ExitProcess

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