Malicious RTF — malware analysis report

Static analysis result for SHA-256 04bd9194b93c6bd7…

MALICIOUS

RTF

36.6 KB
MD5: 1ca77bf28a6c972883350a1de484ab7f SHA-1: 65185838f0988c97ee6f3c691ff3edf0c8d96550 SHA-256: 04bd9194b93c6bd779d9506b6e0fa01a57d09e34abbb2a94563206f621611a73
200 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. This exploit allows for the execution of arbitrary code, likely to download and run a secondary payload. The presence of RTF_OBJDATA, RTF_OBJAUTLINK, RTF_EQUATION_EDITOR, and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates this attack vector.

Heuristics 5

  • 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.
  • Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR
    RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
  • Automatically linked OLE object high RTF_OBJAUTLINK
    RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
  • \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 2 \objdata section(s) — embedded OLE objects

Extracted artifacts 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off000010ac.bin
a04be15d2f390186fdcca570f1c291475156e99fd80063c5d0767eef3898215b		 rtf-objdata-decoded RTF \objdata at offset 0x10AC 1524 bytes

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