Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 81031b5f43806143…

MALICIOUS

RTF / .DOC

2.21 MB
MD5: 82d21db046510d3102df769a23b12048 SHA-1: 7ea166f1cefa324a161f2f28b04039ad58d1012b SHA-256: 81031b5f4380614310f887bc4f2497b7fc019089412f129bd8272fa7ba974ae6
180 Risk Score

Malware Insights

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

The RTF document contains multiple indicators of malicious activity, including embedded OLE objects and specific heuristics pointing to the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This exploit is commonly used to achieve arbitrary code execution, likely to download and run a secondary payload.

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.
  • \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
  • Embedded OLE object medium RTF_OBJEMB
    RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001202.bin
4eb44be67f27e7a933895ca19c4fc3c3684ceb7dfcecf2b06f9b84772788c6fa		 rtf-objdata-decoded RTF \objdata at offset 0x1202 27057 bytes
objdata_01_off0001c923.bin
fe43efbadd674765243cb2580d9955cd54bcbea3b2eb0d6d648fe532cb7ef883		 rtf-objdata-decoded RTF \objdata at offset 0x1C923 476202 bytes

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