Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 d6c1c2c9b1c34a82…

MALICIOUS

RTF / .DOC

29.8 KB
MD5: 4f272fdc3b700db5f177238fa35c36d1 SHA-1: a84e9d00f1c4f553e7ff362de09ffedd95f3812f SHA-256: d6c1c2c9b1c34a828b5c0caeab60fff25aa0cadc2e833175c721b0566d2ea823
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1059.001 PowerShell T1204.002 Malicious File

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability in Microsoft Equation Editor. This is indicated by the RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristic firings. The objupdate directive forces the OLE object to activate, leading to code execution. The decoded object's class name, 'equAtIon.3', is a strong indicator of this specific exploit. The likely intent is to download and execute a secondary payload, a common tactic for this vulnerability.

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 1

Files carved from inside the sample during analysis.

FilenameKindSourceSize
objdata_00_off00001e6d.bin
f7d885d4640beb529bad11c238933422fb9cddc67d548d2359d5e95358f19dbb		 rtf-objdata-decoded RTF \objdata at offset 0x1E6D 2144 bytes

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