Malicious RTF — malware analysis report

Static analysis result for SHA-256 671ec8ee4d627756…

MALICIOUS

RTF

45.2 KB
MD5: 54399e3ebd25cbf8b8a14de28318b1c1 SHA-1: 0f1a005cc9a38a4f093eb283e8caf95a4626418a SHA-256: 671ec8ee4d62775684aa1f8eef39ce609d0896217f3e7e9d6dc5cf8359810612
180 Risk Score

Malware Insights

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

The RTF document contains an embedded OLE object with a split hex Equation Editor ProgID, indicative of CVE-2017-11882 exploitation. The ".objupdate" directive forces OLE activation, leading to client-side execution of arbitrary code. No specific family could be identified, but the exploit method is clear.

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_off00001ef9.bin
834bc768eeef9c6f2c9d0b1fab8f5fd6af7c8c7c44be1279d5a3156bc856a4d2		 rtf-objdata-decoded RTF \objdata at offset 0x1EF9 1833 bytes

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