Malicious RTF — malware analysis report

Static analysis result for SHA-256 f890106085bdb1ff…

MALICIOUS

RTF

45.3 KB First seen: 2022-12-28
MD5: fcb2dd8e27e48f906fa6319e3bfe8c10 SHA-1: dc5b154907b121cb0c288d4357f33f0185f03c01 SHA-256: f890106085bdb1ff9912b85501b7dce6ef7981bde33d00654b9ead07e046826d
180 Risk Score

Malware Insights

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

The RTF file contains an embedded OLE object that exploits the CVE-2017-11882 vulnerability in Microsoft Equation Editor. The presence of \objupdate and the specific ProgID 'EQUaTIOn.3' strongly indicate this exploit is intended to activate the embedded object and execute arbitrary code. This is a common technique for delivering secondary payloads, although no specific payload details were extracted from this sample.

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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