Malicious RTF — malware analysis report

Static analysis result for SHA-256 25561fad1b229895…

MALICIOUS

RTF

40.7 KB
MD5: 2022dc66acd507f82b20c8baffed02aa SHA-1: e0b3cd592e3f63ccae20b3171cfa5412c8c7e827 SHA-256: 25561fad1b22989533c20ac2cb1ea116d19a3900052541346d5abb9262a95ab3
180 Risk Score

Malware Insights

MITRE ATT&CK
T1203 Exploitation for Client Execution T1566.001 Phishing: Spearphishing Attachment T1068 T1203

The sample is an RTF document containing an embedded Equation.3 object and the \objupdate control word, which is a classic signature of CVE-2017-11882 or CVE-2018-0802. The lack of a recovered MTEF stream or scripts allows for a high confidence in the exploit delivery mechanism, but prevents specific family attribution.

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_off0000091c.bin
99577784d162106c5091ddd78f1f59480abe100f9698ad951af939a13798f7ee		 rtf-objdata-decoded RTF \objdata at offset 0x91C 1698 bytes

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