Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 86d79be603142ed0…

MALICIOUS

RTF / .DOC

1.20 MB First seen: 2022-10-12
MD5: 0f6795e67ddd354f1bbfccd38ef4a310 SHA-1: 7ea97395d4611a9e08ece3995c6060c9250d5d68 SHA-256: 86d79be603142ed01bae4fe9f890123da7135f6aa274d585432bc383eb2c405c
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1204.002 Malicious File T1059 Command and Scripting Interpreter T1566 Phishing T1566.001 Spearphishing Attachment

The RTF document contains an embedded OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). This exploit is designed to execute arbitrary code, likely a malicious script, as indicated by the 'Equation Editor activation' and 'RTF_EQUATION_EDITOR' heuristics. The embedded object's class is identified as 'Equation.3', which is a strong indicator of this specific exploit.

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_off000012b8.bin
35a82acd02fb034bacd2066e377060df7be578610b2d217d1fa19453f63947f1		 rtf-objdata-decoded RTF \objdata at offset 0x12B8 156203 bytes
objdata_01_off000538a6.bin
83d5bb1839df37f7a8edeb2ba75fa5745f7c4929c4a96b9f25135a1ffd60f649		 rtf-objdata-decoded RTF \objdata at offset 0x538A6 187615 bytes

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