Malicious RTF / .DOC — malware analysis report

Static analysis result for SHA-256 629e741cc3b0fbc2…

MALICIOUS

RTF / .DOC

11.5 KB First seen: 2022-10-25
MD5: 2ea85ee5dfd1c03ef493fd5391ec72d9 SHA-1: bfb2a08a8fd45768ad1bdff7d152844f2c47a1b3 SHA-256: 629e741cc3b0fbc23d8456e818f9cdf209bc5665585f1b8c5614f29adce1cdb0
180 Risk Score

Malware Insights

MITRE ATT&CK
T1204 Malicious Link T1566 Phishing T1204.002 Malicious File T1059.001 PowerShell T1027 Obfuscated Files or Information

The RTF document contains an embedded OLE object that exploits CVE-2017-11882, a known vulnerability in Microsoft Equation Editor. The critical heuristic firing for RTF_EQUATION_EDITOR and the high confidence firing for CVE_2017_11882_ACTIVATION_RELATED strongly indicate this exploit. The ".objupdate" directive forces the activation of the embedded object, leading to arbitrary code execution. The specific class name 'eQuAtIOn.3' is also a strong indicator.

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 1 \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_off000017fe.bin
badacca5ff3204267e82e33d575fc6355b2a178b86510792bfbcebc05609e5e8		 rtf-objdata-decoded RTF \objdata at offset 0x17FE 1518 bytes

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