RTF / .DOC malware analysis — malicious · 4659186cccfb9bb9

MALICIOUS

RTF / .DOC

32.7 KB First seen: 2023-01-10

MD5: ef93fa6845a7f03d2809cf03a14e0c39 SHA-1: d2e4d2a05c854705fa43d40b5db4ff414b28a586 SHA-256: 4659186cccfb9bb9cf85deb8456bd9dcc4a55a5efb81d5498403c795eae490f9

220 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1559 Component Object Model Hijacking T1559.001 Component Object Model Hijacking: Component Object Model T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic

The sample is an RTF document that contains an embedded OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_OBJDATA, RTF_OBJAUTLINK, RTF_EQUATION_EDITOR, and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly indicates exploitation of this known vulnerability. The SE_ENABLE_LURE heuristic confirms that the document employs a social engineering tactic to prompt the user to enable editing, which is necessary to trigger the exploit.

Heuristics 6

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.
Automatically linked OLE object high RTF_OBJAUTLINK

RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
\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
Macro/content-enable lure medium SE_ENABLE_LURE

Document instructs the user to enable macros or editing — a common technique used by malware droppers to bypass Office macro security settings

Extracted artifacts 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00004105.bin` `5558ac871511fee20cf3a9a4d1ad9630bf57aa574c4d637656d38e961a14dba8`	rtf-objdata-decoded	RTF \objdata at offset 0x4105	1899 bytes

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