RTF / .DOC malware analysis — malicious · ab9d7fab959ed3ea

MALICIOUS

RTF / .DOC

31.6 KB First seen: 2023-02-15

MD5: b323b73ee6ccc8f994e7d5e06ddf4329 SHA-1: afd056cdc6ee8ffbfcf5f416e0380fc7cdf602ae SHA-256: ab9d7fab959ed3ead4cac875a03f1eaa576999fcec0100e1b9ca6b1e2a2d2b35

220 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The sample is an RTF document that contains OLE object data, specifically targeting the Equation Editor vulnerability (CVE-2017-11882). The presence of RTF_OBJAUTLINK and RTF_OBJUPDATE heuristics indicates an attempt to automatically activate the embedded object. The SE_ENABLE_LURE heuristic confirms that the document likely contains a prompt to enable editing or macros, a common social engineering tactic to bypass security measures.

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_off00004bcf.bin` `4d00d115d736328c895f3bd840cabb38a7c9e79ab0b992dd6c5b775a649867ff`	rtf-objdata-decoded	RTF \objdata at offset 0x4BCF	1642 bytes

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