RTF / .DOC malware analysis — malicious · 0558f8b1e34ddf19

MALICIOUS

RTF / .DOC

29.9 KB First seen: 2022-11-14

MD5: 1eddf9f4f13b7a31996916bfcb09a367 SHA-1: c8e88db4b1a37db3d6f416461591551c4c1cefe4 SHA-256: 0558f8b1e34ddf19fcb4ff32a0632a347090168c90e1689d071e82043863fc62

220 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1204.002 Malicious Link: Malicious File T1059 Command and Scripting Interpreter T1059.005 Command and Scripting Interpreter: Visual Basic T1566 Phishing T1566.001 Phishing: Spearphishing Attachment T1566.002 Phishing: Spearphishing Link

The sample is an RTF document that leverages the CVE-2017-11882 vulnerability in the Equation Editor component. The presence of OLE object data and specific heuristics like RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED strongly indicate exploitation of this known vulnerability. The document also contains a lure to enable editing, common for macro-based malware delivery.

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_off000058fc.bin` `a6e8508c8eaa5017ef96f67a57071a30f93b5c768ad19717c6855ee3de1e86cf`	rtf-objdata-decoded	RTF \objdata at offset 0x58FC	1723 bytes

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