RTF malware analysis — malicious · cf095c50713831f8

MALICIOUS

RTF

9.5 KB First seen: 2023-01-10

MD5: 6a83e53c7a33121c90b80ebb440d0c59 SHA-1: 2024e397631323f07e889aaf5848314d064fc3a9 SHA-256: cf095c50713831f876f8aa0b28c1ead3330d821222ae879eb0a49c15c25e62fe

180 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF file contains an embedded OLE object specifically targeting the Equation Editor, which is indicative of the CVE-2017-11882 vulnerability. The presence of RTF_EQUATION_EDITOR and CVE_2017_11882_ACTIVATION_RELATED heuristics strongly suggests exploitation of this known vulnerability. The ".objupdate" directive further forces OLE activation, confirming the exploit attempt. The document body is heavily obfuscated and unreadable, providing no direct clues to the payload's intent, but the exploit itself is the primary indicator of malicious activity.

Heuristics 5

Obfuscated Equation Editor ProgID + activation critical CVE related RTF_EQUATION_EDITOR

RTF decodes to an Equation.3 ProgID from top-level \objdata hex after nested RTF junk groups are ignored, and the document also contains \objemb plus \objupdate activation. This is an obfuscated Equation Editor exploit surface associated with CVE-2017-11882 / CVE-2018-0802 families, but no exact malformed MTEF CVE primitive was recovered from this object.
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.
\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.

Filename	Kind	Source	Size
`objdata_00_off00001ab3.bin` `ae9ee920635286adea32479b9566721d6f88b0023c9da015120b07234c26505c`	rtf-objdata-decoded	RTF \objdata at offset 0x1AB3	1421 bytes

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