RTF malware analysis — malicious · 4f7d97bdfed080ea

MALICIOUS

RTF

1.04 MB First seen: 2022-12-28

MD5: 91421f2c296405c446e641a17d8b89c8 SHA-1: 3dcf9d1d671d312cce1095a3c6a16bccd66a3deb SHA-256: 4f7d97bdfed080ea6bc93aae9ed0d058800e506a53a7639ccd4dee0bafedcceb

180 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF document contains embedded OLE objects, specifically identified as related to Equation Editor and CVE-2017-11882. The presence of \objupdate and the Equation Editor ProgID strongly indicate an attempt to exploit this known vulnerability for client execution. The document body appears to contain obfuscated JavaScript-like code, likely intended to facilitate the exploit, but its exact function is unclear due to truncation. The primary attack vector is likely spearphishing attachment.

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 2 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000011e1.bin` `397bec704394addad0e1ae2369c44b2a01404d7536c298fc4b626fb30cd56d15`	rtf-objdata-decoded	RTF \objdata at offset 0x11E1	20273 bytes
`objdata_01_off0001274d.bin` `a6f253d6bbd0460ac77e10ef1bc8f05800fa5562b3652b8ea10ed15d9e3c5eda`	rtf-objdata-decoded	RTF \objdata at offset 0x1274D	246442 bytes

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