RTF malware analysis — malicious · c5b948e60d40f45f

MALICIOUS

RTF

4.79 MB Created: 2024-04-03 08:46:00 First seen: 2025-04-08

MD5: 943d5ed6c8a8ded0656ae6d676a4a340 SHA-1: 3bbfef4619bf03df4283745617abd790cd15c426 SHA-256: c5b948e60d40f45f95b8007fa36969283edd529a65c67d7a8db74bc111b8dbc8

222 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF file contains multiple indicators of exploitation for CVE-2017-11882, including OLE object data and specific Equation Editor references. The ".objupdate" directive suggests automatic activation of the embedded OLE object, which is designed to execute malicious code. The large amount of hex-encoded data within the OLE object likely conceals a second-stage payload, intended to be downloaded and executed.

Heuristics 7

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.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~2825KB of hex-encoded data inside \objdata sections — may hide a payload
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
Embedded URL info EMBEDDED_URL

One or more URLs were extracted from the document. The URL itself is not a detection — see the per-URL labels for which channel (macro, JS, link annotation, document body, ...) reached each URL.

URL http://schemas.microsoft.com/office/word/2003/wordml

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00003a12.bin` `bf370e47550b0ac31e7dc875c0a7407e6b52ef6302221214ddfb0cd0f0eaab1d`	rtf-objdata-decoded	RTF \objdata at offset 0x3A12	1425001 bytes
`objdata_01_off002c6737.bin` `cfdb4a077c5f246e92e6322395cebc5a3dcf8a28c92ec8882aadb5231c9a8a69`	rtf-objdata-decoded	RTF \objdata at offset 0x2C6737	584266 bytes

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