RTF malware analysis — malicious · cf1b4d19fdac7146

MALICIOUS

RTF

1.65 MB Authoring application: Riched20 6.3.9600 First seen: 2019-01-25

MD5: c1aebdcfa39c596c31763c107fef2b96 SHA-1: 608701178f1407304244224516d656b656512a69 SHA-256: cf1b4d19fdac71469c58c86bfb71f40404607311af0b425c16ee8b28c3b3e6b6

460 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of exploitation, most critically the CVE-2017-11882 heuristic firing, which points to the Equation Editor vulnerability. The presence of embedded OLE objects and large hex-encoded data blocks further suggests the file is designed to deliver a malicious payload. ClamAV also detected this file as Rtf.Exploit.CVE_2017_11882-6584355-1.

Heuristics 11

Equation Editor CLSID critical CVE likely RTF_EQUATION_EDITOR

Equation Editor OLE CLSID found inside an OLE object — exploited by CVE-2017-11882 / CVE-2018-0802 / CVE-2018-0798
CVE-2017-11882 — Equation Editor FONT record overflow critical CVE likely CVE_2017_11882

Equation Editor MTEF contains an overlong FONT typeface field, the vulnerable copy primitive for CVE-2017-11882. This is stronger evidence than the Equation Editor CLSID alone because it identifies the malformed record that drives code execution in EQNEDT32.EXE.
ClamAV: Rtf.Exploit.CVE_2017_11882-6584355-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Exploit.CVE_2017_11882-6584355-1
PE header (with DOS stub) in hex data critical RTF_MZ_HEX

Hex-encoded PE (MZ + DOS stub) found inside RTF — likely an embedded executable payload
\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.
Package object class high RTF_OBJCLASS_PACKAGE

OLE Package object — can wrap arbitrary files
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1709KB of hex-encoded data inside \objdata sections — may hide a payload
Suspicious extracted artifact high EXTRACTED_FILE_STATIC_TRIAGE

One or more files extracted from inside this sample matched static suspicious-content checks such as script obfuscation, encoded payload blobs, packed data, or execution/download terms.
OLE object data medium RTF_OBJDATA

RTF contains 3 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
OlePres presentation stream in RTF OLE object medium RTF_OLEPRES_STREAM

RTF contains an embedded OLE object with an OlePres presentation stream. OlePres is an OLE presentation marker and is not enough on its own to identify CVE-2025-21298.

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000000ef.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xEF	854723 bytes
SHA-256: `a5faaa4c984be4074a1ba2e964323c64bd19cd3b83496d2be9d92fb0d9858e42`
`objdata_01_off001a16c4.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x1A16C4	3980 bytes
SHA-256: `ac8a7e13ba64535099d5ad54b250020737ccb36b17d1ba3fbf46c666ade5d49c`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\22.exe &��D$,f-Q��%
`objdata_02_off001a390a.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x1A390A	3546 bytes
SHA-256: `2c15936c0c88d1528de427474b7ed42e81726f3548a0ea8bcea349ff48eed841`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\22.exe AC

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