RTF malware analysis — malicious · 6766fad276a44177

MALICIOUS

RTF

1.84 MB Authoring application: Riched20 6.3.9600 First seen: 2018-05-18

MD5: 87d66485084be3b3ca51fdefca973237 SHA-1: de2980357daf06573e97d0dfdf52982d8b7d6288 SHA-256: 6766fad276a4417756c5300556153e466920ed6fe9c57225d0ffc11328274887

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 ~1909KB 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	954572 bytes
SHA-256: `1fbe10c21e3e042347045fe3c09cb63656a261431c728cf525025d7cf99afb08`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.
`objdata_01_off001d22d6.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x1D22D6	3980 bytes
SHA-256: `ee292f7030fd5c0cd583d3c70ce349220f055ea71f999b0098354ee7995130d5`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\jj1.exe &��D$,f-Q��%
`objdata_02_off001d451c.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x1D451C	3546 bytes
SHA-256: `dac162332010c3582bef89d65bb41ffdd7d167bc6fb8ee27b87c8ddaa865713d`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\jj1.exe AC

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