RTF malware analysis — malicious · a5c58121720ec831

MALICIOUS

RTF

1.11 MB Authoring application: Riched20 6.3.9600 First seen: 2018-12-09

MD5: 85a8bfef37a9492def1376c096d89f7a SHA-1: 8540c2927305af585ce90b7ce9d6d4f0d8d04773 SHA-256: a5c58121720ec8315aea0a20c1039b270e403da5e925c6843a04f55210b5f81e

522 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE objects and triggers critical heuristics for CVE-2017-11882, indicating exploitation of the Equation Editor vulnerability. ClamAV detections on the main file and extracted artifacts further confirm its malicious nature, identifying it as Win.Malware.Zbot-7352300-0. The presence of a PE header within hex data suggests the embedded object is a loader for a secondary payload.

Heuristics 12

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: Win.Malware.Zbot-7352300-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Malware.Zbot-7352300-0
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 ~1151KB 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.
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 https://www.samsung.com/us/0 In RTF body
- https://www.samsung.com/us/0�In RTF body
- https://www.samsung.com/us/In RTF body

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	575972 bytes
SHA-256: `6a1f485e4440c55074b2941948cf34de1d50ff6c17c9564e8633ab0225701765`
Detection ClamAV: Win.Malware.Zbot-7352300-0 Obfuscation or payload: likely Carved artifact entropy is 7.45, consistent with packed or encrypted content.
`objdata_01_off00119506.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x119506	3980 bytes
SHA-256: `1103608a6116451254c13c56c6074d9fb0ef8e4eb9055612a32b6cd24d1a5ca8`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\Adobereader.exe &��D$,f-Q��%
`objdata_02_off0011b74c.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x11B74C	3546 bytes
SHA-256: `65878affb8ae118188bba25e3828ce6ca7d2e644e96fa49ece45dc3a1afeeaf8`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\Adobereader.exe AC

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