Win.Dropper.Ursu-6848742-0 RTF malware analysis — malicious · 676135663b42ad86

MALICIOUS

RTF

1.18 MB Authoring application: Riched20 6.3.9600 First seen: 2020-02-04

MD5: 1e48e8c2a4ee93262dccb6d8f229d2c2 SHA-1: 71aca6fd51d5ad02917842c6501d40dad6bb69d8 SHA-256: 676135663b42ad86c4d8dde72c263bb828b88af8954bd65ba00b41be27ed8be9

522 Risk Score

Malware Insights

Win.Dropper.Ursu-6848742-0 · confidence 95%

MITRE ATT&CK

T1203 Exploitation for Client Execution T1059.001 PowerShell

The RTF file contains an embedded OLE object that exploits CVE-2017-11882 in Equation Editor. This exploit likely facilitates the execution of a secondary payload, as indicated by the detection of shellcode candidate regions and command strings within extracted artifacts. The ClamAV detection name 'Win.Dropper.Ursu-6848742-0' further supports the dropper functionality.

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.Dropper.Ursu-6848742-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Dropper.Ursu-6848742-0
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 ~1220KB 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 http://www.usertrust.com1 In RTF body
- http://ocsp.usertrust.com0In RTF body
- http://crl.usertrust.com/UTN-USERFirst-Object.crl05In 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	610335 bytes
SHA-256: `962dfd3ac662be5045cb033e3eea55d1af185fe1ba83f3ed17d1bb16eff28401`
Detection ClamAV: Win.Dropper.Ursu-6848742-0 Obfuscation or payload: likely Static shellcode analysis found candidate code region(s). Indicators: SC_PEB_ACCESS
`objdata_01_off0012a17c.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x12A17C	3980 bytes
SHA-256: `30c704d954ed2f2decda1b1cc8515253370822d3b73b49210716f783d14f639d`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\dllmon.exe &��D$,f-Q��%
`objdata_02_off0012c3c2.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x12C3C2	3546 bytes
SHA-256: `9cac8e98cb4407f3cb52439fee49b997f07a50092dc5c731b5d45ca03ba80b38`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\dllmon.exe AC

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