RTF malware analysis — malicious · 2b23e07e14d6dc53

MALICIOUS

RTF

1.30 MB Authoring application: Riched20 6.3.9600 First seen: 2019-09-30

MD5: 7c159e18e6373364f7fbe1cada189fbf SHA-1: 641712aa4f523ac1f3f85bce17ab98d629d5eeee SHA-256: 2b23e07e14d6dc53c41bdf4e0cccc0afa312a107792c99283a2769cf78ff2f34

560 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains multiple indicators of malicious activity, most critically the exploitation of CVE-2017-11882 via the Equation Editor. This vulnerability allows for arbitrary code execution when the document is opened. The presence of embedded OLE objects and large hex-encoded data blocks further suggests the hiding of a malicious payload, likely a second-stage executable.

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.
Composite Moniker in RTF OLE object high CVE related RTF_COMPOSITE_MONIKER_RELATED

RTF contains Composite Moniker CLSID in OLE object context, but no nearby scriptlet/SCT payload was confirmed. Treat as related moniker attack-surface evidence rather than proof of CVE-2017-8570 exploitation.
ClamAV: Win.Malware.Noon-6721822-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Malware.Noon-6721822-0
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 ~1343KB 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	671975 bytes
SHA-256: `640d6344ff2b54bd907a5df56ea220c4496ce423ac124ab1731a49b52d681470`
Detection ClamAV: Win.Malware.Noon-6721822-0 Obfuscation or payload: unlikely
`objdata_01_off0014830c.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x14830C	3980 bytes
SHA-256: `9432102025fce6e48feb501e581cab5ada8e89c1486ece2c1444b6c9aae0142d`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\update.exe &��D$,f-Q��%
`objdata_02_off0014a552.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x14A552	3546 bytes
SHA-256: `5115c929c9c4085a837c69854df27c796ffd4c8dfe80fdc32260feecd36cbd92`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\update.exe AC

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