RTF malware analysis — malicious · d0e8f0d8d1f9c67f

MALICIOUS

RTF

1.12 MB Authoring application: Riched20 6.3.9600 First seen: 2019-05-31

MD5: a777d7d4b6705c728c6b32f108d0e550 SHA-1: ff889050700e07856da204691c5279dc9dd60db9 SHA-256: d0e8f0d8d1f9c67fff82170ee2b0c9fe1bb9967f348ff1176176f5fe3fd1b818

500 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE objects, specifically exploiting the Equation Editor vulnerability (CVE-2017-11882). This vulnerability allows for arbitrary code execution when the embedded object is activated. The presence of PE headers within the hex-encoded data further suggests a malicious payload is hidden within the object. The file is classified as malicious due to this exploit.

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: 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 ~1156KB 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	578261 bytes
SHA-256: `66e1cde50976ee95b3f4e3219e62a458e27c002e9b927cc514003a7ca6f3d134`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis found candidate code region(s). Indicators: SC_PUSH_STRING, SC_STR_VIRTUALPROTECT Static shellcode analysis recovered API/import strings: kernel32.dll, KERNEL32.DLL, VirtualProtect Carved artifact entropy is 7.55, consistent with packed or encrypted content.
`objdata_01_off0011a6e8.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x11A6E8	3980 bytes
SHA-256: `f6a81f8be332e34c8d36ea9f961a2a044b0feb685e15ab11a17c6987849d2579`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\hhhh.exe &��D$,f-Q��%
`objdata_02_off0011c92e.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x11C92E	3546 bytes
SHA-256: `47e63c006eb81ff94d98dab80b056f719ae51297def7f0017cf8c6718d1f684f`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\hhhh.exe AC

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