RTF malware analysis — malicious · fbd9441930655fa3

MALICIOUS

RTF

1.47 MB Authoring application: Riched20 6.3.9600 First seen: 2018-06-14

MD5: a179354cd5f34d5b59b80af1bf174c00 SHA-1: c0b1120d1ec94cd8daf0c998a56da1e0e11d7e26 SHA-256: fbd9441930655fa3131bec0bdd8da47b69a4cb1c922638aab3f81c96dfc93e7a

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 ~1522KB 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	761045 bytes
SHA-256: `fe61b7708fd6335584a625776a91c276b2195b1641cf093bad9e0ac3b8c10f6a`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis found candidate code region(s). Indicators: SC_GETPC_CALL, SC_STR_LOADLIBRARY Static shellcode analysis recovered API/import strings: kernel32.dll, KERNEL32.DLL, LoadLibraryA, GetProcAddress, VirtualAlloc, ExitProcess Carved artifact entropy is 7.89, consistent with packed or encrypted content.
`objdata_01_off00173ae8.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x173AE8	3980 bytes
SHA-256: `e63f5c8cbd1e1d570b46e934261ae1fea2d5d6bd6624a3deb0cf868a3277a4e9`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\cmni.exe &��D$,f-Q��%
`objdata_02_off00175d2e.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x175D2E	3546 bytes
SHA-256: `a4638af5260a10b427f0f799dffd8b6f56a36c98b9271955c5d6c928acadb71b`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\cmni.exe AC

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