RTF malware analysis — malicious · 18bd3d93b585d173

MALICIOUS

RTF

615.9 KB Authoring application: Riched20 6.3.9600 First seen: 2019-11-20

MD5: 61a9707b443d7b31cf84591e6606517a SHA-1: 08de04f8665284baef299fc06d37c8fe4920b034 SHA-256: 18bd3d93b585d173f327d931f1141f6245f0fafd95046e99c9ef543eceb165f2

420 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The sample is an RTF document containing embedded OLE objects, specifically triggering the CVE-2017-11882 vulnerability in Equation Editor. This exploit allows for the execution of arbitrary code, likely to download and run a secondary payload. The presence of PE headers in hex data and suspicious extracted artifacts further supports this conclusion.

Heuristics 10

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
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	306892 bytes
SHA-256: `4e1e4b4fb3beee9cd62c6f6b9bda14416e594dd70dda1c5831d36d3fb1ed1075`
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.97, consistent with packed or encrypted content.
`objdata_01_off00095ed6.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x95ED6	3980 bytes
SHA-256: `07b1349d025c079ce3a51e68185042029ac1b72655af33696ad027058c460773`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\ggg.exe &��D$,f-Q��%
`objdata_02_off0009811c.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x9811C	3546 bytes
SHA-256: `4a68f6bbeb359b04164e9dae294eab843b1a8183616f8a26a02e57134afd6651`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\ggg.exe AC

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