Ponystealer RTF malware analysis — malicious · 151f40b2f9c19e38

MALICIOUS

RTF

1.74 MB Authoring application: Riched20 6.3.9600 First seen: 2019-03-10

MD5: 829f296383564c6cef70a0860bffe718 SHA-1: 2ca8404ba2c1d4d829cd844e123930350ac60316 SHA-256: 151f40b2f9c19e38f4985027bd89a013aa12ff313068cfe8b2fd773f652f6cd9

520 Risk Score

Malware Insights

Ponystealer · confidence 95%

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains embedded OLE objects, specifically exploiting the CVE-2017-11882 vulnerability in Equation Editor. This vulnerability allows for the execution of arbitrary code, and the presence of PE headers within the hex data strongly suggests a payload is being delivered. ClamAV detections confirm this, identifying the file as Win.Dropper.Ponystealer-7398513-0, indicating a stealer malware family.

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: Win.Dropper.Ponystealer-7398513-0 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Win.Dropper.Ponystealer-7398513-0
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 ~1802KB 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	901333 bytes
SHA-256: `d681ab7d0005e3aa499d523e1d5f7a51a8e4a3d1d10060263bb05b7041b0c730`
Detection ClamAV: Win.Dropper.Ponystealer-7398513-0 Obfuscation or payload: likely Carved artifact entropy is 7.45, consistent with packed or encrypted content.
`objdata_01_off001b82e8.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x1B82E8	3980 bytes
SHA-256: `131813d3ee15cbc62797d7e9225ce3fe7952f51dfa0ff9549823664cf27ff4d0`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\jona.exe &��D$,f-Q��%
`objdata_02_off001ba52e.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x1BA52E	3546 bytes
SHA-256: `3efd27419e7accd780d3e7fdd57a0b3f511e5044b1b29b930e2d5b2e55896ff6`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): cmd.exe /c%tmp%\jona.exe AC

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