RTF malware analysis — malicious · f90b24cd6cee5036

MALICIOUS

RTF

2.53 MB First seen: 2022-08-09

MD5: df4f9f41e0b8df80d6aa4b2004820f48 SHA-1: d4868378306b98f42989ac0ebb7a3268fdaf84d9 SHA-256: f90b24cd6cee503666e384dfef7c9b828ec98a8de6e2db4c4a8afa2aafe6dcb1

382 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious File T1204.002 Malicious File: User Execution: Malicious Attachment T1059 Command and Scripting Interpreter T1059.003 Command and Scripting Interpreter: Windows Command Shell T1566 Phishing T1566.001 Phishing: Spearphishing Attachment

The RTF document contains an embedded OLE object that exploits CVE-2017-11882 via the Equation Editor. This exploit is designed to drop and execute a second-stage payload, indicated by the presence of a PE header within the hex-encoded object data. The extracted path 'C:\Path\Client.exe' suggests the intended execution location of the dropped payload.

Heuristics 10

Equation Editor activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED

RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger attribution was not recovered.
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.
Split hex Equation Editor ProgID + OLE object critical RTF_EQUATION_EDITOR

RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
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
ClamAV: Rtf.Dropper.Agent-9965975-1 critical CLAMAV_DETECTION

ClamAV detected this file as malware: Rtf.Dropper.Agent-9965975-1
\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.
Large hex data blocks in OLE object high RTF_EXCESSIVE_HEX

RTF contains ~1694KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 2 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object
Suspicious extracted artifact info 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.

Extracted artifacts 2

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off000012c5.bin` `f053b007e937bdb7ec072a3f53464e560e9a3ec53cf167d278743ae80ef956fa`	rtf-objdata-decoded	RTF \objdata at offset 0x12C5	853317 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.41, consistent with packed or encrypted content.
`objdata_01_off001a7ef4.bin` `ffd8c2482cc64da211bcb7ca32c7331bf3796ad5ca2159f697062f334496c915`	rtf-objdata-decoded	RTF \objdata at offset 0x1A7EF4	187349 bytes

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