RTF / .DOC malware analysis — malicious · 941f029da26d98f5

MALICIOUS

RTF / .DOC

1.53 MB First seen: 2023-06-19

MD5: 6331c9fe72be8b908696264f2d18413f SHA-1: e49ea0059ca2f6b663eb9639a7e275956f6f44da SHA-256: 941f029da26d98f5005bb47b1c5ea697ef97ec2e179b106bd0b40dc52ba32583

262 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1559.001 Component Object Model and Distributed Component Object Model

The RTF document contains a malformed OLE object specifically targeting the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is leveraged to execute a decoded PE payload, indicated by the high entropy and MZ offset found within the object data. The primary attack vector is the exploitation of this known Microsoft Office vulnerability.

Heuristics 7

Equation Editor OLE1 native payload — CVE-2017-11882 related critical CVE related CVE_2017_11882_RELATED

RTF decodes to an OLE1 Equation.3 embedded object whose native data is large and payload-like, and \objupdate requests automatic activation. This is the delivery shape used by Equation Editor RCE documents such as CVE-2017-11882/CVE-2018-0802, but the malformed MTEF record needed for exact attribution was not recovered.
Decoded Equation Editor payload + PE critical RTF_EQUATION_EDITOR

RTF decodes to an Equation Editor ProgID adjacent to OLE activation and the same decoded object stream contains embedded PE bytes. This matches the Equation Editor exploit surface used by CVE-2017-11882 / CVE-2018-0802 documents, while requiring payload evidence to avoid flagging benign Equation references.
Automatically linked OLE object high RTF_OBJAUTLINK

RTF contains \objautlink — an automatically linked OLE object surface that can be updated or activated when Word opens the document.
\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 ~1602KB of hex-encoded data inside \objdata sections — may hide a payload
OLE object data medium RTF_OBJDATA

RTF contains 1 \objdata section(s) — embedded OLE objects
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 1

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off0000008d.bin` `01d46e9146cbc13eb54af5528d75fa1f3c5ed54be0d68c0c8d9b51a7b9efb512`	rtf-objdata-decoded	RTF \objdata at offset 0x8D	801053 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 7.99, consistent with packed or encrypted content.

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