RTF / .DOC malware analysis — malicious · 5c7ab4967fe48f0c

MALICIOUS

RTF / .DOC

1.45 MB First seen: 2023-03-01

MD5: 33c982965f55ba0ace8afff081a1dd4b SHA-1: 3f99fc3f9618c00e75d512a369d1935fa7680e7e SHA-256: 5c7ab4967fe48f0caa3c207e722d2869735304df4d217b0a63ae958b77ae04d8

262 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1566 Phishing T1204.002 Malicious File T1027 Obfuscated Files or Information

The sample is an RTF document that leverages the Equation Editor vulnerability (CVE-2017-11882) to execute a payload. The presence of OLE object data and specific heuristics related to Equation Editor strongly indicate this exploit. The embedded payload, identified as a PE file, is likely a secondary stage designed to further compromise the system.

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 ~1514KB 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_off00000076.bin` `8c8a8153dbf6634b193bf3ddc01d6d7aee66889ac9be6365506891c8bc1dd3fe`	rtf-objdata-decoded	RTF \objdata at offset 0x76	757549 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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