RTF / .DOC malware analysis — malicious · 8b3d9d3f59843c56

MALICIOUS

RTF / .DOC

1.84 MB First seen: 2023-02-21

MD5: 5d49d66c63fe0341b876eea066d8f67c SHA-1: 35313aa0ec7c944a518ff34b62755cbfe2d17f78 SHA-256: 8b3d9d3f59843c560f8eefefaa26f2d26b4b85480c81198d12ccbd067f8886d4

262 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1027 Obfuscated Files or Information

The RTF document contains an OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is used to execute a decoded PE payload, indicating a likely initial access vector for further malicious activity. The presence of a large, high-entropy objdata section further supports the hiding of a malicious payload.

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 ~1925KB 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_off00000079.bin` `257d87e6f41418e059193d1f61916a92cc269c34f303c55677af50f7b20658b1`	rtf-objdata-decoded	RTF \objdata at offset 0x79	963067 bytes
Detection ClamAV: No threats found Obfuscation or payload: likely Carved artifact entropy is 8.00, consistent with packed or encrypted content.

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