RTF malware analysis — malicious · 8b58f24fc69498e9

MALICIOUS

RTF

1.11 MB First seen: 2023-02-06

MD5: d1656ae31e8e6f82bc6c31174d1e0edd SHA-1: 174d00f40bc5de13e4558a04c8199e3847b6d27f SHA-256: 8b58f24fc69498e9cb21333bfd0f9054aae1a43f5f477ccfaf89555e4b5769ba

262 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF file contains an OLE object specifically identified as related to CVE-2017-11882, which is a known vulnerability in Microsoft Equation Editor. The heuristic firings indicate that this object contains a decoded payload and a PE file, suggesting it's used to deliver a secondary malicious artifact. The large amount of hex-encoded data within the OLE object further supports the hiding of an embedded 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 ~1160KB 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_off0000007c.bin` `9cb3fb80b3eb7a5d59b5dd9023539ca96b2226e43d4a39d945b96889e6c21ed5`	rtf-objdata-decoded	RTF \objdata at offset 0x7C	580672 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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