RTF / .DOC malware analysis — malicious · 55be2ab6bcd32fe4

MALICIOUS

RTF / .DOC

1.85 MB First seen: 2023-02-13

MD5: 47d4d1036aa1bd03159f548c5f82b8de SHA-1: 39867331fd7959d8f04bdcfdc57fd5764abe59b0 SHA-256: 55be2ab6bcd32fe49927c60d0b463572ffd0eabd6f55a28354df2924be9ea7d2

222 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains an embedded OLE object with high entropy, indicative of a hidden payload. Critical heuristics confirm the presence of a decoded Equation Editor payload related to CVE-2017-11882, which is known to be used for arbitrary code execution. The file likely serves as a dropper for a secondary malicious payload.

Heuristics 6

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.
\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 ~1935KB 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_off00000075.bin` `396817cf1b6c527cb5c9a552319f7491d01a5ddd30c51350b4dd51429b039a47`	rtf-objdata-decoded	RTF \objdata at offset 0x75	967867 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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