RTF malware analysis — malicious · f63765f4fa17eb57

MALICIOUS

RTF

1.30 MB First seen: 2023-07-17

MD5: e9c1a95a63c907f7cdb1eb640cdd285c SHA-1: f617f2a7af5ec5cf069e4089503230427bd2135b SHA-256: f63765f4fa17eb57dc81bbe7b4da69dcb0e89785f8a7ba5d68d0877bd37fe04a

222 Risk Score

Malware Insights

MITRE ATT&CK

T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF file contains an OLE object that exploits the Equation Editor vulnerability (CVE-2017-11882). This vulnerability is known to be used to embed and execute arbitrary code, typically leading to the download and execution of a second-stage payload. The presence of a large, high-entropy OLE object strongly indicates the embedding of a malicious executable.

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 ~1359KB 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_off0000009f.bin` `a383d06a5e98c6d4dd0e613b7ea446969427adf39f20ad2f38685fe36f37b26c`	rtf-objdata-decoded	RTF \objdata at offset 0x9F	679638 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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