RTF malware analysis — malicious · da71aef704b13b59

MALICIOUS

RTF

1.07 MB First seen: 2023-02-14

MD5: ac29db412ed96f5cad7cc118413a8f3e SHA-1: a1d38d8ddef400dad25e8d8860b7043dee7ef443 SHA-256: da71aef704b13b59e79c0c252721ceb3ced7f03626f7ace93b6aa6c76bda90c7

222 Risk Score

Malware Insights

MITRE ATT&CK

T1204 Malicious Link T1566.001 Spearphishing Attachment T1204.002 Malicious File

The RTF document contains an OLE object with decoded Equation Editor payload, strongly indicating exploitation of CVE-2017-11882. The presence of a large, high-entropy embedded artifact within the OLE object suggests it is a packed or obfuscated executable payload. The ".objupdate" directive further confirms the intent to activate the embedded OLE object, likely leading to the execution of the secondary 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 ~1119KB 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_off0000006b.bin` `8c71c9599c16d342bdba89798281d60816881c6d6ad6aa1fa76f13b27c9c87f0`	rtf-objdata-decoded	RTF \objdata at offset 0x6B	560140 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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