RTF malware analysis — malicious · 6536f2905a5d4aaf

MALICIOUS

RTF

7.61 MB First seen: 2020-09-15

MD5: f8ce7894232e490a0e1327548948b75f SHA-1: 3feaabadc35976cb42e9ddac4e05a8bb4746090f SHA-256: 6536f2905a5d4aafcd8835b149b417bd78bfb23869490ed5dbf139a0a162114b

222 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The RTF file contains a critical heuristic firing for CVE-2017-11882, indicating the exploitation of a known vulnerability in Microsoft Equation Editor. The presence of a large, high-entropy OLE object within the RTF suggests it is used to hide and deliver a second-stage payload. The file's structure and the specific exploit targeted point towards a malicious document designed for initial execution.

Heuristics 6

Split hex Equation Editor ProgID + OLE object critical CVE likely RTF_EQUATION_EDITOR

RTF embeds the Equation.3 ProgID as hex bytes near OLE object activation and splits the byte stream with whitespace or an ignorable RTF group. This is an Equation Editor OLE activation surface commonly used by CVE-2017-11882 / CVE-2018-0802 exploit documents.
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.
\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 ~7979KB 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_off0000006f.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x6F	3989932 bytes
SHA-256: `8b377e217d1df954fea351169236e3a964d2f6295df76368b39fb8a560298397`
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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