RTF malware analysis — malicious · 33950724fc49a5f2

MALICIOUS

RTF

1.02 MB First seen: 2020-07-24

MD5: f49ea69e0d5569c0d9fd11c617765f88 SHA-1: c477b2aa7e00c7f57140240f7c51914768e564fd SHA-256: 33950724fc49a5f2217a58b1e7e730cc927ae9443d6f2a88bd3ece122e345872

220 Risk Score

Malware Insights

MITRE ATT&CK

T1203 Exploitation for Client Execution T1566.001 Spearphishing Attachment

The file is an RTF document containing embedded OLE objects, specifically triggering heuristics related to CVE-2017-11882 and Equation Editor. This indicates an attempt to exploit a known vulnerability for code execution. The embedded artifacts, including a large binary file, suggest the potential for a secondary payload download and execution, though the exact nature of the payload is not discernible from the provided evidence.

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 activation — CVE-2017-11882 related high CVE related CVE_2017_11882_ACTIVATION_RELATED

RTF decodes to an Equation.3 ProgID and requests OLE activation with \objemb plus \objupdate. This reaches the legacy Equation Editor attack surface used by CVE-2017-11882/CVE-2018-0802 documents, but the malformed MTEF/native payload needed for stronger 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.
Suspicious extracted artifact high 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.
OLE object data medium RTF_OBJDATA

RTF contains 3 \objdata section(s) — embedded OLE objects
Embedded OLE object medium RTF_OBJEMB

RTF contains \objemb — embedded OLE object

Extracted artifacts 3

Files carved from inside the sample during analysis.

Filename	Kind	Source	Size
`objdata_00_off00000fd7.bin`	rtf-objdata-decoded	RTF \objdata at offset 0xFD7	14085 bytes
SHA-256: `91002c4571abeaa266ed85630e60e9e3eab67f89b8f1d5dab4cd3065d1fc12a1`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): WScript.Arguments.Count - 1, WScript.Arguments(I), WScript.CreateObject("WScript.Shell")
`objdata_01_off00008a20.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x8A20	261 bytes
SHA-256: `b079c7b13ff12bc523d6a8a98d8b8aa05d58f43b48699f25df81bb0c54c5c839`
Detection ClamAV: No threats found Obfuscation or payload: likely Static shellcode analysis recovered command string(s): CmD.exe /C cscript %tmp%\egbo.vbs
`objdata_02_off00009c1a.bin`	rtf-objdata-decoded	RTF \objdata at offset 0x9C1A	256571 bytes
SHA-256: `84b145c2497944bf37350c9b01a95cc1c4896a80c11eabcf0d3922fbf3c41f40`

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