Backdoor.Win64.FREBNIIS.A
Trojan:MSIL/Malgent!MSR (MICROSOFT); UDS:Trojan.Win64.Agent.a (KASPERSKY)
Windows
Threat Type: Backdoor
Destructiveness: No
Encrypted: Yes
In the wild: Yes
OVERVIEW
Downloaded from the Internet, Dropped by other malware
This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
TECHNICAL DETAILS
152,064 bytes
DLL
No
15 Nov 2022
Arrival Details
This Backdoor arrives on a system as a file dropped by other malware or as a file downloaded unknowingly by users when visiting malicious sites.
Other Details
This Backdoor does the following:
- It requires the presence of w3wp.exe and iisfreb.dll loaded in this executable in order to proceed with its malicious routine.
- It parses HTTP POST request for the following in order to proceed with decrypting the payload:
- /logon.aspx
- /default.aspx
- Specific password parameter
- It allows proxying and remote code execution once the payload is decrypted.
It requires being hosted on a web server in order to proceed with its intended routine.
SOLUTION
9.800
18.274.07
23 Feb 2023
18.275.00
24 Feb 2023
Step 1
Before doing any scans, Windows 7, Windows 8, Windows 8.1, and Windows 10 users must disable System Restore to allow full scanning of their computers.
Step 2
Identify and terminate files detected as Backdoor.Win64.FREBNIIS.A
- Windows Task Manager may not display all running processes. In this case, please use a third-party process viewer, preferably Process Explorer, to terminate the malware/grayware/spyware file. You may download the said tool here.
- If the detected file is displayed in either Windows Task Manager or Process Explorer but you cannot delete it, restart your computer in safe mode. To do this, refer to this link for the complete steps.
- If the detected file is not displayed in either Windows Task Manager or Process Explorer, continue doing the next steps.
Step 3
Scan your computer with your Trend Micro product to delete files detected as Backdoor.Win64.FREBNIIS.A. If the detected files have already been cleaned, deleted, or quarantined by your Trend Micro product, no further step is required. You may opt to simply delete the quarantined files. Please check the following Trend Micro Support pages for more information:
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