Backdoor.Win64.TAIDOOR.YXAH-ENC

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.

However, as of this writing, the said sites are inaccessible.

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.

Installation

This Backdoor drops the following files:

• %All Users Profile%\Microsoft\~svc_.TMp -> INI file
• %Temp%\cmd.exe -> copy of legitimate %System%\cmd.exe

(Note: %All Users Profile% is the common user's profile folder, which is usually C:\Documents and Settings\All Users on Windows 2000(32-bit), XP, and Server 2003(32-bit), or C:\ProgramData on Windows Vista, 7, 8, 8.1, 2008(64-bit), 2012(64-bit) and 10(64-bit). . %System% is the Windows system folder, where it usually is C:\Windows\System32 on all Windows operating system versions.)

Propagation

The said .INF file contains the following strings:

[Micros]
source=%Temp%\cmd.exe

(Note: %Temp% is the Windows temporary folder, where it usually is C:\Windows\Temp on all Windows operating system versions.)

Backdoor Routine

This Backdoor connects to the following URL(s) to send and receive commands from a remote malicious user:

• infonew.{BLOCKED}a.net

However, as of this writing, the said sites are inaccessible.

Other Details

This Backdoor requires the following additional components to properly run:

• {Malware Path}\rasautoex.dll -> Detected as Trojan.Win64.TAIDOOR.YXAH-B