Conditional Compilation
For use with DEFINE for more configurable and efficient payloads
As covered in the Constants section,
DEFINE can be used to declare constants used throughout your payloads. Using DEFINE and some additional commands described below we can gain even more control over the source code that get included into your inject.binduring compilation.Imagine you have a payload that you would like to add some optional features to. With the help of a
DEFINE you could provide a set of boolean constants to toggle those features on or off; consider the example below:DEFINE #EnableExtraFeature1 TRUE
DEFINE #EnableExtraFeature2 FALSE
DEFINE #EnableExtraFeature3 FALSE
... payload ...
IF #EnableExtraFeature1 THEN
... code will always run ...
END_IF
IF #EnableExtraFeature2 THEN
... code will always get skipped at runtime ...
END_IF
IF #EnableExtraFeature3 THEN
... code that will always get skipped at runtime ...
END_IF
Here we have
#EnableExtraFeature1 set to TRUE. At the time of compile IF #EnableExtraFeature1 THEN will become IF TRUE THEN which will allow for the code within that IF statement to be executed. While the payload user is deciding to enable that feature before compiling their
inject.bin by setting #EnableExtraFeature1 to TRUE, the USB Rubber Ducky is still evaluating the IF statement during runtime of the payload even though we know IF TRUE will always evaluate to TRUE. In the opposite case, the features that are disabled are still compiled into the
inject.bin . The USB Rubber Ducky still has to evaluate the IF #EnabledExtraFeature3 THEN which we know will become IF FALSE THEN to decide to skip the code within the IF statement. This becomes not only a waste of space but a waste of computation that could be better used. Using
IF_DEFINED_TRUE IF_NOT_DEFINED_TRUE and ELSE_DEFINED,we can conditionally include portions of our payload in the resulting inject.bin.These act similarly to
IF / ELSE except they are evaluated before compile time and control inclusion or exclusion of blocks of code.
With
IF_DEFINED_TRUE, the code within it's body/block will be compiled into the inject.bin ONLY if the given LABEL exists and evaluates to TRUEIF_DEFINED_TRUE #LABEL
... code ...
END_IF_DEFINED
DEFINE #EnableExtraFeature1 TRUE
DEFINE #EnableExtraFeature2 FALSE
... payload ...
IF_DEFINED_TRUE #EnableExtraFeature1
... code that will be included because #EnableExtraFeature1 is TRUE ...
END_IF_DEFINED
IF_DEFINED_TRUE #EnableExtraFeature2
... code that wont be included because #EnableExtraFeature2 is FALSE ...
END_IF_DEFINED
IF_DEFINED_TRUE #EnableExtraFeature3
... code that wont be included because #EnableExtraFeature3 does not exist ...
END_IF_DEFINED
As the opposite of
IF_DEFINED_TRUE, with IF_NOT_DEFINED_TRUE, the code within it's body/block will be compiled into the inject.bin if the given LABEL does not exist or evaluates to FALSEIF_NOT_DEFINED_TRUE #LABEL
... code ...
END_IF_DEFINED
DEFINE #EnableExtraFeature1 TRUE
DEFINE #EnableExtraFeature2 FALSE
... payload ...
IF_NOT_DEFINED_TRUE #EnableExtraFeature1
... code that wont be included because #EnableExtraFeature1 is TRUE ...
END_IF_DEFINED
IF_NOT_DEFINED_TRUE #EnableExtraFeature2
... code that will be included because #EnableExtraFeature2 is FALSE ...
END_IF_DEFINED
IF_NOT_DEFINED_TRUE #EnableExtraFeature3
... code that will be included because #EnableExtraFeature3 does not exist ...
END_IF_DEFINED
Used in combination with
IF_DEFINED_TRUE and IF_NOT_DEFINED_TRUE to provide the alternative to the provided condition; the negated case. Code within the ELSE_DEFINED body/block will only be included if the paired IF_DEFINED_TRUE or IF_NOT_DEFINED_TRUE case is not met.IF_DEFINED_TRUE #LABEL
... code ...
ELSE_DEFINED
... other code ...
END_IF_DEFINED
IF_NOT_DEFINED_TRUE #LABEL
... code ...
ELSE_DEFINED
... other code ...
END_IF_DEFINED
DEFINE #EnableExtraFeature1 TRUE
DEFINE #EnableExtraFeature2 FALSE
... payload ...
IF_NOT_DEFINED_TRUE #EnableExtraFeature1
... code that wont be included because #EnableExtraFeature1 is TRUE ...
ELSE_DEFINED
... alternative to feature 1 that wont be included because #EnableExtraFeature1 is TRUE ...
END_IF_DEFINED
IF_NOT_DEFINED_TRUE #EnableExtraFeature2
... code that will be included because #EnableExtraFeature2 is FALSE ...
END_IF_DEFINED
IF_NOT_DEFINED_TRUE #EnableExtraFeature3
... code that will be included because #EnableExtraFeature3 does not exist ...
END_IF_DEFINED
Last modified 6mo ago