? (evaluate and execute expressions and scripts in debuggee)

Description of the '?' command in HyperDbg.

Command

?

Syntax

? [Expression (string)]

Description

Evaluates and executes an expression in the remote debuggee or in the user debugger.

You can write multiline scripts by putting the scripts between two curly brackets.

For example,

? {

printf("first line");

printf("second line");

printf("third line");

}

Parameters

[Expression (string)]

The expression is based on HyperDbg's scripting language.

Examples

The following command shows the @rax register along with the process name and process ID in the debuggee by calling the printf function.

0: kHyperDbg> ? printf("The RAX register is: %llx at Process Name: %s (pid: %x)", @rax, $pname, $pid);

You can use register assignment within scripts (You can change the value of registers).

0: kHyperDbg> ? @rax = 0x55;	        // change the RAX register value

0: kHyperDbg> ? @cr0 = @cr0 | 0x4;        // set the third bit of CR0 register

0: kHyperDbg> ? @zf = 1;   	        // set the Zero Flag

0: kHyperDbg> ? @ebx = @ecx + 10 + @ax;   // set the value of EBX register

HyperDbg supports conditional statements like if, elsif, and else. You can use any expressions, registers, pseudo-registers, variables, or results of functions in the if, elsif statements.

0: kHyperDbg> ? {
    if (@rax == 55) {
    	     printf("rax is equal to 0x55");
    }
}

0: kHyperDbg> ? {
    if (poi(@rcx + 0x10) == ffff7080deadbeef && @rdx != 55 || $pid == 4) {
    	     printf("condition is met\n");
    }
}

0: kHyperDbg> ? {
    if (check_address(@r11) == 1) { 
    	     printf("address is valid.\n");
    }
    else
    {
	     printf("address is invalid.\n");
    }
}

For loops and nested loops are supported.

0: kHyperDbg> ? {
for (i = 0; i < 10 ; i++) {
       for (j = 0; j < 10; j++) {
       	  printf("%d, %d\n", i, j); 
       }
    }
 }

If you want to change memory, you can use eq, ed, eb functions.

0: kHyperDbg> ? {

	if (eq(@r11, 0x12345678deadbeef) == 1) { 
	    printf("changes are applied.\n");
	}
	else {
            printf("changes are NOT applied.\n");
	}
}

There are many functions and examples available for HyperDbg’s script engine.

Arguments

Arguments to the script are passed to the script by using the $arg0, $arg1, $arg2, ..., $arg100, ..., $arg1000 and so on. HyperDbg uses the ‘.ds’ extension for the script files.

The first argument ($arg0) is the script's .ds file path. Arguments can be both an expression, a constant, or a string. Constants are considered in hex format if no prefix is specified.

Example

? { 
      printf("First argument is : %llx\n", $arg1);
      printf("Result of rax + rbx is : %llx\n", $arg2);
}

We run the above script like by using the “.script” command.

0: kHyperDbg> .script "C:\path to script\script.ds" 55 @rax+@rbx

IOCTL

To run a script on the target process (thread) in the user debugger or in the target debuggee in the kernel debugger, you need to use the following function in libhyperdbg:

BOOLEAN
hyperdbg_u_run_script(CHAR * Expr, BOOLEAN ShowErrorMessageIfAny);

Remarks

Other aliases for this command are 'eval' and 'evaluate'.

You can check the definition and examples of script engine functions, as well as examples for using scripts.

To use this command, you must either be in debugger mode, or in VMI mode with the user debugger attached to a thread. Otherwise, the command runs in test mode (register and system state are not valid in the test mode since you are not connected to any debuggee).

This command is guaranteed to keep debuggee in a halt state (in Debugger Mode); thus, nothing will change during its execution.

Requirements

None

Related

None