Assumptions & Evaluations

Description of keywords, operators, pseudo-registers, number prefixes, and pre-defined functions

Description

HyperDbg uses a MASM-like (Windbg) syntax to evaluate script expressions.

HyperDbg script engine is case-sensitive.

Keywords

The following keywords are valid in Script Engine.

Keyword	Description
poi	Pointer-sized data from the specified address (dereference)
ref	Reference address of the specified variable
db	Low 8 bits (dereference)
hi	High 16 bits (dereference)
low	Low 16 bits (dereference)
dw	Low 16 bits (dereference)
dd	Low 32 bits (dereference)
dq	64 bits (dereference)
not	Flip each and every bit
neg	True/False logic flipping

If you want to read strings or Unicode strings, you can use the printf function.

Operators

The following operators are supported on the script engine.

Operators Precedence/Priority (Expressions)

Operator	Description
( )	Parentheses
- + ~ * &	Unary Operators (Unary negative, Unary positive, Bitwise not, Reference, Address of)
/ % *	Arithmetic Operators (Division, Modulo, Multiplication)
+ -	Arithmetic Operators (Addition, Subtration)
<< >>	Shift Operators (Right shift, Left shift)
&	Bitwise AND Operator
^	Bitwise XOR Operator (exclusive OR)
|	Bitwise OR Operator

Operator Precedence/Priority (Boolean Expressions)

Operator	Description
( )	Parentheses
- + ~ * &	Unary Operators (Unary negative, Unary positive, Bitwise not, Reference, Address of)
/ % *	Arithmetic Operators (Division, Modulo, Multiplication)
+ -	Arithmetic Operators (Addition, Subtration)
<< >>	Shift Operators (Right shift, Left shift)
>= < > <= == !=	Comparison operators
&	Bitwise AND Operator
^	Bitwise XOR Operator (exclusive OR)
|	Bitwise OR Operator
&&	Logical AND
||	Logical OR

Registers

The following registers are supported by HyperDbg.

Registers	Description
@rax @eax @ax @ah @al @rcx @ecx @cx @ch @cl @rdx @edx @dx @dh @dl @rbx @ebx @bx @bh @bl @rsi @esi @si @sil @rdi @edi @di @dil	General-purpose registers
@r8 @r8d @r8w @r8h @r8l @r9 @r9d @r9w @r9h @r9l @r10 @r10d @r10w @r10h @r10l @r11 @r11d @r11w @r11h @r11l @r12 @r12d @r12w @r12h @r12l @r13 @r13d @r13w @r13h @r13l @r14 @r14d @r14w @r14h @r14l @r15 @r15d @r15w @r15h @r15l	64-bit mode registers
@rsp @esp @sp @spl @rbp @ebp @bp @bpl	Stack management registers
@rip @eip @ip	Program counter (Instruction pointer)
@rflags @eflags @flags	Flags register
@ds @es @cs @ss	Segment registers
@fs @gs	Segment registers (80386)
@cr0 @cr2 @cr3 @cr4 @cr8	Control registers
@gdtr @ldtr @tr	Memory management registers
@idtr	Interrupt descriptor register
@dr0 @dr1 @dr2 @dr3 @dr6 @dr7	Debug registers
Model-/machine-specific registers (MSRs)	See the 'rdmsr' and 'wrmsr' commands for more information.

Each flag of RFLAGS is also supported in HyperDbg.

Bit #	Mask	Register Abbreviation	Description	Category
FLAGS
0	0x0001	@cf	Carry flag	Status
1	0x0002	_	Reserved, always 1 in EFLAGS	_
2	0x0004	@pf	Parity flag	Status
3	0x0008	_	Reserved	_
4	0x0010	@af	Adjust flag	Status
5	0x0020	_	Reserved	_
6	0x0040	@zf	Zero flag	Status
7	0x0080	@sf	Sign flag	Status
8	0x0100	@tf	Trap flag (single step)	Control
9	0x0200	@if	Interrupt enable flag	Control
10	0x0400	@df	Direction flag	Control
11	0x0800	@of	Overflow flag	Status
12-13	0x3000	@iopl	I/O privilege level (286+ only), always 1 on 8086 and 186	System
14	0x4000	@nt	Nested task flag (286+ only), always 1 on 8086 and 186	System
15	0x8000	_	Reserved, always 1 on 8086 and 186, always 0 on later models	_
EFLAGS
16	0x0001 0000	@rf	Resume flag (386+ only)	System
17	0x0002 0000	@vm	Virtual 8086 mode flag (386+ only)	System
18	0x0004 0000	@ac	Alignment check (486SX+ only)	System
19	0x0008 0000	@vif	Virtual interrupt flag (Pentium+)	System
20	0x0010 0000	@vip	Virtual interrupt pending (Pentium+)	System
21	0x0020 0000	@id	Able to use CPUID instruction (Pentium+)	System
22‑31	0xFFC0 0000	_	Reserved	System
RFLAGS
32‑63	0xFFFF FFFF… 0000 0000	Reserved	_	_

Pseudo-registers

Here are the currently supported pseudo-registers supported by the script engine.

Pseudo-register	Description
$pid	The process ID (PID) of the current process.
$proc	The address of the current process (that is, the address of the nt!_EPROCESS block).
$pname	A pointer to the character array of the process name. (It is a 16-byte long array in kernel-mode).
$tid	The thread ID for the current thread.
$core	The core ID for the current core.
$thread	The address of the current thread. In kernel-mode debugging, this address is the address of the nt!_ETHREAD block.
$peb	The address of the process environment block (PEB) of the current process.
$teb	The address of the thread environment block (TEB) of the current thread.
$ip	The instruction pointer register (rip).
$buffer	The pre-allocated buffer if the user requests a safe buffer.
$context	The context of the triggered event (It has a different meaning in each event).
$event_id	The event ID of the triggered event (Only in the case of events). [Added from v0.3]
$event_tag	The event tag of the triggered event (Only in the case of events). [Added from v0.3]
$event_stage	The calling stage of the triggered event (Only in the case of events). [Added from v0.5]

Some of the above pseudo-registers are not supported either in kernel-mode or user-mode. If you use these registers, then it returns NULL.

Number Prefixes

By default, HyperDbg interprets the numbers as hex (base 16). If you want to specify other forms of a number, you should use MASM prefixes. In all MASM expressions, numeric values are interpreted as numbers in the current radix (16, 10, or 8). You can override the default radix by specifying the 0x prefix (hexadecimal), the 0n prefix (decimal), the 0t prefix (octal), or the 0y prefix (binary).

Comments

HyperDbg's comments are like C comments.

A comment starts with a slash asterisk /* and ends with an asterisk slash */ and can be anywhere in your program. Comments can span several lines within your C program.

/* comment goes here */

OR

/*
 * comment goes here
 */

You can create a comment on a single line.

// comment goes here

Strings

There are C-like functions for performing string and wide-character string comparisons. Regular strings are enclosed in double quotations (e.g., "This is a string"), while wide-character strings begin with an 'L' followed by double quotations (e.g., L"This is a wide-character string").

Escape Characters

Special characters such as \n and \t, are used to represent special characters like newline and tab within strings. Additionally, hexadecimal representations between strings, like "\x41\x42\x43", enable the inclusion of specific byte values in a character sequence.

Functions

HyperDbg supports multiple pre-defined functions.