HyperDbg Documentation
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  • HyperDbg
  • Getting Started
    • Quick Start
    • FAQ
    • Build & Install
    • Attach to HyperDbg
      • Attach to a remote machine
      • Attach to local machine
      • Start a new process
      • Attach to a running process
  • Using HyperDbg
    • Prerequisites
      • Operation Modes
      • How to create a condition?
      • How to create an action?
      • Signatures
    • User-mode Debugging
      • Principles
      • Examples
        • basics
        • events
          • Getting Results of a System-call
    • Kernel-mode Debugging
      • Principles
      • Examples
        • beginning
          • Connecting To HyperDbg
          • Configuring Symbol Server/Path
        • basics
          • Setting Breakpoints & Stepping Instructions
          • Displaying & Editing & Searching Memory
          • Showing & Modifying Registers and Flags
          • Switching to a Specific Process or Thread
          • Mapping Data & Create Structures, and Enums From Symbols
        • events
          • Managing Events
          • Hooking Any Function
          • Intercepting All SYSCALLs
          • Monitoring Accesses To Structures
          • Triggering Special Instructions
          • Identifying System Behavior
        • Scripting Language Examples
    • Software Development Kit (SDK)
      • Events
        • Conditions
        • Actions
      • IOCTL
        • Event Registration
  • Commands
    • Debugging Commands
      • ? (evaluate and execute expressions and scripts in debuggee)
      • ~ (display and change the current operating core)
      • a (assemble virtual address)
      • load (load the kernel modules)
      • unload (unload the kernel modules)
      • status (show the debuggee status)
      • events (show and modify active/disabled events)
      • p (step-over)
      • t (step-in)
      • i (instrumentation step-in)
      • gu (step-out or go up)
      • r (read or modify registers)
      • bp (set breakpoint)
      • bl (list breakpoints)
      • be (enable breakpoints)
      • bd (disable breakpoints)
      • bc (clear and remove breakpoints)
      • g (continue debuggee or processing kernel packets)
      • x (examine symbols and find functions and variables address)
      • db, dc, dd, dq (read virtual memory)
      • eb, ed, eq (edit virtual memory)
      • sb, sd, sq (search virtual memory)
      • u, u64, u2, u32 (disassemble virtual address)
      • k, kd, kq (display stack backtrace)
      • dt (display and map virtual memory to structures)
      • struct (make structures, enums, data types from symbols)
      • sleep (wait for specific time in the .script command)
      • pause (break to the debugger and pause processing kernel packets)
      • print (evaluate and print expression in debuggee)
      • lm (view loaded modules)
      • cpu (check cpu supported technologies)
      • rdmsr (read model-specific register)
      • wrmsr (write model-specific register)
      • flush (remove pending kernel buffers and messages)
      • prealloc (reserve pre-allocated pools)
      • preactivate (pre-activate special functionalities)
      • output (create output source for event forwarding)
      • test (test functionalities)
      • settings (configures different options and preferences)
      • exit (exit from the debugger)
    • Meta Commands
      • .help (show the help of commands)
      • .debug (prepare and connect to debugger)
      • .connect (connect to a session)
      • .disconnect (disconnect from a session)
      • .listen (listen on a port and wait for the debugger to connect)
      • .status (show the debugger status)
      • .start (start a new process)
      • .restart (restart the process)
      • .attach (attach to a process)
      • .detach (detach from the process)
      • .switch (show the list and switch between active debugging processes)
      • .kill (terminate the process)
      • .process, .process2 (show the current process and switch to another process)
      • .thread, .thread2 (show the current thread and switch to another thread)
      • .pagein (bring the page into the RAM)
      • .dump (save the virtual memory into a file)
      • .formats (show number formats)
      • .script (run batch script commands)
      • .sympath (set the symbol server)
      • .sym (load pdb symbols)
      • .pe (parse PE file)
      • .logopen (open log file)
      • .logclose (close log file)
      • .cls (clear the screen)
    • Extension Commands
      • !a (assemble physical address)
      • !pte (display page-level address and entries)
      • !db, !dc, !dd, !dq (read physical memory)
      • !eb, !ed, !eq (edit physical memory)
      • !sb, !sd, !sq (search physical memory)
      • !u, !u64, !u2, !u32 (disassemble physical address)
      • !dt (display and map physical memory to structures)
      • !track (track and map function calls and returns to the symbols)
      • !epthook (hidden hook with EPT - stealth breakpoints)
      • !epthook2 (hidden hook with EPT - detours)
      • !monitor (monitor read/write/execute to a range of memory)
      • !syscall, !syscall2 (hook system-calls)
      • !sysret, !sysret2 (hook SYSRET instruction execution)
      • !mode (detect kernel-to-user and user-to-kernel transitions)
      • !cpuid (hook CPUID instruction execution)
      • !msrread (hook RDMSR instruction execution)
      • !msrwrite (hook WRMSR instruction execution)
      • !tsc (hook RDTSC/RDTSCP instruction execution)
      • !pmc (hook RDPMC instruction execution)
      • !vmcall (hook hypercalls)
      • !exception (hook first 32 entries of IDT)
      • !interrupt (hook external device interrupts)
      • !dr (hook access to debug registers)
      • !ioin (hook IN instruction execution)
      • !ioout (hook OUT instruction execution)
      • !hide (enable transparent-mode)
      • !unhide (disable transparent-mode)
      • !measure (measuring and providing details for transparent-mode)
      • !va2pa (convert a virtual address to physical address)
      • !pa2va (convert physical address to virtual address)
      • !dump (save the physical memory into a file)
      • !pcitree (show PCI/PCIe device tree)
      • !pcicam (dump the PCI/PCIe configuration space)
      • !idt (show Interrupt Descriptor Table entries)
      • !apic (dump local APIC entries in XAPIC and X2APIC modes)
      • !ioapic (dump I/O APIC)
    • Scripting Language
      • Assumptions & Evaluations
      • Variables & Assignments
      • Casting & Type-awareness
      • Conditionals & Loops
      • Constants & Functions
      • Debugger Script (DS)
      • Examples
        • view system state (registers, memory, variables)
        • change system state (registers, memory, variables)
        • trace function calls
        • pause the debugger conditionally
        • conditional breakpoints and events
        • patch the normal sequence of execution
        • access to a shared variable from different cores
        • count occurrences of events
      • Functions
        • debugger
          • pause
        • events
          • event_enable
          • event_disable
          • event_clear
          • event_sc
          • event_inject
          • event_inject_error_code
          • flush
        • exports
          • print
          • printf
        • interlocked
          • interlocked_compare_exchange
          • interlocked_decrement
          • interlocked_exchange
          • interlocked_exchange_add
          • interlocked_increment
        • memory
          • check_address
          • eb, ed, eq
          • eb_pa, ed_pa, eq_pa
          • memcpy
          • memcpy_pa
          • memcmp
          • virtual_to_physical
          • physical_to_virtual
        • diassembler
          • disassemble_len
          • disassemble_len32
        • spinlocks
          • spinlock_lock
          • spinlock_lock_custom_wait
          • spinlock_unlock
        • strings
          • strlen
          • wcslen
          • strcmp
          • strncmp
          • wcscmp
          • wcsncmp
    • Commands Map
  • Tips & Tricks
    • Considerations
      • Basic concepts in Intel VT-x
      • VMX root-mode vs VMX non-root mode
      • The "unsafe" behavior
      • Script engine in VMX non-root mode
      • Difference between process and thread switching commands
      • Accessing Invalid Address
      • Transparent Mode
    • Nested-Virtualization Environments
      • Supported Virtual Machines
      • Run HyperDbg on VMware
      • Run HyperDbg on Hyper-V
      • Supporting VMware/Hyper-V
      • VMware backdoor I/O ports
    • Misc
      • Event forwarding
      • Event short-circuiting
      • Event calling stage
      • Instant events
      • Message overflow
      • Customize build
        • Increase Communication Buffer Size
        • Number of EPT Hooks in One Page
        • Change Script Engine Limitations
      • Enable and disable events in Debugger Mode
      • Switch to New Process Layout
  • Contribution
    • Style Guide
      • Coding style
      • Command style
      • Doxygen style
    • Logo & Artworks
  • Design
    • Features
      • VMM (Module)
        • Control over NMIs
        • VMX root-mode compatible message tracing
        • Design of !epthook
        • Design of !epthook2
        • Design of !monitor
        • Design of !syscall & !sysret
        • Design of !exception & !interrupt
    • Debugger Internals
      • Events
      • Conditions
      • Actions
      • Kernel Debugger
        • Design Perspective
        • Connection
  • Links
    • Twitter
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    • Discord
    • Matrix
    • Mastodon
    • YouTube
    • hwdbg (Chip Debugger)
    • Doxygen
    • Contribution
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On this page
  • Creating a Condition
  • Adding the condition to the event
Edit on GitHub
  1. Using HyperDbg
  2. Software Development Kit (SDK)
  3. Events

Conditions

Creating a Condition

You can create a buffer that holds a few bytes that will be do anything you want. For example, you might want to check if the current thread is a special thread or check the privilege level of the requesting user or whatever you can do anything you want in your assembly code then at the end of the code, you can decide whether the actions of this event should be executed or not.

This is done by using RAXregister. If you zero the RAXregister, then return (ret), it means that you don't want the event actions to be executed (or in other words, you returned FALSE).

For example, you might decide to run XOR RAX, RAX at the end of your assembly code. This way, the event action will never be executed because RAX is zero, which means FALSE.

Or you can use MOV RAX, 1 at the end of the code, the RAX is non-zero, which means that the event's actions should be executed.

By the way, it depends on your code and the condition of your code.

The following code shows how to create a condition buffer at the kernel.

    //
    // Create condition buffer
    //
    char CondtionBuffer[8];
    CondtionBuffer[0] = 0x90; //nop
    CondtionBuffer[1] = 0x48; //xor rax, rax
    CondtionBuffer[2] = 0x31;
    CondtionBuffer[3] = 0xc0;
    CondtionBuffer[4] = 0x48; // inc rax
    CondtionBuffer[5] = 0xff;
    CondtionBuffer[6] = 0xc0;
    CondtionBuffer[7] = 0xc3; // ret

Don't forget to put a 0xc3 or ret instruction at the end of your condition buffer. This way, you give the program's execution back to the debugger, and HyperDbg can continue normally. Otherwise, the HyperDbg won't get a chance to get back the execution and cause a crash.

Adding the condition to the event

Adding condition buffer to the event is done when you are creating the event using DebuggerCreateEvent, you have to specify both a pointer to the buffer and the size of the buffer.

Look at the following example,

    //
    // Create event based on condition buffer
    //
    PDEBUGGER_EVENT Event1 = DebuggerCreateEvent(
        TRUE,
        DEBUGGER_EVENT_APPLY_TO_ALL_CORES,
        DEBUGGER_EVENT_APPLY_TO_ALL_PROCESSES,
        HIDDEN_HOOK_READ,
        0x85858585,
        sizeof(CondtionBuffer),
        CondtionBuffer);

In the above example, CondtionBuffer is the pointer to the buffer that holds the assembly bytes and sizeof(CondtionBuffer) shows the size of the buffer.

Each event can only have one condition.

The condition buffer function is called in the following form:

typedef UINT64
DebuggerCheckForCondition(PGUEST_REGS Regs, PVOID Context);

The above function is called where Regs is in RCX and Context is in RDX.

Regs is the registers of the guest, you can directly modify them, and it will be applied to the guest in the normal execution, and you can also read these registers in this structure and the Context is event-specific, check each event's documentation to see what is in the Context.

The Regs or RCX is a pointer to the following structure.

typedef struct _GUEST_REGS
{
    ULONG64 rax; // 0x00
    ULONG64 rcx; // 0x08
    ULONG64 rdx; // 0x10
    ULONG64 rbx; // 0x18
    ULONG64 rsp; // 0x20 
    ULONG64 rbp; // 0x28
    ULONG64 rsi; // 0x30
    ULONG64 rdi; // 0x38
    ULONG64 r8;  // 0x40
    ULONG64 r9;  // 0x48
    ULONG64 r10; // 0x50
    ULONG64 r11; // 0x58
    ULONG64 r12; // 0x60
    ULONG64 r13; // 0x68
    ULONG64 r14; // 0x70
    ULONG64 r15; // 0x78
} GUEST_REGS, *PGUEST_REGS;

You can read other registers (non-general purpose registers) directly and modify them. We're not changing them or using them in debugger and hypervisor routines, so reading and changing them will directly apply to the guests' registers and apply to normal execution.

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Last updated 2 years ago