Binary Ninja Debugger is a plugin that can debug executables on Windows, Linux, and macOS, and more!
The debugger plugin is shipped with Binary Ninja. It is open-source under an Apache License 2.0. Bug reports and pull requests are welcome!
The debugger UI mainly consists of six parts:
- debugger sidebar
- debugger menu
- global area panels
- debugger status widget
- debugger context menu
- stack variable annotations
Clicking the debugger sidebar button (along the left edge of the main window, the one that looks like a bug) will activate the debugger sidebar.
The debugger sidebar contains three widgets: the control buttons, the register widget, and the breakpoint widget.
There is a row of buttons at the top of the debugger sidebar. They control the execution of the target. The behavior of each button is hopefully intuitive from its icon. You can also hover over the button to see the name of the icon.
Buttons that do not work for the current target status are disabled. For example: before launching the target, the
Step Into button is disabled.
A common scenario is to click the left-most button to launch the target and then use the buttons on the right to resume the target, step into/over/return. The
Pause button can be used to break into the target while it is running.
Step Into and
Step Over, if the current view is viewing an IL function, then the operation appears to be performed on that IL, offering a source-code debugging-like experience. However, the underlying operation is still performed at the disassembly level because that is the only thing the backend understands. The high-level operations are simulated, i.e., the debugger may decide to step the target multiple times before finally yielding the control. These are transparent to the users.
Attach To Process... button is clicked, a dialog pops up and shows all the running processes on the system. Selecting one of them and clicking
Attach will attach to the process.
Register widget lists registers and their values. A hint column presents anything interesting pointed to by the register. Currently, only strings and pointers to strings are considered. In the future, we would also annotate variables.
Double-clicking a value enters editing mode, and the user can type in new values for the register. The new value is parsed as hex.
The register widget tracks the last seen value of registers and provides visual feedback. Unchanged values are colored white, changed values are colored blue. User-edited values are colored orange.
An experimental feature is added to shorten the list: registers with a value of zero are not shown in the list. To disable it temporarily, right-click and unselect "Hide Unused Registers".
The breakpoint widget lists breakpoints in the target. There are two columns in it, the left one shows the address in the format of
module + offset, and the right column shows the absolute address.
The context menu of the widget offers to delete a breakpoint or to jump to the address of a breakpoint.
There is a
Debugger menu in the main window menu bar.
It contains duplicates of the debugger control operations available via icons and also shows the hotkeys bound to those actions.
Debug Adapter Settings... menu item will trigger a
Debug Adapter Settings dialog:
Within this dialog, you can select which DebugAdapter to use, as well as configure debugger settings such as command-line arguments or the working directory.
Executable Path specifies the path of the executable to run, and
Input File specifies the input file used to create the database.
These two should be the same if you wish to debug the code in an executable.
However, if you wish to debug a shared library or DLL, they should be different -- the
Input File will be the library or DLL you opened in Binary Ninja, while
Executable Path will be the executable that loads the library or DLL.
For example, if you wish to debug a
sample.dll on Windows, then you should open the
sample.dll in Binary Ninja, and configure the adapter as follows:
Input File: path of sample.dll Executable Path: C:\Windows\System32\rundll32.exe (or the .exe that loads the DLL)
Run in Seperate Terminal will cause the target to run in its own terminal, and the debugger will not be able to monitor its
stdout/stderr, or send input
This is suitable when the target sends complex output, and the debugger's console emulator (which is quite basic now) cannot handle it.
There are several useful actions in the debugger menu that are worth explaining:
Create Stack Viewsplits the active view and navigates to the stack pointer value in the new pane. Very useful for viewing stack variables.
Jump to IPnavigates to the value of the instruction pointer. This is especially helpful when one explores the binary and wishes to get back to the current instruction.
Override IPallows changing the instruction pointer value. This is useful when we wish to revert a branch -- simply set the new IP at the other target of the branch. The new IP defaults to the currently selected address. A dialog will pop up after clicking this action, which allows confirming and editing the new IP.
Global Area Panels¶
The debugger adds four new global area widgets: Target Console (terminal), Debugger Console, Stack Trace, and the Modules List.
Target Console panel simulates a terminal for the target. If the process writes to stdout, the content will be printed here. There is an input box at the bottom, and anything entered into it will be sent to the target's stdin.
Due to a backend limitation, this feature only works on macOS and Linux. On Windows, the target always runs in its own external terminal and all input/output happens there.
On macOS and Linux, the default setting redirects the stdin/stdout here. However, if the user configures the target to run in its terminal (by calling
dbg.request_terminal_emulator = True), then the stdin/stdout will not be redirected, and need to be accessed in the target's terminal.
The debugger console allows the user to execute backend commands and get the result.
On Linux and macOS, the backend is based on LLDB and the console accepts LLDB commands.
On Windows, the backend is based on Windows Debugger Engine, and it supports WinDbg command syntax. All WinDbg extension command, e.g.,
!peb are also supported.
The console supports resuming the target, e.g., stepping.
Like the Python console, all addresses in the debugger console is clickable -- clicking it navigates to the address.
The stack trace widget lists all the threads along with the stack frames.
When the target stops, the active thread is expanded and its stack frames are displayed. Stack traces for other threads are collapsed by default and can be expanded from the UI.
Double-clicking the addresses in the PC (program counter), SP (stack pointer), and FP (frame pointer) column navigates to the address.
The active thread is marked with
(*). Double-clicking another thread will set that as the active thread. As a result, the register widget will show the registers from the new active thread.
The context menu offers to suspend and resume each thread individually. A convenience method is offered to make a thread "solo", which suspends all other threads and resumes the thread. Note, resuming the thread does NOT cause the thread to start executing immediately. It only makes the thread execute the next time the target is resumed, e.g., by pressing the
Step Over button. There are some known issues when suspending/resuming individual threads with LLDB adapter.
The module widget shows the start/end address, size, name, and path information of the target's modules.
Double-clicking the addresses navigates to the address.
Note: on macOS 13, the size of system dylib are calculated wrong. The bizarrely huge size is caused by dyld_shared_cache on macOS, which will be addressed in the future. The size of the main executable is still calculated correctly.
Debugger Status Widget¶
A debugger status widget is added to the main window's status bar. It indicates the current status of the target.
For example, when the target stops, it will include the reason for the stop. When the target exits, the exit code is reported. When an error occurs during certain operations, an error message will also be displayed here.
The widget shows the status of the debugger for the current binary view if a debugging session is active.
The debugger registers a series of useful actions along with keyboard shortcuts. These shortcuts can be customized using Binary Ninja's keybindings support.
Among these actions, target control actions, e.g.,
Step Into have the same effect as the control buttons in the sidebar.
Toggle Breakpoint adds a breakpoint at the current location if there is no breakpoint; otherwise, the existing breakpoint is removed.
Run To Here lets the target execute until the current line is hit.
Stack Variable Annotation¶
When the target breaks and a stack trace is available, the debugger annotates the stack variables in the linear view as data variables.
The above image shows the annotated stack with three stack frames. The start and end of each stack frame are marked, and stack variables are defined according to the stack variables in the functions.
To view the stack variable annotations, switch to the linear view of the Debugger binary view, and then navigate to the stack pointer address (such as by double-clicking the stack pointer in the Registers view).
A useful setup is a split view that shows the code on the left, and the stack on the right. If the user adopts this layout, remember to put the linear view that shows the stack region on a different sync group, so executing the target would not lead to navigation of the linear view. This way, we can observe how variables on the stack change.
In the future, we will offer a way to set up this side-by-side view in one click.
Only the stack frames and variables of the current (active) thread are annotated to avoid confusion. If you wish to view stack variables from a different thread, first switch to that thread in the
Stack Trace global area panel.
The annotation is done only when there are at least two frames in the stack trace. This is a known limitation, and we will address it later.
If the stack variable annotation does not work in certain cases or even causes extra problems, it can be disabled by setting
debugger.stackVariableAnnotations to false.
Other UI Elements¶
On every line that has a breakpoint, there are two visual indicators:
- the line is highlighted in red
- a red breakpoint tag is added to the left
On the line where the program counter is at, there are two visual indicators:
- the line is highlighted in blue
- a program counter tag (=>) is added to the left
The goal of the Binary Ninja debugger is to provide a unified way of debugging programs on different platforms (e.g., Windows, Linux, macOS, etc). However, this is not an easy task, because each platform has its own way of supporting debugging and it varies considerably.
To deal with this, we abstract the core functionalities of a debugger into a class
DebugAdapter. Each debug adapter is a subclass of the
DebugAdapter with the platform-dependent implementation of each method.
The debugger then drives the various adapters, creating a unified debugging experience, both in GUI and API.
Right now, the debugger comes with two debug adapters. The
LLDBAdapter uses LLDB as its backend and debugs programs on macOS and Linux. The
DbgEngAdapter uses Windows debugger engine, and debugs programs on Windows.
New debug adapters can be created by subclassing
DebugAdapter to support other targets.
Remote debugging is a planned feature. Specifically, the capacity to connect to a target via RSP protocol is already baked into the LLDBAdapter, though not tested.
The Debugger BinaryView¶
To represent the memory space of the target, the debugger creates a specialized
DebugProcessView. Throughout this document, it is also called the
The Debugger BinaryView reads and writes its memory from the connected
DebugAdapter. To save on data transfer, the debugger caches all read operations from the adapter. Whenever the debugger executes instructions or writes data, the cached data is cleared.
When the target is launched, the debugger automatically switches the view to the Debugger BinaryView.
The debugger automatically applies all analysis data to the Debugger BinaryView, including functions and types, etc. This means the user can conveniently use types that are present in the static analysis.
The Debugger BinaryView can be accessed by
dbg.live_view once the target is launched. You can read/write to it in the normal way. Writing to it will also cause the target's memory to change.
Right now, the Debugger BinaryView is discarded once the target exits. It cannot be easily reused due to ASLR, which makes the base of the program different in each run. As a result, any changes the user made to the Debugger BinaryView will be discarded after the target exits.
The API is centered around the
DebuggerController class, which provides all functionalities of the debugger. There is no need to directly access the
When the debugger is used within the UI, the
dbg magic variable is injected into the Python interpreter. It always represents the debugger for the currently active Binary View. You can think of it as being created by
dbg = DebuggerController(bv)
bv is another magic variable that always represents the current BinaryView.
You can simply run
dbg.launch() in the Python console to launch the target.
Here is an incomplete guide on how to get started with the debugger, covering most of the basics on operations in the debugger.
Launch and Control the Target¶
There are several ways to launch the target:
- Use the control buttons at the top of the debugger sidebar
- Use the debugger main window menu
- Use the debugger context menu or its keybindings (
- Run LLDB/WinDbg commands in the debugger console
dbg.step_into(), etc. in the Python console.
Configure Launch Parameters¶
- Click "Debugger" -> "Launch/Connect Settings..." in the main window menu, and edit parameters in the dialog
- Directly set the value of
- Select the line, use the
Toggle Breakpointcontext menu or the debugger main window menu
- Select the line, press
- Right-click a line in the Breakpoint widget in the sidebar, and select
dbg.delete_breakpoint(address)in the Python console.
Modify Register Values¶
- Right-click a value item in the Register widget, type in the new value, and hit enter
dbg.regs[reg_name] = valuein the Python console
dbg.set_reg_value(reg_name, value)in the Python console.
- Switch to Linear or hex view of the Debugger BinaryView, and view/edit in the normal way
- Get the Debugger BinaryView by
dbg.live_view, and read/write it in the normal way
Navigating the binary¶
- Double-clicking a value in the register widget, modules widget, and thread frames widget navigates to the address. Note the 0th (first) frame in the stack frame widget usually contains the program counter and the stack pointer, which is used quite often.
- Clicking an address in the debugger console navigates to the address
- Use the
Jump to IPaction to instantly jump back to the current IP
- Use the
Create Stack Viewaction to split the view and navigate to the stack pointer in the new pane
- Use register values in the expression parser. We can use
$regto refer to the value of a register in the expression parser. For example,
$raxevaluates to the value of the
raxregister. We can use
pcto navigate to the current program counter, or
spto navigate to the current stack pointer. Thanks to the power of the expression parse, these register values can be combined with other arithmetic operations. This is especially helpful to quickly navigate to the stack variables since they typically have an address like
$rbp-0x8, which the expression parser can calculate properly:
Time-travel Debugging (beta)¶
Known Issues and Workarounds¶
There are some known issues and limitations with the current debugger. Here is a list including potential workarounds.
Cannot debug binaries that require Administrator (Windows) or root (Linux/macOS). There are two ways to get around it:
- On Windows, run Binary Ninja with Administrator privilege (not recommended).
- Launch the process with necessary privilege, and connect to it using Binary Ninja debugger. See Remote Debugging Guide for more details.
- Must be an admin or in the _developer group on macOS to debug.
- For fat binaries on macOS, the currently viewed architecture will be debugged. For example, if a fat binary contains both x86 and arm code, and the current binary view is x86, then the debugger will debug x86 code in it.
- Cannot debug certain protected applications due to SIP (System Integrity Protection) on macOS. This includes applications in
/Applications. While this can be circumvented by disabling the SIP, it will pose serious threat to the safety of you device. So we do not recommend it and you will need to proceed with it at your own risk.
According to https://lldb.llvm.org/, ARM and AArch64 support should be considered experimental. While in our experience it has worked fairly well, one particular bug we've observed is that single stepping over a return instruction will fail.
If the target contains self-modifying code (SMC), when the target stops, the code in the linear/graph view may not always be up-to-date. To force a memory cache update and re-analysis of the function, right click and select "Reanalyze Current Function" in the context menu.
To avoid the need to manually force an update frequently, set
debugger.aggressiveAnalysisUpdate to true. Then the debugger will explicitly refresh the memory cache and re-analyze all functions every time the target stops. This is very helpful for obfuscated code with lots of SMC. However, it could cause lag in response if the target is large and has a lot of functions.
Changes made to the debugger binary view are lost after debugging¶
Any changes, e.g., annotations, comments, are lost after the target exits. This is because the debugger binary view is a separate binary view, and edits to it would not carry over to the original binary view. As a temporary workaround, try to apply changes to the original binary view, whose changes will always be carried over to the debugger binary view when the target launches.
We are also working on https://github.com/Vector35/debugger/issues/213 which will resolve the problem by offering a viable way to selectively carry over some changes made to the debugger binary view to the original binary view.
While we have tested the debugger in many scenarios, it may still malfunction in certain cases. Here are some basic steps to troubleshoot the situation. If you encounter a bug, please file an issue with reproduction steps, and if possible, attach the binary involved.
- If it crashes Binary Ninja, then it is always considered a bug.
- If the debugger cannot launch the file properly, first check to make sure the file can be executed directly without a debugger.
- Try to relaunch Binary Ninja and retry. There could be unintended side effects from previous debugging sessions. Whether it fixes the problem or not, please file an issue.
- Try to use the LLDB/WinDbg binding that comes with Binary Ninja to debug the file directly. If LLDB/WinDbg can debug it properly, then it is a Binary Ninja issue. Otherwise, it is a bug in the LLDB/WinDbg itself. In both cases, please file an issue and let us know which case it is.
The LLDB/WinDbg path can be found in the following path:
- Windows, user installation: %APPDATA%\Binary Ninja\dbgeng\Windows Kits\10\Debuggers\x64\windbg.exe
- Windows, system installation: %PROGRAMDATA%\Binary Ninja\dbgeng\Windows Kits\10\Debuggers\x64\windbg.exe
- If the program you are debugging is x86, replace
x86in the above path.
- Linux: [Binary Ninja Installation folder]/plugins/lldb/bin/lldb
- macOS: /Applications/Binary Ninja.app/Contents/MacOS/plugins/lldb/bin/lldb
Vector 35 is grateful for the following open source packages that are used in Binary Ninja debugger: