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https://github.com/doronz88/hilda

LLDB wrapped and empowered by iPython's features
https://github.com/doronz88/hilda

debug debugger ios ipython lldb python

Last synced: 10 days ago
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LLDB wrapped and empowered by iPython's features

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README 

        
# Hilda



- [Hilda](#hilda)

  - [Overview](#overview)

  - [Installation](#installation)

  - [How to use](#how-to-use)

    - [Starting a Hilda interactive shell](#starting-a-hilda-interactive-shell)

    - [Inside a Hilda shell](#inside-a-hilda-shell)

      - [Magic functions](#magic-functions)

      - [Key-bindings](#key-bindings)

      - [Configurables](#configurables)

      - [UI Configuration](#ui-configuration)

    - [Python API](#python-api)

      - [Symbol objects](#symbol-objects)

      - [Globalized symbols](#globalized-symbols)

      - [Searching for the right symbol](#searching-for-the-right-symbol)

      - [Objective-C Classes](#objective-c-classes)

      - [Objective-C Objects](#objective-c-objects)

      - [Using snippets](#using-snippets)

  - [Contributing](#contributing)



## Overview



Hilda is a debugger which combines both the power of LLDB and iPython for easier debugging.



The name originates from the TV show "Hilda", which is the best friend of

[Frida](https://frida.re/). Both Frida and Hilda are meant for pretty much the same purpose, except Hilda takes the

more "

debugger-y" approach (based on LLDB).



Currently, the project is intended for iOS/OSX debugging, but in the future we will possibly add support for the

following platforms as well:



- Linux

- Android



Since LLDB allows abstraction for both platform and architecture, it should be possible to make the necessary changes

without too many modifications.



Pull requests are more than welcome 😊.



If you need help or have an amazing idea you would like to suggest, feel free

to [start a discussion 💬](https://github.com/doronz88/hilda/discussions).



## Installation



Requirements for remote iOS device (not required for debugging a local OSX process):



- Jailbroken iOS device

- `debugserver` in device's PATH

  - [You can use this tool in order to obtain the binary](https://github.com/doronz88/debugserver-deploy)

  - After re-signing with new entitlements, you can put the binary in the following path: `/usr/bin/debugserver`



In order to install please run:



```shell

xcrun python3 -m pip install --user -U hilda

```



*⚠️ Please note that Hilda is installed on top of XCode's python so LLDB will be able to use its features.*



## How to use



### Starting a Hilda interactive shell



You can may start a Hilda interactive shell by invoking any of the subcommand:



- `hilda launch /path/to/executable`

  - Launch given executable on current host

- `hilda attach [-p pid] [-n process-name]`

  - Attach to an already running process on current host (specified by either `pid` or `process-name`)

- `hilda remote HOSTNAME PORT`

  - Attach to an already running process on a target host (sepcified by `HOSTNAME PORT`)

- `hilda bare`

  - Only start an LLDB shell and load Hilda as a plugin.

  - Please refer to the following help page if you require help on the command available to you within the lldb shell:



    [lldb command map](https://lldb.llvm.org/use/map.html).



    As a cheatsheet, connecting to a remote platform like so:



    ```shell

    platform connect connect://ip:port

    ```



    ... and attaching to a local process:



    ```shell

    process attach -n proccess_name

    process attach -p proccess_pid

    ```



    When you are ready, just execute `hilda` to move to Hilda's iPython shell.



### Inside a Hilda shell



Upon starting Hilda shell, you are greeted with:



```

Hilda has been successfully loaded! 😎

Use the p global to access all features.

Have a nice flight ✈️! Starting an IPython shell...

```



Here is a gist of methods you can access from `p`:



- `hd`

  - Print a hexdump of given buffer

- `lsof`

  - Get dictionary of all open FDs

- `bt`

  - Print an improved backtrace.

- `disable_jetsam_memory_checks`

  - Disable jetsam memory checks, prevent raising:

      `error: Execution was interrupted, reason: EXC_RESOURCE RESOURCE_TYPE_MEMORY (limit=15 MB, unused=0x0).`

      when evaluating expression.

- `symbol`

  - Get symbol object for a given address

- `objc_symbol`

  - Get objc symbol wrapper for given address

- `inject`

  - Inject a single library into currently running process

- `rebind_symbols`

  - Reparse all loaded images symbols

- `poke`

  - Write data at given address

- `peek`

  - Read data at given address

- `peek_str`

  - Peek a buffer till null termination

- `peek_std_str`

  - Peek a `std::string`

- `stop`

  - Stop process.

- `cont`

  - Continue process.

- `run_for`

  - Run the process for given interval.

- `detach`

  - Detach from process.

      Useful in order to exit gracefully so process doesn't get killed

      while you exit

- `disass`

  - Print disassembly from a given address

- `file_symbol`

  - Calculate symbol address without ASLR

- `get_register`

  - Get value for register by its name

- `set_register`

  - Set value for register by its name

- `objc_call`

  - Simulate a call to an objc selector

- `call`

  - Call function at given address with given parameters

- `monitor` or `breakpoints.add_monitor`

  - Monitor every time a given address is called



      The following options are available:



      ```

      regs={reg1: format}

          will print register values

  

          Available formats:

              x: hex

              s: string

              cf: use CFCopyDescription() to get more informative description of the object

              po: use LLDB po command

              User defined function, will be called like `format_function(hilda_client, value)`.

  

              For example:

                  regs={'x0': 'x'} -> x0 will be printed in HEX format

      expr={lldb_expression: format}

          lldb_expression can be for example '$x0' or '$arg1'

          format behaves just like 'regs' option

      retval=format

          Print function's return value. The format is the same as regs format.

      stop=True

          force a stop at every hit

      bt=True

          print backtrace

      cmd=[cmd1, cmd2]

          run several LLDB commands, one by another

      force_return=value

          force a return from function with the specified value

      name=some_value

          use `some_name` instead of the symbol name automatically extracted from the calling frame

      override=True

          override previous break point at same location

      ```



- `show_current_source`

  - print current source code if possible

- `finish`

  - Run current frame till its end.

- `step_into`

  - Step into current instruction.

- `step_over`

  - Step over current instruction.

- `breakpoints.clear`

  - Remove all breakpoints

- `breakpoints.remove`

  - Remove a single breakpoint

- `force_return`

  - Prematurely return from a stack frame, short-circuiting exection of newer frames and optionally

      yielding a specified value.

- `proc_info`

  - Print information about currently running mapped process.

- `print_proc_entitlements`

  - Get the plist embedded inside the process' __LINKEDIT section.

- `bp` or `breakpoints.add`

  - Add a breakpoint

- `breakpoints.show`

  - Show existing breakpoints

- `po`

  - Print given object using LLDB's po command

      Can also run big chunks of native code:



      po('NSMutableString *s = [NSMutableString string]; [s appendString:@"abc"]; [s description]')

- `globalize_symbols`

  - Make all symbols in python's global scope

- `jump`

  - jump to given symbol

- `lldb_handle_command`

  - Execute an LLDB command

      For example:

      lldb_handle_command('register read')

- `objc_get_class`

  - Get ObjC class object

- `CFSTR`

  - Create CFStringRef object from given string

- `ns`

  - Create NSObject from given data

- `from_ns`

  - Create python object from NS object.

- `evaluate_expression`

  - Wrapper for LLDB's EvaluateExpression.

      Used for quick code snippets.



      Feel free to use local variables inside the expression using format string.

      For example:

      currentDevice = objc_get_class('UIDevice').currentDevice

      evaluate_expression(f'[[{currentDevice} systemName] hasPrefix:@"2"]')

- `import_module`

  - Import & reload given python module (intended mainly for external snippets)

- `unwind`

  - Unwind the stack (useful when get_evaluation_unwind() == False)

- `set_selected_thread`

  - sets the currently selected thread, which is used in other parts of the program, such as displaying disassembly or

      checking registers.

      This ensures the application focuses on the specified thread for these operations.

- `wait_for_module`

  - Wait for a module to be loaded (`dlopen`) by checking if given expression is contained within its filename



All these methods are available from the global `p` within the newly created IPython shell. In addition, you may invoke any of the exported APIs described in the [Python API](#python-api)



#### Magic functions



Sometimes accessing the [Python API](#python-api) can be tiring, so we added some magic functions to help you out!



- `%objc `

  - Equivalent to: `className = p.objc_get_class(className)`

- `%fbp  `

  - Equivalent to: `p.file_symbol(addressInHex, filename).bp()`



#### Key-bindings



- **F1**: Show banner help message

- **F2**: Show process state UI

- **F3**: Toggle stdout/stderr enablement

- **F7**: Step Into

- **F8**: Step Over

- **F9**: Continue

- **F10**: Stop



#### Configurables



The global `cfg` used to configure various settings for evaluation and monitoring.



These settings include:



- `evaluation_unwind_on_error`: Whether to unwind on error during evaluation. (Default: `False`)

- `evaluation_ignore_breakpoints`: Whether to ignore breakpoints during evaluation. (Default: `False`)

- `nsobject_exclusion`: Whether to exclude `NSObject` during evaluation, reducing IPython autocomplete results. (

  Default: `False`)

- `objc_verbose_monitor`: When set to `True`, using `monitor()` will automatically print Objective-C method arguments. (

  Default: `False`)



#### UI Configuration



Hilda contains a minimal UI for examining the target state.

The UI is divided into views:



- Registers

- Disassembly

- Stack

- Backtrace



![img.png](gifs/ui.png)



This UI can be displayed at any time be executing:



```python

ui.show()

```



By default `step_into` and `step_over` will show this UI automatically.

You may disable this behaviour by executing:



```python

ui.active = False

```



Attentively, if you want to display UI after hitting a breakpoint, you can register `ui.show` as callback:



```python

p.symbol(0x7ff7b97c21b0).bp(ui.show)

```



Try playing with the UI settings by yourself:



```python

# Disable stack view

ui.views.stack.active = False



# View words from the stack

ui.views.stack.depth = 10



# View last 10 frames

ui.views.backtrace.depth = 10



# Disassemble 5 instructions

ui.views.disassembly.instruction_count = 5



# Change disassembly syntax to AT&T

ui.views.disassembly.flavor = 'att'



# View floating point registers

ui.views.registers.rtype = 'float'



# Change addresses print color

ui.colors.address = 'red'



# Change titles color

ui.color.title = 'green'

```



### Python API



Hilda provides a comprehensive API wrappers to access LLDB capabilities.

This API may be used to access process memory, trigger functions, place breakpoints and much more!



Also, in addition to access this API using the [Hilda shell](#inside-a-hilda-shell), you may also use pure-python script using any of the `create_hilda_client_using_*` APIs.



Consider the following snippet as an example of such usage:



```python

from hilda.launch_lldb import create_hilda_client_using_attach_by_name



# attach to `sysmond`

p = create_hilda_client_using_attach_by_name('sysmond')



# allocate 10 bytes and print their address

print(p.symbols.malloc(10))



# detach

p.detach()

```



Please note this script must be executed using `xcrun python3` in order for it to be able to access LLDB API.



#### Symbol objects



In Hilda, almost everything is wrapped using the `Symbol` Object. Symbol is just a nicer way for referring to addresses

encapsulated with an object allowing to deref the memory inside, or use these addresses as functions.



In order to create a symbol from a given address, please use:



```python

s = p.symbol(0x12345678)



# the Symbol object extends `int`

True == isinstance(s, int)



# print the un-shifted file address 

# (calculating the ASLR shift for you, so you can just view it in IDA)

print(s.file_address)



# or.. if you know the file address, but don't wanna mess

# with ASLR calculations

s = p.file_symbol(0x12345678)



# peek(/read) 20 bytes of memory

print(s.peek(20))



# write into this memory

s.poke('abc')



# let LLDB print-object (it should guess the type automatically

# based on its memory layout)

print(s.po())



# or you can help LLDB with telling it its type manually

print(s.po('char *'))



# jump to `s` as a function, passing (1, "string") as its args 

s(1, "string")



# change the size of each item_size inside `s` for derefs

s.item_size = 1



# *(char *)s = 1

s[0] = 1



# *(((char *)s)+1) = 1

s[1] = 1



# symbol inherits from int, so all int operations apply

s += 4



# change s item size back to 8 to store pointers

s.item_size = 8



# *(intptr_t *)s = 1

s[0] = 1



# storing the return value of the function executed at `0x11223344`

# into `*s`

s[0] = p.symbol(0x11223344)()  # calling symbols also returns symbols 



# attempt to resolve symbol's name

print(p.symbol(0x11223344).lldb_symbol)



# monitor each time a symbol is called into console and print its backtrace (`bt` option)

# this will create a scripted breakpoint which prints your desired data and continue

s.monitor(bt=True)



# you can also:

#   bt -> view the backtrace

#   regs -> view registers upon each call in your desired format

#   retval -> view the return value upon each call in your desired format

#   cmd -> execute a list of LLDB commands on each hit

s.monitor(regs={'x0': 'x'},  # print `x0` in HEX form

          retval='po',  # use LLDB's `po` for printing the returned value

          bt=True,  # view backtrace (will also resolve ASLR addresses for you)

          cmd=['thread list'],  # show thread list 

          )



# we can also just `force_return` with a hard-coded value to practically disable 

# a specific functionality

s.monitor(force_return=0)  # cause the function to always return `0`



# as for everything, if you need help understanding each such feature, 

# simply execute the following to view its help (many such features even contain examples) 

s.monitor?



# create a scripted_breakpoint manually

def scripted_breakpoint(hilda, *args):

    # like everything in hilda, registers are also

    # just simple `Symbol` objects, so feel free to 

    # use them to your heart's content :)

    if hilda.registers.x0.peek(4) == b'\x11\x22\x33\x44':

        hilda.registers.x0 = hilda.symbols.malloc(200)

        hilda.registers.x0.poke(b'\x22' * 200)



    # just continue the process

    hilda.cont()



s.bp(scripted_breakpoint)



# Place a breakpoint at a symbol not yet loaded by it's name

p.bp('symbol_name')



# In case you need to specify a specific library it's loaded from

p.bp(('symbol_name', 'ModuleName'))

```



#### Globalized symbols



Usually you would want/need to use the symbols already mapped into the currently running process. To do so, you can

access them using `symbols.`. The `symbols` global object is of type `SymbolsJar`, which is a wrapper

to `dict` for accessing all exported symbols. For example, the following will generate a call to the exported

`malloc` function with `20` as its only argument:



```python

x = p.symbols.malloc(20)

```



You can also just write their name as if they already were in the global scope. Hilda will check if no name collision

exists, and if so, will perform the following lazily for you:



```python

x = malloc(20)



# is equivalent to:

malloc = p.symbols.malloc

x = malloc(20)

```



#### Searching for the right symbol



Sometimes you don't really know where to start your research. All you have is just theories of how your desired exported

symbol should be called (if any).



For that reason alone, we have the `rebind_symbols()`

command - to help you find the symbol you are looking for.



```python

p.rebind_symbols()  # this might take some time



# find all symbols prefixed as `mem*` AND don't have `cpy`

# in their name

jar = p.symbols.startswith('mem') - p.symbols.find('cpy')



# filter only symbols of type "code" (removing data global for example)

jar = jar.code()



# monitor every time each one is called, print its `x0` in HEX

# form and show the backtrace

jar.monitor(regs={'x0': 'x'}, bt=True)

```



#### Objective-C Classes



The same as symbols applies to Objective-C classes name resolution. You can either:



```python

d = NSDictionary.new()  # call its `new` selector



# which is equivalent to:

NSDictionary = p.objc_get_class('NSDictionary')

d = NSDictionary.new()



# Or you can use the IPython magic function

%objc

NSDictionary

```



This is possible only since `NSDictionary` is exported. In case it is not, you must call `objc_get_class()` explicitly.



As you can see, you can directly access all the class' methods.



Please look what more stuff you can do as shown below:



```python

# show the class' ivars

print(NSDictionary.ivars)



# show the class' methods

print(NSDictionary.methods)



# show the class' proprties

print(NSDictionary.properties)



# view class' selectors which are prefixed with 'init'

print(NSDictionary.symbols_jar.startswith('-[NSDictionary init'))



# you can of course use any of `SymbolsJar` over them, for example:

# this will `po` (print object) all those selectors returned value

NSDictionary.symbols_jar.startswith('-[NSDictionary init').monitior(retval='po')



# monitor each time any selector in NSDictionary is called

NSDictionary.monitor()



# `force_return` for some specific selector with a hard-coded value (4)

NSDictionary.get_method('valueForKey:').address.monitor(force_return=4)



# capture the `self` object at the first hit of any selector

# `True` for busy-wait for object to be captured

dictionary = NSDictionary.capture_self(True)



# print a colored and formatted version for class layout

dictionary.show()

```



#### Objective-C Objects



In order to work with ObjC objects, each symbol contains a property called

`objc_symbol`. After calling, you can work better with each object:



```python

dict = NSDictionary.new().objc_symbol

dict.show()  # print object layout



# just like class, you can access its ivars, method, etc...

print(dict.ivars)



# except now they have values you can view

print(dict._ivarName)



# or edit

dict._ivarName = value



# and of course you can call the object's methods

# hilda will checks if the method returned an ObjC object:

#   - if so, call `objc_symbol` upon it for you

#   - otherwise, leave it as a simple `Symbol` object

arr = dict.objectForKey_('keyContainingNSArray')



# you can also call class-methods

# hilda will call it using either the instance object,

# or the class object respectively of the use

newDict = dict.dictionary()



# print the retrieved object

print(arr.po())

```



Also, working with Objective-C objects like this can be somewhat exhausting, so we created the `ns` and `from_ns`

commands so you are able to use complicated types when parsing values and passing as arguments:



```python

import datetime



# using the `ns` command we can just pass a python-native dictionary

function_requiring_a_specfic_dictionary(ns({

    'key1': 'string',  # will convert to NSString

    'key2': True,  # will convert to NSNumber

    'key3': b'1234',  # will convert to NSData

    'key4': datetime.datetime(2021, 1, 1)  # will convert to NSDate

}))



# and also parse one

normal_python_dict = p.cf({

    'key1': 'string',  # will convert to NSString

    'key2': True,  # will convert to NSNumber

    'key3': b'1234',  # will convert to NSData

    'key4': datetime.datetime(2021, 1, 1)  # will convert to NSDate

}).py()

```



On last resort, if the object is not serializable for this to work, you can just run pure Objective-C code:



```python

# let LLDB compile and execute the expression

abc_string = p.evaluate_expression('[NSString stringWithFormat:@"abc"]')



# will print "abc"

print(abc_string.po())

```



#### Using snippets



Snippets are extensions for normal functionality used as quick cookbooks for day-to-day tasks of a debugger.



They all use the following concept to use:



```python

from hilda.snippets import snippet_name



snippet_name.do_domething()  

```



For example, XPC sniffing can be done using:



```python

from hilda.snippets import xpc



xpc.sniff_all()

```



This will monitor all XPC related traffic in the given process.



## Contributing



Please run the tests as follows before submitting a PR:



```shell

xcrun python3 -m pytest

```