mirror of
https://github.com/carlospolop/hacktricks
synced 2024-12-29 22:43:11 +00:00
859 lines
29 KiB
Markdown
859 lines
29 KiB
Markdown
# Angr - Examples
|
|
|
|
<details>
|
|
|
|
<summary><strong>Support HackTricks and get benefits!</strong></summary>
|
|
|
|
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
|
|
* **Share your hacking tricks by submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
|
|
|
|
</details>
|
|
|
|
{% hint style="info" %}
|
|
If the program is using \*\*`scanf` \*\* to get **several values at once from stdin** you need to generate a state that starts after the **`scanf`**.
|
|
{% endhint %}
|
|
|
|
### Input to reach address (indicating the address)
|
|
|
|
```python
|
|
import angr
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1] # :string
|
|
project = angr.Project(path_to_binary)
|
|
|
|
# Start in main()
|
|
initial_state = project.factory.entry_state()
|
|
# Start simulation
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
# Find the way yo reach the good address
|
|
good_address = 0x804867d
|
|
|
|
# Avoiding this address
|
|
avoid_address = 0x080485A8
|
|
simulation.explore(find=good_address , avoid=avoid_address ))
|
|
|
|
# If found a way to reach the address
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
# Print the string that Angr wrote to stdin to follow solution_state
|
|
print(solution_state.posix.dumps(sys.stdin.fileno()))
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### Input to reach address (indicating prints)
|
|
|
|
```python
|
|
# If you don't know the address you want to recah, but you know it's printing something
|
|
# You can also indicate that info
|
|
|
|
import angr
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
initial_state = project.factory.entry_state()
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
#Successful print
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return b'Good Job.' in stdout_output
|
|
|
|
def should_abort(state):
|
|
#Avoid this print
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return b'Try again.' in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
print(solution_state.posix.dumps(sys.stdin.fileno()))
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### Registry values
|
|
|
|
```python
|
|
# Angr doesn't currently support reading multiple things with scanf (Ex:
|
|
# scanf("%u %u).) You will have to tell the simulation engine to begin the
|
|
# program after scanf is called and manually inject the symbols into registers.
|
|
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
# Address were you want to indicate the relation BitVector - registries
|
|
start_address = 0x80488d1
|
|
initial_state = project.factory.blank_state(addr=start_address)
|
|
|
|
|
|
# Create Bit Vectors
|
|
password0_size_in_bits = 32 # :integer
|
|
password0 = claripy.BVS('password0', password0_size_in_bits)
|
|
|
|
password1_size_in_bits = 32 # :integer
|
|
password1 = claripy.BVS('password1', password1_size_in_bits)
|
|
|
|
password2_size_in_bits = 32 # :integer
|
|
password2 = claripy.BVS('password2', password2_size_in_bits)
|
|
|
|
# Relate it Vectors with the registriy values you are interested in to reach an address
|
|
initial_state.regs.eax = password0
|
|
initial_state.regs.ebx = password1
|
|
initial_state.regs.edx = password2
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
solution0 = solution_state.solver.eval(password0)
|
|
solution1 = solution_state.solver.eval(password1)
|
|
solution2 = solution_state.solver.eval(password2)
|
|
|
|
# Aggregate and format the solutions you computed above, and then print
|
|
# the full string. Pay attention to the order of the integers, and the
|
|
# expected base (decimal, octal, hexadecimal, etc).
|
|
solution = ' '.join(map('{:x}'.format, [ solution0, solution1, solution2 ])) # :string
|
|
print(solution)
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### Stack values
|
|
|
|
```python
|
|
# Put bit vectors in th stack to find out the vallue that stack position need to
|
|
# have to reach a rogram flow
|
|
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
# Go to some address after the scanf where values have already being set in the stack
|
|
start_address = 0x8048697
|
|
initial_state = project.factory.blank_state(addr=start_address)
|
|
|
|
# Since we are starting after scanf, we are skipping this stack construction
|
|
# step. To make up for this, we need to construct the stack ourselves. Let us
|
|
# start by initializing ebp in the exact same way the program does.
|
|
initial_state.regs.ebp = initial_state.regs.esp
|
|
|
|
# In this case scanf("%u %u") is used, so 2 BVS are going to be needed
|
|
password0 = claripy.BVS('password0', 32)
|
|
password1 = claripy.BVS('password1', 32)
|
|
|
|
# Now, in the address were you have stopped, check were are the scanf values saved
|
|
# Then, substrack form the esp registry the needing padding to get to the
|
|
# part of the stack were the scanf values are being saved and push the BVS
|
|
# (see the image below to understan this -8)
|
|
padding_length_in_bytes = 8 # :integer
|
|
initial_state.regs.esp -= padding_length_in_bytes
|
|
|
|
initial_state.stack_push(password0)
|
|
initial_state.stack_push(password1)
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
solution0 = solution_state.solver.eval(password0)
|
|
solution1 = solution_state.solver.eval(password1)
|
|
|
|
solution = ' '.join(map(str, [ solution0, solution1 ]))
|
|
print(solution)
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
In this scenario, the input was taken with `scanf("%u %u")` and the value `"1 1"` was given, so the values **`0x00000001`** of the stack come from the **user input**. You can see how this values starts in `$ebp - 8`. Therefore, in the code we have **subtracted 8 bytes to `$esp` (as in that moment `$ebp` and `$esp` had the same value)** and then we have pushed the BVS.
|
|
|
|
.png>)
|
|
|
|
### Static Memory values (Global variables)
|
|
|
|
```python
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
#Get an address after the scanf. Once the input has already being saved in the memory positions
|
|
start_address = 0x8048606
|
|
initial_state = project.factory.blank_state(addr=start_address)
|
|
|
|
# The binary is calling scanf("%8s %8s %8s %8s").
|
|
# So we need 4 BVS of size 8*8
|
|
password0 = claripy.BVS('password0', 8*8)
|
|
password1 = claripy.BVS('password1', 8*8)
|
|
password2 = claripy.BVS('password2', 8*8)
|
|
password3 = claripy.BVS('password3', 8*8)
|
|
|
|
# Write the symbolic BVS in the memory positions
|
|
password0_address = 0xa29faa0
|
|
initial_state.memory.store(password0_address, password0)
|
|
password1_address = 0xa29faa8
|
|
initial_state.memory.store(password1_address, password1)
|
|
password2_address = 0xa29fab0
|
|
initial_state.memory.store(password2_address, password2)
|
|
password3_address = 0xa29fab8
|
|
initial_state.memory.store(password3_address, password3)
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
# Get the values the memory addresses should store
|
|
solution0 = solution_state.solver.eval(password0,cast_to=bytes).decode()
|
|
solution1 = solution_state.solver.eval(password1,cast_to=bytes).decode()
|
|
solution2 = solution_state.solver.eval(password2,cast_to=bytes).decode()
|
|
solution3 = solution_state.solver.eval(password3,cast_to=bytes).decode()
|
|
|
|
solution = ' '.join([ solution0, solution1, solution2, solution3 ])
|
|
|
|
print(solution)
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### Dynamic Memory Values (Malloc)
|
|
|
|
```python
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
# Get address after scanf
|
|
start_address = 0x804869e
|
|
initial_state = project.factory.blank_state(addr=start_address)
|
|
|
|
# The binary is calling scanf("%8s %8s") so 2 BVS are needed.
|
|
password0 = claripy.BVS('password0', 8*8)
|
|
password1 = claripy.BVS('password0', 8*8)
|
|
|
|
# Find a coupble of addresses that aren't used by the binary (like 0x4444444 & 0x4444454)
|
|
# The address generated by mallosc is going to be saved in some address
|
|
# Then, make that address point to the fake heap addresses were the BVS are going to be saved
|
|
fake_heap_address0 = 0x4444444
|
|
pointer_to_malloc_memory_address0 = 0xa79a118
|
|
initial_state.memory.store(pointer_to_malloc_memory_address0, fake_heap_address0, endness=project.arch.memory_endness)
|
|
fake_heap_address1 = 0x4444454
|
|
pointer_to_malloc_memory_address1 = 0xa79a120
|
|
initial_state.memory.store(pointer_to_malloc_memory_address1, fake_heap_address1, endness=project.arch.memory_endness)
|
|
|
|
# Save the VBS in the new fake heap addresses created
|
|
initial_state.memory.store(fake_heap_address0, password0)
|
|
initial_state.memory.store(fake_heap_address1, password1)
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
solution0 = solution_state.solver.eval(password0,cast_to=bytes).decode()
|
|
solution1 = solution_state.solver.eval(password1,cast_to=bytes).decode()
|
|
|
|
solution = ' '.join([ solution0, solution1 ])
|
|
|
|
print(solution)
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### File Simulation
|
|
|
|
```python
|
|
#In this challenge a password is read from a file and we want to simulate its content
|
|
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
# Get an address just before opening the file with th simbolic content
|
|
# Or at least when the file is not going to suffer more changes before being read
|
|
start_address = 0x80488db
|
|
initial_state = project.factory.blank_state(addr=start_address)
|
|
|
|
# Specify the filena that is going to open
|
|
# Note that in theory, the filename could be symbolic.
|
|
filename = 'WCEXPXBW.txt'
|
|
symbolic_file_size_bytes = 64
|
|
|
|
# Create a BV which is going to be the content of the simbolic file
|
|
password = claripy.BVS('password', symbolic_file_size_bytes * 8)
|
|
|
|
# Create the file simulation with the simbolic content
|
|
password_file = angr.storage.SimFile(filename, content=password)
|
|
|
|
# Add the symbolic file we created to the symbolic filesystem.
|
|
initial_state.fs.insert(filename, password_file)
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
solution = solution_state.solver.eval(password,cast_to=bytes).decode()
|
|
|
|
print(solution)
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
{% hint style="info" %}
|
|
Note that the symbolic file could also contain constant data merged with symbolic data:
|
|
|
|
```python
|
|
# Hello world, my name is John.
|
|
# ^ ^
|
|
# ^ address 0 ^ address 24 (count the number of characters)
|
|
# In order to represent this in memory, we would want to write the string to
|
|
# the beginning of the file:
|
|
#
|
|
# hello_txt_contents = claripy.BVV('Hello world, my name is John.', 30*8)
|
|
#
|
|
# Perhaps, then, we would want to replace John with a
|
|
# symbolic variable. We would call:
|
|
#
|
|
# name_bitvector = claripy.BVS('symbolic_name', 4*8)
|
|
#
|
|
# Then, after the program calls fopen('hello.txt', 'r') and then
|
|
# fread(buffer, sizeof(char), 30, hello_txt_file), the buffer would contain
|
|
# the string from the file, except four symbolic bytes where the name would be
|
|
# stored.
|
|
# (!)
|
|
```
|
|
{% endhint %}
|
|
|
|
### Applying Constrains
|
|
|
|
{% hint style="info" %}
|
|
Sometimes simple human operations like compare 2 words of length 16 **char by char** (loop), **cost** a lot to a **angr** because it needs to generate branches **exponentially** because it generates 1 branch per if: `2^16`\
|
|
Therefore, it's easier to **ask angr get to a previous point** (where the real difficult part was already done) and **set those constrains manually**.
|
|
{% endhint %}
|
|
|
|
```python
|
|
# After perform some complex poperations to the input the program checks
|
|
# char by char the password against another password saved, like in the snippet:
|
|
#
|
|
# #define REFERENCE_PASSWORD = "AABBCCDDEEFFGGHH";
|
|
# int check_equals_AABBCCDDEEFFGGHH(char* to_check, size_t length) {
|
|
# uint32_t num_correct = 0;
|
|
# for (int i=0; i<length; ++i) {
|
|
# if (to_check[i] == REFERENCE_PASSWORD[i]) {
|
|
# num_correct += 1;
|
|
# }
|
|
# }
|
|
# return num_correct == length;
|
|
# }
|
|
#
|
|
# ...
|
|
#
|
|
# char* input = user_input();
|
|
# char* encrypted_input = complex_function(input);
|
|
# if (check_equals_AABBCCDDEEFFGGHH(encrypted_input, 16)) {
|
|
# puts("Good Job.");
|
|
# } else {
|
|
# puts("Try again.");
|
|
# }
|
|
#
|
|
# The function checks if *to_check == "AABBCCDDEEFFGGHH". This is very RAM consumming
|
|
# as the computer needs to branch every time the if statement in the loop was called (16
|
|
# times), resulting in 2^16 = 65,536 branches, which will take too long of a
|
|
# time to evaluate for our needs.
|
|
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
initial_state = project.factory.entry_state()
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
# Get an address to check after the complex function and before the "easy compare" operation
|
|
address_to_check_constraint = 0x8048671
|
|
simulation.explore(find=address_to_check_constraint)
|
|
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
# Find were the input that is going to be compared is saved in memory
|
|
constrained_parameter_address = 0x804a050
|
|
constrained_parameter_size_bytes = 16
|
|
# Set the bitvector
|
|
constrained_parameter_bitvector = solution_state.memory.load(
|
|
constrained_parameter_address,
|
|
constrained_parameter_size_bytes
|
|
)
|
|
|
|
# Indicate angr that this BV at this point needs to be equal to the password
|
|
constrained_parameter_desired_value = 'BWYRUBQCMVSBRGFU'.encode()
|
|
solution_state.add_constraints(constrained_parameter_bitvector == constrained_parameter_desired_value)
|
|
|
|
print(solution_state.posix.dumps(sys.stdin.fileno()))
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
{% hint style="danger" %}
|
|
In some scenarios you can activate **veritesting**, which will merge similar status, in order to save useless branches and find the solution: `simulation = project.factory.simgr(initial_state, veritesting=True)`
|
|
{% endhint %}
|
|
|
|
{% hint style="info" %}
|
|
Another thing you can do in these scenarios is to **hook the function giving angr something it can understand** more easily.
|
|
{% endhint %}
|
|
|
|
### Simulation Managers
|
|
|
|
Some simulation managers can be more useful than others. In the previous example there was a problem as a lot of useful branches were created. Here, the **veritesting** technique will merge those and will find a solution.\
|
|
This simulation manager can also be activated with: `simulation = project.factory.simgr(initial_state, veritesting=True)`
|
|
|
|
```python
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
initial_state = project.factory.entry_state()
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
# Set simulation technique
|
|
simulation.use_technique(angr.exploration_techniques.Veritesting())
|
|
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
|
|
return 'Good Job.'.encode() in stdout_output # :boolean
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output # :boolean
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
print(solution_state.posix.dumps(sys.stdin.fileno()))
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### Hooking/Bypassing one call to a function
|
|
|
|
```python
|
|
# This level performs the following computations:
|
|
#
|
|
# 1. Get 16 bytes of user input and encrypt it.
|
|
# 2. Save the result of check_equals_AABBCCDDEEFFGGHH (or similar)
|
|
# 3. Get another 16 bytes from the user and encrypt it.
|
|
# 4. Check that it's equal to a predefined password.
|
|
#
|
|
# The ONLY part of this program that we have to worry about is #2. We will be
|
|
# replacing the call to check_equals_ with our own version, using a hook, since
|
|
# check_equals_ will run too slowly otherwise.
|
|
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
initial_state = project.factory.entry_state()
|
|
|
|
# Hook the address of the call to hook indicating th length of the instruction (of the call)
|
|
check_equals_called_address = 0x80486b8
|
|
instruction_to_skip_length = 5
|
|
@project.hook(check_equals_called_address, length=instruction_to_skip_length)
|
|
def skip_check_equals_(state):
|
|
#Load the input of the function reading direcly the memory
|
|
user_input_buffer_address = 0x804a054
|
|
user_input_buffer_length = 16
|
|
user_input_string = state.memory.load(
|
|
user_input_buffer_address,
|
|
user_input_buffer_length
|
|
)
|
|
|
|
# Create a simbolic IF that if the loaded string frommemory is the expected
|
|
# return True (1) if not returns False (0) in eax
|
|
check_against_string = 'XKSPZSJKJYQCQXZV'.encode() # :string
|
|
|
|
state.regs.eax = claripy.If(
|
|
user_input_string == check_against_string,
|
|
claripy.BVV(1, 32),
|
|
claripy.BVV(0, 32)
|
|
)
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
solution = solution_state.posix.dumps(sys.stdin.fileno()).decode()
|
|
print(solution)
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### Hooking a function / Simprocedure
|
|
|
|
```python
|
|
# Hook to the function called check_equals_WQNDNKKWAWOLXBAC
|
|
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
initial_state = project.factory.entry_state()
|
|
|
|
# Define a class and a tun method to hook completelly a function
|
|
class ReplacementCheckEquals(angr.SimProcedure):
|
|
# This C code:
|
|
#
|
|
# int add_if_positive(int a, int b) {
|
|
# if (a >= 0 && b >= 0) return a + b;
|
|
# else return 0;
|
|
# }
|
|
#
|
|
# could be simulated with python:
|
|
#
|
|
# class ReplacementAddIfPositive(angr.SimProcedure):
|
|
# def run(self, a, b):
|
|
# if a >= 0 and b >=0:
|
|
# return a + b
|
|
# else:
|
|
# return 0
|
|
#
|
|
# run(...) receives the params of the hooked function
|
|
def run(self, to_check, length):
|
|
user_input_buffer_address = to_check
|
|
user_input_buffer_length = length
|
|
|
|
# Read the data from the memory address given to the function
|
|
user_input_string = self.state.memory.load(
|
|
user_input_buffer_address,
|
|
user_input_buffer_length
|
|
)
|
|
|
|
check_against_string = 'WQNDNKKWAWOLXBAC'.encode()
|
|
|
|
# Return 1 if equals to the string, 0 otherways
|
|
return claripy.If(
|
|
user_input_string == check_against_string,
|
|
claripy.BVV(1, 32),
|
|
claripy.BVV(0, 32)
|
|
)
|
|
|
|
|
|
# Hook the check_equals symbol. Angr automatically looks up the address
|
|
# associated with the symbol. Alternatively, you can use 'hook' instead
|
|
# of 'hook_symbol' and specify the address of the function. To find the
|
|
# correct symbol, disassemble the binary.
|
|
# (!)
|
|
check_equals_symbol = 'check_equals_WQNDNKKWAWOLXBAC' # :string
|
|
project.hook_symbol(check_equals_symbol, ReplacementCheckEquals())
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
solution = solution_state.posix.dumps(sys.stdin.fileno()).decode()
|
|
print(solution)
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### Simulate scanf with several params
|
|
|
|
```python
|
|
# This time, the solution involves simply replacing scanf with our own version,
|
|
# since Angr does not support requesting multiple parameters with scanf.
|
|
|
|
import angr
|
|
import claripy
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
initial_state = project.factory.entry_state()
|
|
|
|
class ReplacementScanf(angr.SimProcedure):
|
|
# The code uses: 'scanf("%u %u", ...)'
|
|
def run(self, format_string, param0, param1):
|
|
scanf0 = claripy.BVS('scanf0', 32)
|
|
scanf1 = claripy.BVS('scanf1', 32)
|
|
|
|
# Get the addresses from the params and store the BVS in memory
|
|
scanf0_address = param0
|
|
self.state.memory.store(scanf0_address, scanf0, endness=project.arch.memory_endness)
|
|
scanf1_address = param1
|
|
self.state.memory.store(scanf1_address, scanf1, endness=project.arch.memory_endness)
|
|
|
|
# Now, we want to 'set aside' references to our symbolic values in the
|
|
# globals plugin included by default with a state. You will need to
|
|
# store multiple bitvectors. You can either use a list, tuple, or multiple
|
|
# keys to reference the different bitvectors.
|
|
self.state.globals['solutions'] = (scanf0, scanf1)
|
|
|
|
scanf_symbol = '__isoc99_scanf'
|
|
project.hook_symbol(scanf_symbol, ReplacementScanf())
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
|
|
# Grab whatever you set aside in the globals dict.
|
|
stored_solutions = solution_state.globals['solutions']
|
|
solution = ' '.join(map(str, map(solution_state.solver.eval, stored_solutions)))
|
|
|
|
print(solution)
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
### Static Binaries
|
|
|
|
```python
|
|
# This challenge is the exact same as the first challenge, except that it was
|
|
# compiled as a static binary. Normally, Angr automatically replaces standard
|
|
# library functions with SimProcedures that work much more quickly.
|
|
#
|
|
# To solve the challenge, manually hook any standard library c functions that
|
|
# are used. Then, ensure that you begin the execution at the beginning of the
|
|
# main function. Do not use entry_state.
|
|
#
|
|
# Here are a few SimProcedures Angr has already written for you. They implement
|
|
# standard library functions. You will not need all of them:
|
|
# angr.SIM_PROCEDURES['libc']['malloc']
|
|
# angr.SIM_PROCEDURES['libc']['fopen']
|
|
# angr.SIM_PROCEDURES['libc']['fclose']
|
|
# angr.SIM_PROCEDURES['libc']['fwrite']
|
|
# angr.SIM_PROCEDURES['libc']['getchar']
|
|
# angr.SIM_PROCEDURES['libc']['strncmp']
|
|
# angr.SIM_PROCEDURES['libc']['strcmp']
|
|
# angr.SIM_PROCEDURES['libc']['scanf']
|
|
# angr.SIM_PROCEDURES['libc']['printf']
|
|
# angr.SIM_PROCEDURES['libc']['puts']
|
|
# angr.SIM_PROCEDURES['libc']['exit']
|
|
#
|
|
# As a reminder, you can hook functions with something similar to:
|
|
# project.hook(malloc_address, angr.SIM_PROCEDURES['libc']['malloc']())
|
|
#
|
|
# There are many more, see:
|
|
# https://github.com/angr/angr/tree/master/angr/procedures/libc
|
|
|
|
import angr
|
|
import sys
|
|
|
|
def main(argv):
|
|
path_to_binary = argv[1]
|
|
project = angr.Project(path_to_binary)
|
|
|
|
initial_state = project.factory.entry_state()
|
|
|
|
#Find the addresses were the lib functions are loaded in the binary
|
|
#For example you could find: call 0x804ed80 <__isoc99_scanf>
|
|
project.hook(0x804ed40, angr.SIM_PROCEDURES['libc']['printf']())
|
|
project.hook(0x804ed80, angr.SIM_PROCEDURES['libc']['scanf']())
|
|
project.hook(0x804f350, angr.SIM_PROCEDURES['libc']['puts']())
|
|
project.hook(0x8048d10, angr.SIM_PROCEDURES['glibc']['__libc_start_main']())
|
|
|
|
simulation = project.factory.simgr(initial_state)
|
|
|
|
def is_successful(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Good Job.'.encode() in stdout_output # :boolean
|
|
|
|
def should_abort(state):
|
|
stdout_output = state.posix.dumps(sys.stdout.fileno())
|
|
return 'Try again.'.encode() in stdout_output # :boolean
|
|
|
|
simulation.explore(find=is_successful, avoid=should_abort)
|
|
|
|
if simulation.found:
|
|
solution_state = simulation.found[0]
|
|
print(solution_state.posix.dumps(sys.stdin.fileno()).decode())
|
|
else:
|
|
raise Exception('Could not find the solution')
|
|
|
|
if __name__ == '__main__':
|
|
main(sys.argv)
|
|
```
|
|
|
|
<details>
|
|
|
|
<summary><strong>Support HackTricks and get benefits!</strong></summary>
|
|
|
|
* Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
|
* Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
* Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
* **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
|
|
* **Share your hacking tricks by submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
|
|
|
|
</details>
|