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Attack Tree Analysis for snaipe/libcsptr

Objective: Achieve Arbitrary Code Execution or DoS via libcsptr

Attack Tree Visualization

Attacker's Goal: Achieve Arbitrary Code Execution or DoS via libcsptr

├── 1. Cause Reference Count Corruption [CRITICAL] │ ├── 1.1 Integer Overflow/Underflow in Reference Count [HIGH RISK] │ │ ├── 1.1.1 Exploit cptr_copy() with Malicious Input (if input influences refcount) [HIGH RISK] │ │ ├── 1.1.2 Exploit cptr_release() with Malicious Input (if input influences refcount) [HIGH RISK] │ │ └── 1.1.4 Exploit race condition in multithreaded environment (if application uses threads) [HIGH RISK] │ │ ├── 1.1.4.1 Multiple threads concurrently call cptr_copy() or cptr_release() on the same cptr_t [HIGH RISK] │ │ └── 1.1.4.2 One thread calls cptr_release() while another accesses the underlying pointer. [HIGH RISK] │ ├── 2. Cause Use-After-Free via Reference Count Manipulation [HIGH RISK] │ ├── 2.1 Force Premature Release (refcount underflow) [HIGH RISK] │ │ ├── 2.1.1 (See 1.1 - Integer Overflow/Underflow leading to refcount = 0) [HIGH RISK] │ └── 4. Exploit Weaknesses in Custom Deleter Functions [CRITICAL] ├── 4.1 Double Free within Deleter │ └── 4.1.1 Deleter function itself calls free() multiple times on the same memory. ├── 4.2 Use-After-Free within Deleter │ └── 4.2.1 Deleter function accesses freed memory. ├── 4.3 Buffer Overflow/Underflow within Deleter │ └── 4.3.1 Deleter function performs unsafe memory operations. └── 4.4 Logic Errors in Deleter └── 4.4.1 Deleter function fails to properly clean up resources, leading to leaks or other vulnerabilities.

Attack Tree Path: 1. Cause Reference Count Corruption [CRITICAL]

  • Description: The core of many attacks against libcsptr involves corrupting the reference count (ref field in the cptr_t structure). This can lead to premature freeing of memory (use-after-free) or preventing memory from being freed (memory leak, potentially leading to DoS).

Attack Tree Path: 1.1 Integer Overflow/Underflow in Reference Count [HIGH RISK]

  • Description: The ref field is likely an integer type. If an attacker can cause this value to wrap around, they can manipulate the lifetime of the managed object.

Attack Tree Path: 1.1.1 Exploit cptr_copy() with Malicious Input [HIGH RISK]

  • Attack Vector: If the application uses cptr_copy() in a way that allows user-controlled input to influence the reference count (even indirectly), an attacker could craft input that causes the count to overflow, potentially leading to a very small or zero value. This could trigger a premature free.
  • Example: Imagine a scenario where cptr_copy() is called repeatedly in a loop, and the number of iterations is based on user input. A very large input could cause an integer overflow.

Attack Tree Path: 1.1.2 Exploit cptr_release() with Malicious Input [HIGH RISK]

  • Attack Vector: Similar to cptr_copy(), if user input can influence how cptr_release() is used, an attacker might be able to cause an underflow. This is less direct than with cptr_copy(), but still possible if the application logic is flawed.
  • Example: A flawed application might decrement the reference count based on user input without proper bounds checking.

Attack Tree Path: 1.1.4 Exploit race condition in multithreaded environment [HIGH RISK]

  • Description: In a multithreaded application, if multiple threads access the same cptr_t object without proper synchronization, race conditions can occur, leading to corruption of the reference count.

Attack Tree Path: 1.1.4.1 Multiple threads concurrently call cptr_copy() or cptr_release() [HIGH RISK]

  • Attack Vector: If two threads call cptr_copy() on the same object simultaneously, the reference count might be incremented only once instead of twice. Similarly, concurrent calls to cptr_release() could decrement the count too many times.
  • Example: Thread 1 reads ref (value: 1), Thread 2 reads ref (value: 1), Thread 1 increments to 2 and writes, Thread 2 increments to 2 and writes. The correct value should be 3.

Attack Tree Path: 1.1.4.2 One thread calls cptr_release() while another accesses the underlying pointer. [HIGH RISK]

  • Attack Vector: If one thread releases the object (decrementing the reference count to zero and freeing the memory) while another thread is still using the pointer obtained via cptr_get(), the second thread will be accessing freed memory (use-after-free).
  • Example: Thread 1 calls cptr_release(), freeing the memory. Thread 2, which previously obtained the pointer via cptr_get(), attempts to access the memory, resulting in a use-after-free.

Attack Tree Path: 2. Cause Use-After-Free via Reference Count Manipulation [HIGH RISK]

  • Description: This is a direct consequence of successfully corrupting the reference count (specifically, causing an underflow).

Attack Tree Path: 2.1 Force Premature Release (refcount underflow) [HIGH RISK]

  • 2.1.1 (See 1.1 - Integer Overflow/Underflow leading to refcount = 0) [HIGH RISK]
    • Attack Vector: This is not a separate attack vector, but rather the result of successfully exploiting the integer overflow/underflow vulnerabilities described in 1.1. If the attacker can force the reference count to zero, the memory will be freed, leading to a use-after-free if other cptr_t objects still point to it.

Attack Tree Path: 4. Exploit Weaknesses in Custom Deleter Functions [CRITICAL]

  • Description: libcsptr allows users to provide custom deleter functions that are executed when the reference count of a cptr_t reaches zero. These functions are responsible for cleaning up the resources associated with the managed object. If these functions are not written carefully, they can introduce vulnerabilities.

Attack Tree Path: 4.1 Double Free within Deleter

  • 4.1.1 Deleter function itself calls free() multiple times on the same memory.
    • Attack Vector: The custom deleter function might contain a logic error that causes it to call free() (or a related deallocation function) more than once on the same memory region.
    • Example: A poorly written deleter might have a conditional statement that, under certain circumstances, leads to free() being called twice.

Attack Tree Path: 4.2 Use-After-Free within Deleter

  • 4.2.1 Deleter function accesses freed memory.
    • Attack Vector: The deleter function might free a resource and then subsequently attempt to access that freed resource.
    • Example: The deleter might free a structure and then try to access a field within that structure.

Attack Tree Path: 4.3 Buffer Overflow/Underflow within Deleter

  • 4.3.1 Deleter function performs unsafe memory operations.
    • Attack Vector: The deleter function might contain a buffer overflow or underflow vulnerability, similar to those found in other C code.
    • Example: The deleter might use strcpy() to copy data into a fixed-size buffer without checking the length of the source data.

Attack Tree Path: 4.4 Logic Errors in Deleter

  • 4.4.1 Deleter function fails to properly clean up resources, leading to leaks or other vulnerabilities.
    • Attack Vector: The deleter might fail to release all associated resources, leading to memory leaks, file handle leaks, or other resource exhaustion issues. While not directly exploitable for code execution, these can lead to denial-of-service.
    • Example: The deleter might free a structure but fail to close a file handle that was opened within that structure.