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Attack Tree Analysis for myclabs/deepcopy

Objective: Compromise application using myclabs/deepcopy by exploiting vulnerabilities within the library or its usage.

Attack Tree Visualization

Attack Goal: Compromise Application Using deepcopy [CRITICAL NODE]
├───[OR]─ Exploit Unserialization Vulnerabilities in deepcopy [CRITICAL NODE] [HIGH-RISK PATH]
│   ├───[AND]─ Object Injection via Unserialization [CRITICAL NODE] [HIGH-RISK PATH]
│   │   ├───[AND]─ Application uses deepcopy on untrusted, serialized data [CRITICAL NODE] [HIGH-RISK PATH]
│   │   │   ├───[AND]─ Attacker crafts malicious serialized object [HIGH-RISK PATH]
│   │   │   │   ├───[AND]─ Malicious object exploits PHP's magic methods (__wakeup, __destruct, __toString, etc.) [HIGH-RISK PATH]
│   │   │   │   └───[AND]─ deepcopy triggers unserialization of the malicious object [HIGH-RISK PATH]
├───[OR]─ Cause Denial of Service (DoS) via deepcopy [CRITICAL NODE] [HIGH-RISK PATH]
│   ├───[AND]─ Recursive Deep Copy leading to Stack Overflow/Resource Exhaustion [CRITICAL NODE] [HIGH-RISK PATH]
│   │   ├───[AND]─ Application deep copies objects with circular references [CRITICAL NODE] [HIGH-RISK PATH]
│   │   │   ├───[AND]─ Attacker provides input that creates or exploits circular references in objects to be deep copied [HIGH-RISK PATH]
│   │   └───[AND]─ deepcopy implementation is vulnerable to infinite recursion on circular references [HIGH-RISK PATH]
│   │       ├───[AND]─ deepcopy does not properly detect or handle circular references [HIGH-RISK PATH]

Attack Tree Path: Object Injection via Unserialization [HIGH-RISK PATH, CRITICAL NODE]

1. Object Injection via Unserialization [HIGH-RISK PATH, CRITICAL NODE]:

  • Attack Vector Name: PHP Object Injection via deepcopy
  • Attack Steps:
    • Step 1: Application uses deepcopy on untrusted, serialized data [CRITICAL NODE]: The application must be processing serialized data from an external, untrusted source (e.g., user input, external API response, file upload) and then using deepcopy on this data. This is the crucial enabling condition.
    • Step 2: Attacker crafts malicious serialized object [HIGH-RISK PATH]: The attacker crafts a specially designed serialized PHP object. This object is designed to exploit PHP's magic methods, such as __wakeup(), __destruct(), __toString(), __call(), etc. These magic methods are automatically invoked during certain object lifecycle events, including unserialization.
    • Step 3: Malicious object exploits PHP's magic methods (__wakeup, __destruct, __toString, etc.) [HIGH-RISK PATH]: The crafted malicious object's magic methods contain code that, when executed, performs malicious actions. This could include:
      • Remote Code Execution (RCE): Executing arbitrary system commands.
      • File system manipulation: Reading, writing, or deleting files.
      • Database manipulation: Modifying or exfiltrating database data.
      • Privilege escalation: Gaining higher privileges within the application or system.
    • Step 4: deepcopy triggers unserialization of the malicious object [HIGH-RISK PATH]: When the application passes the untrusted, serialized data to deepcopy, the library, in its process of deep copying, might trigger the PHP unserialization mechanism (even if indirectly). This causes PHP to unserialize the malicious object, automatically invoking the attacker-controlled magic methods and executing the malicious payload.
  • Impact: Remote Code Execution (RCE), full system compromise, data breach, data manipulation, denial of service. This is the highest impact vulnerability.
  • Mitigation:
    • Absolutely avoid using deepcopy directly on untrusted, serialized data. This is the most critical mitigation.
    • If you must process serialized data, deserialize it using safe methods and validate/sanitize the resulting data before using deepcopy.
    • Review the deepcopy library's source code to understand if and how it handles serialization and unserialization internally. If it uses unserialize() or similar functions, be extremely cautious.

Attack Tree Path: Denial of Service (DoS) via Recursive Deep Copy - Attacker Controlled Circular References [HIGH-RISK PATH, CRITICAL NODE]

2. Denial of Service (DoS) via Recursive Deep Copy - Attacker Controlled Circular References [HIGH-RISK PATH, CRITICAL NODE]:

  • Attack Vector Name: Recursive Deep Copy DoS (Attacker Controlled Circular References)
  • Attack Steps:
    • Step 1: Application deep copies objects with circular references [CRITICAL NODE]: The application attempts to deep copy objects that contain circular references. This can happen unintentionally in complex object structures or when processing external data that can be manipulated by an attacker.
    • Step 2: Attacker provides input that creates or exploits circular references in objects to be deep copied [HIGH-RISK PATH]: The attacker crafts input data that, when processed by the application, results in the creation of objects with circular references. This input is then passed to the part of the application that uses deepcopy.
    • Step 3: Recursive Deep Copy leading to Stack Overflow/Resource Exhaustion [CRITICAL NODE]: When deepcopy attempts to copy the object with circular references, a naive or vulnerable implementation will enter an infinite recursion loop. Each recursive call consumes stack space and/or memory. This rapidly leads to:
      • Stack Overflow: Exhausting the call stack, causing the application to crash.
      • Resource Exhaustion: Consuming excessive CPU and memory, leading to application slowdown or complete denial of service.
  • Impact: Denial of Service (DoS), application crash, server resource exhaustion, degraded application performance.
  • Mitigation:
    • Implement circular reference detection before using deepcopy. Use algorithms like graph traversal to detect cycles in the object graph before attempting to deep copy.
    • Limit recursion depth in your application's usage of deepcopy. Set a maximum recursion level to prevent runaway recursion.
    • Consider using iterative deep copy approaches instead of purely recursive ones, as iterative methods can be more resistant to stack overflow issues.
    • Review the deepcopy library's source code to see if it has built-in circular reference detection and handling. If not, consider patching or choosing a library that does.

Attack Tree Path: Denial of Service (DoS) via Recursive Deep Copy - deepcopy Library Vulnerability [HIGH-RISK PATH, CRITICAL NODE]

3. Denial of Service (DoS) via Recursive Deep Copy - deepcopy Library Vulnerability [HIGH-RISK PATH, CRITICAL NODE]:

  • Attack Vector Name: Recursive Deep Copy DoS (deepcopy Library Vulnerability)
  • Attack Steps:
    • Step 1: Application deep copies objects with circular references [CRITICAL NODE]: Similar to the previous DoS vector, the application attempts to deep copy objects that contain circular references.
    • Step 2: deepcopy implementation is vulnerable to infinite recursion on circular references [HIGH-RISK PATH]: The deepcopy library itself has a vulnerability in its circular reference handling. Specifically, it:
      • Does not properly detect circular references [HIGH-RISK PATH]: The library fails to identify and handle circular references in the object graph.
      • Leads to infinite recursion: As a result of not detecting circular references, the deep copy algorithm enters an infinite recursion loop when encountering them.
    • Step 3: Recursive Deep Copy leading to Stack Overflow/Resource Exhaustion [CRITICAL NODE]: The infinite recursion within deepcopy leads to the same consequences as in the previous DoS vector: stack overflow, resource exhaustion, and denial of service.
  • Impact: Denial of Service (DoS), application crash, server resource exhaustion, degraded application performance.
  • Mitigation:
    • Review deepcopy's source code for circular reference handling. Specifically, check if it has mechanisms to detect and prevent infinite recursion when encountering circular references.
    • If the library lacks robust circular reference handling, consider patching it to add detection and prevention mechanisms.
    • Alternatively, choose a different deep copy library that is known to handle circular references safely and efficiently.
    • As a general precaution, even if the library claims to handle circular references, it's still good practice to implement circular reference checks in your application before calling deepcopy, as a defense-in-depth measure.

These detailed breakdowns should provide a clear understanding of the high-risk attack vectors related to using deepcopy and guide the development team in implementing effective mitigations. Remember to prioritize addressing the Object Injection and DoS vulnerabilities due to their high potential impact.