What is Use of Path Manipulation Function (CWE-785)?

TL;DR: Use of Path Manipulation Function without Maximum-sized Buffer (CWE-785) is a security vulnerability where undersized output buffers are used with path manipulation functions, leading to potential buffer overflows and unauthorized code execution. Ensure that all such functions use appropriately sized buffers.

What is Use of Path Manipulation Function without Maximum-sized Buffer?

Use of Path Manipulation Function without Maximum-sized Buffer (CWE-785) is a type of buffer overflow vulnerability that occurs when path manipulation functions are invoked with undersized output buffers. As defined by the MITRE Corporation under CWE-785, and classified by the OWASP Foundation under no direct mapping…

Quick Summary

Use of Path Manipulation Function without Maximum-sized Buffer (CWE-785) is a critical vulnerability that can lead to buffer overflows when path manipulation functions are called with undersized output buffers. This can result in unauthorized code execution, data integrity breaches, and system crashes.

Jump to: Quick Summary · Use of Path Manipulation Function without Maximum-sized Buffer Overview · How Use of Path Manipulation Function without Maximum-sized Buffer Works · Business Impact of Use of Path Manipulation Function without Maximum-sized Buffer · Use of Path Manipulation Function without Maximum-sized Buffer Attack Scenario · How to Detect Use of Path Manipulation Function without Maximum-sized Buffer · How to Fix Use of Path Manipulation Function without Maximum-sized Buffer · Framework-Specific Fixes for Use of Path Manipulation Function without Maximum-sized Buffer · How to Ask AI to Check Your Code for Use of Path Manipulation Function without Maximum-sized Buffer · Use of Path Manipulation Function without Maximum-sized Buffer Best Practices Checklist · Use of Path Manipulation Function without Maximum-sized Buffer FAQ · Vulnerabilities Related to Use of Path Manipulation Function without Maximum-sized Buffer · References · Scan Your Own Site

Use of Path Manipulation Function without Maximum-sized Buffer Overview

What

Use of Path Manipulation Function without Maximum-sized Buffer is a vulnerability where path manipulation functions are invoked with undersized output buffers, leading to potential buffer overflows.

Why it matters

This can result in unauthorized code execution and denial-of-service conditions, compromising system integrity and availability.

Where it occurs

It commonly affects applications that use C/C++, Python, Java, or Node.js for file path manipulation operations without proper buffer size validation.

Who is affected

Developers using languages with built-in path manipulation functions (e.g., realpath() in C/C++ or os.path.normpath() in Python) are at risk if they do not ensure appropriate buffer sizes.

Who is NOT affected

Applications that use robust and secure path normalization mechanisms, such as those provided by modern frameworks like Spring Boot or Django, which handle buffer sizing internally.

How Use of Path Manipulation Function without Maximum-sized Buffer Works

Root Cause

The root cause lies in invoking path manipulation functions with undersized output buffers, leading to potential buffer overflows when the maximum possible result size is exceeded.

Attack Flow

1. Attacker constructs a malicious input that exceeds the allocated buffer size.
2. Path manipulation function processes this oversized input.
3. Buffer overflow occurs due to insufficient buffer allocation.
4. Unauthorized code execution or system crash results from the overflow condition.

Prerequisites to Exploit

• Presence of path manipulation functions with undersized output buffers.
• Input control over the manipulated paths.

Vulnerable Code

#include <limits.h>
char buffer[PATH_MAX - 1];
realpath("/very/long/path/to/exceed/buffer", buffer);

This code is vulnerable because it does not allocate a sufficiently large buffer to handle potential oversized path inputs, leading to potential overflow conditions.

Secure Code

#include <limits.h>
char secure_buffer[PATH_MAX + 1];
realpath("/very/long/path/to/exceed/buffer", secure_buffer);

This code uses an appropriately sized buffer to prevent overflow conditions when handling potentially oversized input paths.

Business Impact of Use of Path Manipulation Function without Maximum-sized Buffer

Confidentiality

• Unauthorized access to sensitive data through buffer overflows.

Integrity

• Data corruption due to unauthorized command execution and memory modifications.

Availability

• System crashes or restarts caused by denial-of-service conditions.

Business Consequences:

1. Financial losses from system downtime and remediation efforts.
2. Compliance violations leading to regulatory fines and penalties.
3. Reputational damage from publicized security breaches.

Use of Path Manipulation Function without Maximum-sized Buffer Attack Scenario

1. Attacker constructs a path with an intentionally long name exceeding the buffer size.
2. The application invokes realpath() or similar function on this oversized input.
3. Buffer overflow occurs, leading to unauthorized code execution.
4. System crashes or restarts due to memory corruption.

How to Detect Use of Path Manipulation Function without Maximum-sized Buffer

Manual Testing

• Check for path manipulation functions with undersized output buffers.
• Ensure that all buffer allocations are large enough to handle maximum possible input sizes.

Automated Scanners (SAST/DAST)

• Static analysis can identify potential issues by analyzing source code.
• Dynamic testing can detect runtime behavior and overflow conditions.

PenScan Detection

PenScan’s scanner engines, such as ZAP and Nuclei, actively test for this issue during automated scans.

False Positive Guidance

False positives may occur if the pattern looks risky but is actually safe due to context a scanner cannot determine. Ensure that buffer sizes are appropriately sized in all cases where path manipulation functions are used.

How to Fix Use of Path Manipulation Function without Maximum-sized Buffer

• Always specify output buffers large enough to handle maximum-size possible results from path manipulation functions.
• Implement robust validation and error handling for path inputs.
• Use secure coding practices to prevent buffer overflows and memory corruption.

Framework-Specific Fixes for Use of Path Manipulation Function without Maximum-sized Buffer

C/C++

#include <limits.h>
char secure_buffer[PATH_MAX + 1];
realpath("/very/long/path/to/exceed/buffer", secure_buffer);

This example ensures that the buffer is large enough to handle oversized path inputs, preventing potential overflow conditions.

How to Ask AI to Check Your Code for Use of Path Manipulation Function without Maximum-sized Buffer

Use of Path Manipulation Function without Maximum-sized Buffer Best Practices Checklist

✅ Always specify output buffers large enough to handle the maximum-size possible result from path manipulation functions. ✅ Implement robust validation for input paths before invoking normalization functions. ✅ Use secure coding practices to prevent buffer overflows and memory corruption.

Use of Path Manipulation Function without Maximum-sized Buffer FAQ

How does Use of Path Manipulation Function without Maximum-sized Buffer work?

It occurs when a function for normalizing paths or file names is invoked with an output buffer that is smaller than the maximum possible size, leading to potential overflow issues.

Why is Use of Path Manipulation Function without Maximum-sized Buffer dangerous?

It can lead to buffer overflows, allowing attackers to execute unauthorized code or cause a denial-of-service condition.

How do I detect Use of Path Manipulation Function without Maximum-sized Buffer in my application?

Manual testing involves checking for path manipulation functions with undersized output buffers. Automated scanners can identify potential issues by analyzing source code and runtime behavior.

What are the common consequences of Use of Path Manipulation Function without Maximum-sized Buffer?

It can result in data integrity breaches, unauthorized command execution, and system crashes or restarts.

How can I prevent Use of Path Manipulation Function without Maximum-sized Buffer?

Always specify output buffers large enough to handle the maximum-size possible result from path manipulation functions.

What is a real-world example of Use of Path Manipulation Function without Maximum-sized Buffer?

A vulnerable code snippet might use an undersized buffer when calling a function like realpath() in C/C++ or os.path.normpath() in Python.

How do I fix Use of Path Manipulation Function without Maximum-sized Buffer using PenScan?

Ensure that all path manipulation functions are called with appropriately sized buffers to prevent overflow conditions.

Vulnerabilities Related to Use of Path Manipulation Function without Maximum-sized Buffer

References

• MITRE CWE-785
• NVD NIST

Scan Your Own Site

Manual code review catches what you know to look for. An automated scan catches what you didn’t. Scan your own website using PenScan to find Use of Path Manipulation Function without Maximum-sized Buffer and other risks before an attacker does.