UUID Security Risks and Brute Force Vulnerabilities

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UUIDs (Universally Unique Identifiers) are often assumed to be secure, but this is not always the case. Specifically, UUIDv1 can be predictable and vulnerable to brute-force attacks, leading to security risks in applications that rely on them for authentication or sensitive operations.

You Should Know:

1. UUID Versions and Their Weaknesses

  • UUIDv1: Based on timestamp and MAC address, making it predictable.
  • UUIDv4: Randomly generated, much more secure.
  • UUIDv3/v5: Namespace-based hashes (MD5/SHA-1), deterministic but not ideal for security.

2. How to Check UUID Version in Linux

Use the following command to analyze a UUID:

uuid -d <UUID_STRING>

Example output:

version: 1 
time: 2023-10-05 14:30:00.000000 
node: 00:1a:2b:3c:4d:5e

3. Brute-Forcing UUIDv1 with Python

import uuid 
import time

def generate_sequential_uuids(start_time, count): 
for i in range(count): 
fake_mac = [0x00, 0x16, 0x3e, i % 256, (i // 256) % 256, (i // 65536) % 256] 
fake_node = bytes(fake_mac) 
fake_time = start_time + i  10000000  100-ns intervals 
print(uuid.UUID(fields=(fake_time & 0xFFFFFFFF, 
(fake_time >> 32) & 0xFFFF, 
(fake_time >> 48) & 0x0FFF | 0x1000, 
0x80 | (i % 16), 
fake_node[bash], fake_node[bash], fake_node[bash], 
fake_node[bash], fake_node[bash], fake_node[bash]))

generate_sequential_uuids(int(time.time()  1e7), 10)

4. Mitigation Techniques

  • Use UUIDv4 instead of UUIDv1 for security-sensitive operations.
  • Implement rate-limiting to prevent brute-force attacks.
  • Combine UUIDs with cryptographic tokens for added security.

5. Detecting UUIDv1 in Web Apps

Using `curl` to test API endpoints:

curl -s "https://example.com/api/resource?id=123e4567-e89b-12d3-a456-426614174000" | jq '.uuid_version'

If the response indicates version: 1, the system may be vulnerable.

What Undercode Say

UUIDv1 introduces serious security risks due to its predictability. Developers must avoid using it in authentication, session tokens, or sensitive object references. Instead, UUIDv4 or cryptographically secure alternatives (like JWT tokens) should be used.

For penetration testers, checking UUID versions in APIs and web applications should be part of standard security assessments. Tools like Burp Suite and Python scripts can automate UUID brute-forcing.

Expected Output:

version: 4 
random: True

Prediction

As more systems move toward cryptographically secure identifiers, UUIDv1 usage will decline, but legacy systems will remain vulnerable. Expect increased brute-force attacks targeting UUIDv1 in APIs and web applications.

References:

Reported By: 0x Xnum – Hackers Feeds
Extra Hub: Undercode MoN
Basic Verification: Pass ✅

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