CVE-2008-4126
PyDNS (python-dns) <2.3.1-5 in Debian: DNS spoofing, no random source ports, incomplete fix
- CVSS 6.4
- CWE-16
- Cryptographic
- Remote
PyDNS (aka python-dns) before 2.3.1-5 in Debian GNU/Linux does not use random source ports for DNS requests and does not use random transaction IDs for DNS retries, which makes it easier for remote attackers to spoof DNS responses, a different vulnerability than CVE-2008-1447. NOTE: this vulnerability exists because of an incomplete fix for CVE-2008-4099.
- CWE
- CWE-16
- CVSS base score
- 6.4
- Published
- 2008-09-18
- OWASP
- A06 Vulnerable and Outdated Components
- Orthogonal defect classification
- Function
- Code defect classification
- Incorrect Functionality
- Category
- Cryptographic
- Subcategory
- Inadequate random number generation
- Accessibility scope
- Remote
- Impact
- Denial of Service (DoS)
- Fixed by upgrading
- Yes
Solution
Update PyDNS (python-dns) to version 2.3.1-5 or higher.
Vulnerable code sample
import socket
import struct
class DNS:
def __init__(self, server='8.8.8.8'):
self.server = server
self.port = 53
self.transaction_id = 0
def query(self, domain):
query = struct.pack('>H', self.transaction_id) + b'\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00' + domain.encode() + b'\x00\x00\x01\x00\x01'
with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as sock:
sock.sendto(query, (self.server, self.port))
sock.settimeout(5)
try:
response, _ = sock.recvfrom(512)
return response
except socket.timeout:
return None
dns_client = DNS()
response = dns_client.query('example.com')
print(response)Patched code sample
import random
import socket
import struct
class DNS:
def __init__(self, server='8.8.8.8'):
self.server = server
def random_port(self):
return random.randint(1024, 65535)
def random_transaction_id(self):
return random.randint(0, 65535)
def query(self, domain):
transaction_id = self.random_transaction_id()
port = self.random_port()
query = struct.pack('>H', transaction_id) + b'\x01\x00\x00\x01\x00\x00\x00\x00\x00\x00' + domain.encode() + b'\x00\x00\x01\x00\x01'
with socket.socket(socket.AF_INET, socket.SOCK_DGRAM) as sock:
sock.bind(('', port))
sock.sendto(query, (self.server, 53))
sock.settimeout(5)
try:
response, _ = sock.recvfrom(512)
return response
except socket.timeout:
return None
dns_client = DNS()
response = dns_client.query('example.com')
print(response)Cite this entry
@misc{vaitp:cve20084126,
title = {{PyDNS (python-dns) <2.3.1-5 in Debian: DNS spoofing, no random source ports, incomplete fix}},
author = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
year = {2008},
note = {VAITP Python Vulnerability Dataset, entry CVE-2008-4126},
howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2008-4126/}}
}Introducing the "VAITP dataset": a specialized repository of Python vulnerabilities and patches, meticulously compiled for the use of the security research community. As Python's prominence grows, understanding and addressing potential security vulnerabilities become crucial. Crafted by and for the cybersecurity community, this dataset offers a valuable resource for researchers, analysts, and developers to analyze and mitigate the security risks associated with Python. Through the comprehensive exploration of vulnerabilities and corresponding patches, the VAITP dataset fosters a safer and more resilient Python ecosystem, encouraging collaborative advancements in programming security.
The supreme art of war is to subdue the enemy without fighting.
Sun Tzu – “The Art of War”
:: Shaping the future through research and ingenuity ::