CVE-2023-26154

pubnub insufficient entropy via the getKey function

• CVSS 5.9
• CWE-331 Insufficient Entropy
• Cryptographic
• Remote

Versions of the package pubnub before 7.4.0; all versions of the package com.pubnub:pubnub; versions of the package pubnub before 6.19.0; all versions of the package github.com/pubnub/go; versions of the package github.com/pubnub/go/v7 before 7.2.0; versions of the package pubnub before 7.3.0; versions of the package pubnub/pubnub before 6.1.0; versions of the package pubnub before 5.3.0; versions of the package pubnub before 0.4.0; versions of the package pubnub/c-core before 4.5.0; versions of the package com.pubnub:pubnub-kotlin before 7.7.0; versions of the package pubnub/swift before 6.2.0; versions of the package pubnub before 5.2.0; versions of the package pubnub before 4.3.0 are vulnerable to Insufficient Entropy via the getKey function, due to inefficient implementation of the AES-256-CBC cryptographic algorithm. The provided encrypt function is less secure when hex encoding and trimming are applied, leaving half of the bits in the key always the same for every encoded message or file. **Note:** In order to exploit this vulnerability, the attacker needs to invest resources in preparing the attack and brute-force the encryption.

CVE

CVE-2023-26154

CWE

CWE-331 Insufficient Entropy

CVSS base score

5.9

Published

2023-12-06

OWASP

A02 Cryptographic Failures

Orthogonal defect classification

Algorithm

Code defect classification

Incorrect Algorithm

Category

Cryptographic

Subcategory

Cryptographic Implementation Error

Accessibility scope

Remote

Impact

Unauthorized Access

Fixed by upgrading

Yes

Solution

Update the affected PubNub packages to versions 7.4.0, 6.19.0, 7.2.0, 7.3.0, 6.1.0, 5.3.0, 0.4.0, 4.5.0, 7.7.0, 6.2.0, 5.2.0, 4.3.0, or later

import hashlib
from Crypto.Cipher import AES
from Crypto.Util.Padding import pad

def get_key(secret: str) -> bytes:
    return hashlib.md5(secret.encode()).digest()

def encrypt(plaintext: str, secret: str) -> bytes:
    key = get_key(secret)
    cipher = AES.new(key, AES.MODE_CBC, iv=b'0' * AES.block_size)
    ciphertext = cipher.encrypt(pad(plaintext.encode(), AES.block_size))
    return ciphertext

secret_key = "my_secret"
message = "This is a secret message."
encrypted_message = encrypt(message, secret_key)
print(encrypted_message.hex())

import os
from Crypto.Cipher import AES
from Crypto.Util.Padding import pad
import hashlib

def get_key(secret: str) -> bytes:
    return hashlib.sha256(secret.encode()).digest()

def encrypt(plaintext: str, secret: str) -> bytes:
    key = get_key(secret)
    iv = os.urandom(AES.block_size)
    cipher = AES.new(key, AES.MODE_CBC, iv)
    ciphertext = cipher.encrypt(pad(plaintext.encode(), AES.block_size))
    return iv + ciphertext

secret_key = "my_secure_secret"
message = "This is a secret message."
encrypted_message = encrypt(message, secret_key)
print(encrypted_message.hex())

@misc{vaitp:cve202326154,
  title        = {{pubnub insufficient entropy via the getKey function}},
  author       = {Bogaerts, Fr\'ed\'eric and Ivaki, Naghmeh and Fonseca, Jos\'e},
  year         = {2023},
  note         = {VAITP Python Vulnerability Dataset, entry CVE-2023-26154},
  howpublished = {\url{https://netpack.pt/vaitp/vulnerability/CVE-2023-26154/}}
}