Skip to main content

Insecure generation of random numbers - Static IV

Description​

The application uses static, hardcoded values for initialization vectors. By knowing initialization vectors an attacker could perform a reverse engineering attack to predict the random values that should remain as secrets.

Impact​

Predict random values to craft new attack vectors.

Recommendation​

Generate initialization vectors randomly using mechanisms with secure randomness and high entropy.

Threat​

Authenticated attacker from the Internet with access to the source code.

Expected Remediation Time​

⌚ 30 minutes.

Score​

Default score using CVSS 3.1. It may change depending on the context of the vulnerability.

Base​

  • Attack vector: N
  • Attack complexity: H
  • Privileges required: L
  • User interaction: N
  • Scope: U
  • Confidentiality: L
  • Integrity: N
  • Availability: N

Temporal​

  • Exploit code madurity: P
  • Remediation level: U
  • Report confidence: C

Result​

  • Vector string: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:U/C:L/I:N/A:N/E:P/RL:U/RC:C
  • Score:
    • Base: 3.1
    • Temporal: 3.0
  • Severity:
    • Base: Low
    • Temporal: Low

Code Examples​

Compliant code​

The application includes secure encryption algorithms

from Crypto import Random
from Crypto.Cipher import AES
from Crypto.Util.Padding import paddef encrypt(value, key):
  value = value.encode('ascii')
  iv = Random.new().read(AES.block_size)
  cipher = AES.new(key, AES.MODE_CBC, iv)
  ciphertext = cipher.encrypt(pad(bytes(value, encoding='utf8'), size))
  return iv + ciphertext

Non compliant code​

The application uses insecure encryption algorithms

from Crypto import Random
from Crypto.Cipher import AES
from Crypto.Util.Padding import paddef encrypt(value, key):
  value = value.encode('ascii')
  iv = "HardCodedValue"
  cipher = AES.new(key, AES.MODE_CBC, iv)
  ciphertext = cipher.encrypt(pad(bytes(value, encoding='utf8'), size))
  return iv + ciphertext

Requirements​

free trial

Search for vulnerabilities in your apps for free with our automated security testing! Start your 21-day free trial and discover the benefits of our Continuous Hacking Machine Plan. If you prefer a full service that includes the expertise of our ethical hackers, don't hesitate to contact us for our Continuous Hacking Squad Plan.