Same Seed in Pseudo-Random Number Generator (PRNG)

Opis

A Pseudo-Random Number Generator (PRNG) uses the same seed each time the product is initialized.

Given the deterministic nature of PRNGs, using the same seed for each initialization will lead to the same output in the same order. If an attacker can guess (or knows) the seed, then the attacker may be able to determine the random numbers that will be produced from the PRNG.

Skutki

• Other, Access Control

  Other; Bypass Protection Mechanism

Zapobieganie

• Architecture and Design

  Do not reuse PRNG seeds. Consider a PRNG that periodically re-seeds itself as needed from a high quality pseudo-random output, such as hardware devices.

• Architecture and Design, Requirements · Libraries or Frameworks

  Use products or modules that conform to FIPS 140-2 [REF-267] to avoid obvious entropy problems, or use the more recent FIPS 140-3 [REF-1192] if possible.

Przykłady podatności

• CVE-2022-39218 SDK for JavaScript app builder for serverless code uses the same fixed seed for a PRNG, allowing cryptography bypass

Słabość nadrzędna

• CWE-335 Incorrect Usage of Seeds in Pseudo-Random Number Generator (PRNG)

Kiedy powstaje

• Implementation — REALIZATION: This weakness is caused during implementation of an architectural security tactic.

Dotyczy

Not Language-Specific

Uwagi

As of CWE 4.5, terminology related to randomness, entropy, and predictability can vary widely. Within the developer and other communities, "randomness" is used heavily. However, within cryptography, "entropy" is distinct, typically implied as a measurement. There are no commonly-used definitions, even within standards documents and cryptography papers. Future versions of CWE will attempt to define these terms and, if necessary, distinguish between them in ways that are appropriate for different communities but do not reduce the usability of CWE for mapping, understanding, or other scenarios.

Źródła

1. FIPS PUB 140-2: SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES — Information Technology Laboratory, National Institute of Standards and Technology, Annex C, Approved Random Number Generators, 2001
2. FIPS PUB 140-3: SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES — Information Technology Laboratory, National Institute of Standards and Technology, 2019