COMMON WEAKNESS ENUMERATIONDraft

CWE-337

Predictable Seed in Pseudo-Random Number Generator (PRNG)

A Pseudo-Random Number Generator (PRNG) is initialized from a predictable seed, such as the process ID or system time.

Soyutlama

Variant

Yapı

Simple

Sömürü İhtimali

Medium

Problemi anla

Problem nedir?

A Pseudo-Random Number Generator (PRNG) is initialized from a predictable seed, such as the process ID or system time.

Genişletilmiş açıklama

The use of predictable seeds significantly reduces the number of possible seeds that an attacker would need to test in order to predict which random numbers will be generated by the PRNG.

Kök neden

Problem nasıl ve ne zaman oluşur?

Yaşam döngüsü evresi

Implementation

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

Risk

Başarılı sömürü neye yol açar?

Varies by Context

Etkilenen güvenlik alanları: Other

Savunma

Nasıl önlenir ve çözülür?

Tüm evreler

Genel azaltım ve savunma yaklaşımı

Detay
Use non-predictable inputs for seed generation.

Architecture and Design · Requirements

Libraries or Frameworks

Detay
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.

Implementation

Uygulama aşaması savunması

Detay
Use a PRNG that periodically re-seeds itself using input from high-quality sources, such as hardware devices with high entropy. However, do not re-seed too frequently, or else the entropy source might block.

Doğrulama

Nasıl tespit edilir?

Automated Static Analysis

Automated static analysis, commonly referred to as Static Application Security Testing (SAST), can find some instances of this weakness by analyzing source code (or binary/compiled code) without having to execute it. Typically, this is done by building a model of data flow and control flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input) with "sinks" (destinations where the data interacts with external components, a lower layer such as the OS, etc.)