Predictable from Observable State

Opis

A number or object is predictable based on observations that the attacker can make about the state of the system or network, such as time, process ID, etc.

Skutki

• Other

  Varies by Context

  This weakness could be exploited by an attacker in a number ways depending on the context. If a predictable number is used to generate IDs or keys that are used within protection mechanisms, then an attacker could gain unauthorized access to the system. If predictable filenames are used for storing sensitive information, then an attacker might gain access to the system and may be able to gain access to the information in the file.

Zapobieganie

• Implementation

  Increase the entropy used to seed a PRNG.

• Architecture and Design, Requirements · Libraries or Frameworks

  Use products or modules that conform to FIPS 140-2 [REF-267] to avoid obvious entropy problems. Consult FIPS 140-2 Annex C ("Approved Random Number Generators").

• Implementation

  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.

Przykłady podatności

• CVE-2024-48445 Chain: e-commerce app relies on an easily-guessable timestamp (CWE-341) in a weak authentication algorithm (CWE-1390)
• CVE-2002-0389 Mail server stores private mail messages with predictable filenames in a world-executable directory, which allows local users to read private mailing list archives.
• CVE-2001-1141 PRNG allows attackers to use the output of small PRNG requests to determine the internal state information, which could be used by attackers to predict future pseudo-random numbers.
• CVE-2000-0335 DNS resolver library uses predictable IDs, which allows a local attacker to spoof DNS query results.
• CVE-2005-1636 MFV. predictable filename and insecure permissions allows file modification to execute SQL queries.

Słabość nadrzędna

• CWE-340 Generation of Predictable Numbers or Identifiers

Kiedy powstaje

• Architecture and Design
• 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, 2001
2. 24 Deadly Sins of Software Security — Michael Howard, David LeBlanc, John Viega, "Sin 20: Weak Random Numbers." Page 299, McGraw-Hill, 2010