CWE-327 Detail

The product uses a broken or risky cryptographic algorithm or protocol.

Cryptographic algorithms are the methods by which data is scrambled to prevent observation or influence by unauthorized actors. Insecure cryptography can be exploited to expose sensitive information, modify data in unexpected ways, spoof identities of other users or devices, or other impacts.

It is very difficult to produce a secure algorithm, and even high-profile algorithms by accomplished cryptographic experts have been broken. Well-known techniques exist to break or weaken various kinds of cryptography. Accordingly, there are a small number of well-understood and heavily studied algorithms that should be used by most products. Using a non-standard or known-insecure algorithm is dangerous because a determined adversary may be able to break the algorithm and compromise whatever data has been protected.

Since the state of cryptography advances so rapidly, it is common for an algorithm to be considered "unsafe" even if it was once thought to be strong. This can happen when new attacks are discovered, or if computing power increases so much that the cryptographic algorithm no longer provides the amount of protection that was originally thought.

For a number of reasons, this weakness is even more challenging to manage with hardware deployment of cryptographic algorithms as opposed to software implementation. First, if a flaw is discovered with hardware-implemented cryptography, the flaw cannot be fixed in most cases without a recall of the product, because hardware is not easily replaceable like software. Second, because the hardware product is expected to work for years, the adversary's computing power will only increase over time.

Modes Of Introduction

Architecture and Design : COMMISSION: This weakness refers to an incorrect design related to an architectural security tactic.
Implementation : With hardware, the Architecture or Design Phase might start with compliant cryptography, but it is replaced with a non-compliant crypto during the later Implementation phase due to implementation constraints (e.g., not enough entropy to make it function properly, or not enough silicon real estate available to implement). Or, in rare cases (especially for long projects that span over years), the Architecture specifications might start with cryptography that was originally compliant at the time the Architectural specs were written, but over the time it became non-compliant due to progress made in attacking the crypto.

Applicable Platforms

Language

Class: Not Language-Specific (Undetermined)
Name: Verilog (Undetermined)
Name: VHDL (Undetermined)

Technologies

Class: Not Technology-Specific (Undetermined)
Class: ICS/OT (Undetermined)

Common Consequences

Observed Examples

Potential Mitigations

Phases : Architecture and Design

When there is a need to store or transmit sensitive data, use strong, up-to-date cryptographic algorithms to encrypt that data. Select a well-vetted algorithm that is currently considered to be strong by experts in the field, and use well-tested implementations. As with all cryptographic mechanisms, the source code should be available for analysis.

For example, US government systems require FIPS 140-2 certification [REF-1192].

Do not develop custom or private cryptographic algorithms. They will likely be exposed to attacks that are well-understood by cryptographers. Reverse engineering techniques are mature. If the algorithm can be compromised if attackers find out how it works, then it is especially weak.

Periodically ensure that the cryptography has not become obsolete. Some older algorithms, once thought to require a billion years of computing time, can now be broken in days or hours. This includes MD4, MD5, SHA1, DES, and other algorithms that were once regarded as strong. [REF-267]

Phases : Architecture and Design
Ensure that the design allows one cryptographic algorithm to be replaced with another in the next generation or version. Where possible, use wrappers to make the interfaces uniform. This will make it easier to upgrade to stronger algorithms. With hardware, design the product at the Intellectual Property (IP) level so that one cryptographic algorithm can be replaced with another in the next generation of the hardware product.
Phases : Architecture and Design
Carefully manage and protect cryptographic keys (see CWE-320). If the keys can be guessed or stolen, then the strength of the cryptography itself is irrelevant.
Phases : Architecture and Design

Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid.

Industry-standard implementations will save development time and may be more likely to avoid errors that can occur during implementation of cryptographic algorithms. Consider the ESAPI Encryption feature.

Phases : Implementation // Architecture and Design
When using industry-approved techniques, use them correctly. Don't cut corners by skipping resource-intensive steps (CWE-325). These steps are often essential for preventing common attacks.

Detection Methods

Automated Analysis

Automated methods may be useful for recognizing commonly-used libraries or features that have become obsolete.
Effectiveness : Moderate

Manual Analysis

This weakness can be detected using tools and techniques that require manual (human) analysis, such as penetration testing, threat modeling, and interactive tools that allow the tester to record and modify an active session.

Automated Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Effectiveness : SOAR Partial

Manual Static Analysis - Binary or Bytecode

According to SOAR, the following detection techniques may be useful:

Effectiveness : SOAR Partial

Dynamic Analysis with Automated Results Interpretation

According to SOAR, the following detection techniques may be useful:

Effectiveness : SOAR Partial

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Effectiveness : High

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Effectiveness : High

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Effectiveness : High

Automated Static Analysis

According to SOAR, the following detection techniques may be useful:

Effectiveness : SOAR Partial

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Effectiveness : High

Vulnerability Mapping Notes

Justification : This CWE entry is a Class and might have Base-level children that would be more appropriate
Comment : Examine children of this entry to see if there is a better fit

Related Attack Patterns

NotesNotes

Since CWE 4.4, various cryptography-related entries, including CWE-327 and CWE-1240, have been slated for extensive research, analysis, and community consultation to define consistent terminology, improve relationships, and reduce overlap or duplication. As of CWE 4.6, this work is still ongoing.
The Taxonomy_Mappings to ISA/IEC 62443 were added in CWE 4.10, but they are still under review and might change in future CWE versions. These draft mappings were performed by members of the "Mapping CWE to 62443" subgroup of the CWE-CAPEC ICS/OT Special Interest Group (SIG), and their work is incomplete as of CWE 4.10. The mappings are included to facilitate discussion and review by the broader ICS/OT community, and they are likely to change in future CWE versions.

References

REF-280

Applied Cryptography
Bruce Schneier.
https://www.schneier.com/books/applied-cryptography

REF-281

Handbook of Applied Cryptography
Alfred J. Menezes, Paul C. van Oorschot, Scott A. Vanstone.
https://cacr.uwaterloo.ca/hac/

REF-282

Avoiding bogus encryption products: Snake Oil FAQ
C Matthew Curtin.
http://www.faqs.org/faqs/cryptography-faq/snake-oil/

REF-267

SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES
Information Technology Laboratory, National Institute of Standards and Technology.
https://csrc.nist.gov/csrc/media/publications/fips/140/2/final/documents/fips1402.pdf

REF-284

Microsoft Scraps Old Encryption in New Code
Paul F. Roberts.
https://www.eweek.com/security/microsoft-scraps-old-encryption-in-new-code/

REF-7

Writing Secure Code
Michael Howard, David LeBlanc.
https://www.microsoftpressstore.com/store/writing-secure-code-9780735617223

REF-44

24 Deadly Sins of Software Security
Michael Howard, David LeBlanc, John Viega.

REF-287

Top 25 Series - Rank 24 - Use of a Broken or Risky Cryptographic Algorithm
Johannes Ullrich.
https://www.sans.org/blog/top-25-series-use-of-a-broken-or-risky-cryptographic-algorithm/

REF-62

The Art of Software Security Assessment
Mark Dowd, John McDonald, Justin Schuh.

REF-962

Automated Source Code Security Measure (ASCSM)
Object Management Group (OMG).
http://www.omg.org/spec/ASCSM/1.0/

REF-18

The CLASP Application Security Process
Secure Software, Inc..
https://cwe.mitre.org/documents/sources/TheCLASPApplicationSecurityProcess.pdf

REF-1192

FIPS PUB 140-3: SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES
Information Technology Laboratory, National Institute of Standards and Technology.
https://csrc.nist.gov/publications/detail/fips/140/3/final

REF-1283

OT:ICEFALL: The legacy of "insecure by design" and its implications for certifications and risk management
Forescout Vedere Labs.
https://www.forescout.com/resources/ot-icefall-report/

Submission

Modifications