CWE-327: Use of a Broken or Risky Cryptographic Algorithm
Weakness ID: 327
Vulnerability Mapping:
ALLOWEDThis CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review (with careful review of mapping notes) Abstraction: ClassClass - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
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Description
The product uses a broken or risky cryptographic algorithm or protocol.
Extended Description
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.
Common Consequences
This table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Scope
Impact
Likelihood
Confidentiality
Technical Impact: Read Application Data
The confidentiality of sensitive data may be compromised by the use of a broken or risky cryptographic algorithm.
Integrity
Technical Impact: Modify Application Data
The integrity of sensitive data may be compromised by the use of a broken or risky cryptographic algorithm.
Accountability Non-Repudiation
Technical Impact: Hide Activities
If the cryptographic algorithm is used to ensure the identity of the source of the data (such as digital signatures), then a broken algorithm will compromise this scheme and the source of the data cannot be proven.
Potential Mitigations
Phase: Architecture and Design
Strategy: Libraries or Frameworks
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]
Phase: 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.
Effectiveness: Defense in Depth
Phase: 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.
Phase: Architecture and Design
Strategy: Libraries or Frameworks
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.
Relationships
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Research Concepts" (CWE-1000)
Nature
Type
ID
Name
ChildOf
Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things.
Base - a weakness
that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
Variant - a weakness
that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
Base - a weakness
that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
Base - a weakness
that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
Base - a weakness
that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
Nature
Type
ID
Name
MemberOf
View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).
Base - a weakness
that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Architectural Concepts" (CWE-1008)
Nature
Type
ID
Name
MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.
The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
Phase
Note
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
This listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.
Languages
Class: Not Language-Specific (Undetermined Prevalence)
Verilog (Undetermined Prevalence)
VHDL (Undetermined Prevalence)
Technologies
Class: Not Technology-Specific (Undetermined Prevalence)
Class: ICS/OT (Undetermined Prevalence)
Likelihood Of Exploit
High
Demonstrative Examples
Example 1
These code examples use the Data Encryption Standard (DES).
Once considered a strong algorithm, DES now regarded as insufficient for many applications. It has been replaced by Advanced Encryption Standard (AES).
Example 2
Suppose a chip manufacturer decides to implement a hashing scheme for verifying integrity property of certain bitstream, and it chooses to implement a SHA1 hardware accelerator for to implement the scheme.
(bad code)
Example Language: Other
The manufacturer chooses a SHA1 hardware accelerator for to implement the scheme because it already has a working SHA1 Intellectual Property (IP) that the manufacturer had created and used earlier, so this reuse of IP saves design cost.
However, SHA1 was theoretically broken in 2005 and practically broken in 2017 at a cost of $110K. This means an attacker with access to cloud-rented computing power will now be able to provide a malicious bitstream with the same hash value, thereby defeating the purpose for which the hash was used.
This issue could have been avoided with better design.
(good code)
Example Language: Other
The manufacturer could have chosen a cryptographic solution that is recommended by the wide security community (including standard-setting bodies like NIST) and is not expected to be broken (or even better, weakened) within the reasonable life expectancy of the hardware product. In this case, the architects could have used SHA-2 or SHA-3, even if it meant that such choice would cost extra.
Example 3
In 2022, the OT:ICEFALL study examined products by 10 different Operational Technology (OT) vendors. The researchers reported 56 vulnerabilities and said that the products were "insecure by design" [REF-1283]. If exploited, these vulnerabilities often allowed adversaries to change how the products operated, ranging from denial of service to changing the code that the products executed. Since these products were often used in industries such as power, electrical, water, and others, there could even be safety implications.
SCADA-based protocol supports a legacy encryption mode that uses Tiny Encryption Algorithm (TEA) in ECB mode, which leaks patterns in messages and cannot protect integrity
Product uses the hash of a hash for authentication, allowing attackers to gain privileges if they can obtain the original hash.
Detection Methods
Automated Analysis
Automated methods may be useful for recognizing commonly-used libraries or features that have become obsolete.
Effectiveness: Moderate
Note: False negatives may occur if the tool is not aware of the cryptographic libraries in use, or if custom cryptography is being used.
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.
Note: These may be more effective than strictly automated techniques. This is especially the case with weaknesses that are related to design and business rules.
Automated Static Analysis - Binary or Bytecode
According to SOAR, the following detection techniques may be useful:
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
Nature
Type
ID
Name
MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.
View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).
(this CWE ID could be used to map to real-world vulnerabilities in limited situations requiring careful review)
Reason: Abstraction
Rationale:
This CWE entry is a Class and might have Base-level children that would be more appropriate
Comments:
Examine children of this entry to see if there is a better fit
Notes
Maintenance
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.
Maintenance
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.
Taxonomy Mappings
Mapped Taxonomy Name
Node ID
Fit
Mapped Node Name
CLASP
Using a broken or risky cryptographic algorithm
OWASP Top Ten 2004
A8
CWE More Specific
Insecure Storage
CERT C Secure Coding
MSC30-C
CWE More Abstract
Do not use the rand() function for generating pseudorandom numbers
CERT C Secure Coding
MSC32-C
CWE More Abstract
Properly seed pseudorandom number generators
The CERT Oracle Secure Coding Standard for Java (2011)
[REF-281] Alfred J. Menezes, Paul C. van Oorschot
and Scott A. Vanstone. "Handbook of Applied Cryptography". 1996-10.
<https://cacr.uwaterloo.ca/hac/>. URL validated: 2023-04-07.
[REF-44] Michael Howard, David LeBlanc
and John Viega. "24 Deadly Sins of Software Security". "Sin 21: Using the Wrong Cryptography." Page 315. McGraw-Hill. 2010.
[REF-62] Mark Dowd, John McDonald
and Justin Schuh. "The Art of Software Security Assessment". Chapter 2, "Insufficient or Obsolete Encryption", Page 44. 1st Edition. Addison Wesley. 2006.
[REF-1192] Information Technology Laboratory, National Institute of Standards and Technology. "FIPS PUB 140-3: SECURITY REQUIREMENTS FOR CRYPTOGRAPHIC MODULES". 2019-03-22.
<https://csrc.nist.gov/publications/detail/fips/140/3/final>.
Provide a hardware-specific submission whose contents were integrated into this entry, affecting extended description, applicable platforms, demonstrative examples, and mitigations