Selection of Less-Secure Algorithm During Negotiation ('Algorithm Downgrade') (4.16) (original) (raw)
| CWE Glossary Definition |  |
|---|---|
Weakness ID: 757
Vulnerability Mapping: ALLOWED This CWE ID may be used to map to real-world vulnerabilities
Abstraction:Base 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.
Description
A protocol or its implementation supports interaction between multiple actors and allows those actors to negotiate which algorithm should be used as a protection mechanism such as encryption or authentication, but it does not select the strongest algorithm that is available to both parties.
Extended Description
When a security mechanism can be forced to downgrade to use a less secure algorithm, this can make it easier for attackers to compromise the product by exploiting weaker algorithm. The victim might not be aware that the less secure algorithm is being used. For example, if an attacker can force a communications channel to use cleartext instead of strongly-encrypted data, then the attacker could read the channel by sniffing, instead of going through extra effort of trying to decrypt the data using brute force techniques.
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 |
|---|---|---|
| Access Control | Technical Impact: Bypass Protection Mechanism |
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)
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. |
1013 | Encrypt Data |
Modes Of Introduction
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. |
Observed Examples
| Reference | Description |
|---|---|
| CVE-2006-4302 | Attacker can select an older version of the software to exploit its vulnerabilities. |
| CVE-2006-4407 | Improper prioritization of encryption ciphers during negotiation leads to use of a weaker cipher. |
| CVE-2005-2969 | chain: SSL/TLS implementation disables a verification step (CWE-325) that enables a downgrade attack to a weaker protocol. |
| CVE-2001-1444 | Telnet protocol implementation allows downgrade to weaker authentication and encryption using an Adversary-in-the-Middle AITM attack. |
| CVE-2002-1646 | SSH server implementation allows override of configuration setting to use weaker authentication schemes. This may be a composite with CWE-642. |
Detection Methods
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.)
Effectiveness: High
Memberships
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.
Vulnerability Mapping Notes
| Usage: ALLOWED (this CWE ID may be used to map to real-world vulnerabilities) |
|---|
| Reason: Acceptable-Use |
| Rationale: This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities. |
| Comments: Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction. |
Notes
Relationship
This is related to CWE-300, although not all downgrade attacks necessarily require an entity that redirects or interferes with the network. See examples.
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