CWE-93: Improper Neutralization of CRLF Sequences ('CRLF Injection') Weakness ID: 93 Vulnerability Mapping:
ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities Abstraction: BaseBase - 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 The product uses CRLF (carriage return line feeds) as a special element, e.g. to separate lines or records, but it does not neutralize or incorrectly neutralizes CRLF sequences from inputs. 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 |
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Integrity
| Technical Impact: Modify Application Data | |
Potential Mitigations
Phase: Implementation Avoid using CRLF as a special sequence. |
Phase: Implementation Appropriately filter or quote CRLF sequences in user-controlled input. |
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 |
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ChildOf | 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. | 74 | Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection') | ParentOf | 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. | 113 | Improper Neutralization of CRLF Sequences in HTTP Headers ('HTTP Request/Response Splitting') | CanPrecede | 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. | 117 | Improper Output Neutralization for Logs |
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 "Software Development" (CWE-699) Nature | Type | ID | Name |
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MemberOf | Category - a CWE entry that contains a set of other entries that share a common characteristic. | 137 | Data Neutralization Issues |
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 |
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MemberOf | Category - a CWE entry that contains a set of other entries that share a common characteristic. | 1019 | Validate Inputs |
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 |
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Implementation | REALIZATION: This weakness is caused during implementation of an architectural security tactic. |
Demonstrative Examples Example 1 If user input data that eventually makes it to a log message isn't checked for CRLF characters, it may be possible for an attacker to forge entries in a log file. (bad code) Example Language: Java
logger.info("User's street address: " + request.getParameter("streetAddress"));
Observed Examples Reference | Description |
| CRLF injection enables spam proxy (add mail headers) using email address or name. |
| CRLF injection in API function arguments modify headers for outgoing requests. |
| Spoofed entries in web server log file via carriage returns |
| Chain: inject fake log entries with fake timestamps using CRLF injection |
| Chain: Application accepts CRLF in an object ID, allowing HTTP response splitting. |
| Chain: HTTP response splitting via CRLF in parameter related to URL. |
Weakness Ordinalities Ordinality | Description |
Primary | (where the weakness exists independent of other weaknesses) |
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.) |
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 could 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. |
Taxonomy Mappings Mapped Taxonomy Name | Node ID | Fit | Mapped Node Name |
PLOVER | | | CRLF Injection |
OWASP Top Ten 2007 | A2 | CWE More Specific | Injection Flaws |
WASC | 24 | | HTTP Request Splitting |
Software Fault Patterns | SFP24 | | Tainted input to command |
References Content History Submissions |
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Submission Date | Submitter | Organization |
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2006-07-19 (CWE Draft 3, 2006-07-19) | PLOVER | | | Modifications |
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Modification Date | Modifier | Organization |
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2008-07-01 | Sean Eidemiller | Cigital | added/updated demonstrative examples | 2008-07-01 | Eric Dalci | Cigital | updated Time_of_Introduction | 2008-09-08 | CWE Content Team | MITRE | updated Relationships, Other_Notes, Taxonomy_Mappings, Weakness_Ordinalities | 2009-03-10 | CWE Content Team | MITRE | updated References | 2009-05-27 | CWE Content Team | MITRE | updated Name | 2009-10-29 | CWE Content Team | MITRE | updated Other_Notes | 2009-12-28 | CWE Content Team | MITRE | updated Likelihood_of_Exploit | 2010-02-16 | CWE Content Team | MITRE | updated Related_Attack_Patterns, Taxonomy_Mappings | 2010-04-05 | CWE Content Team | MITRE | updated Related_Attack_Patterns | 2010-06-21 | CWE Content Team | MITRE | updated Description, Name | 2011-03-29 | CWE Content Team | MITRE | updated Description | 2011-06-01 | CWE Content Team | MITRE | updated Common_Consequences | 2012-05-11 | CWE Content Team | MITRE | updated Relationships | 2012-10-30 | CWE Content Team | MITRE | updated Potential_Mitigations | 2014-07-30 | CWE Content Team | MITRE | updated Relationships, Taxonomy_Mappings | 2015-12-07 | CWE Content Team | MITRE | updated Relationships | 2017-11-08 | CWE Content Team | MITRE | updated Applicable_Platforms, Causal_Nature, Likelihood_of_Exploit, Modes_of_Introduction, References, Relationships | 2019-06-20 | CWE Content Team | MITRE | updated Relationships | 2020-02-24 | CWE Content Team | MITRE | updated Relationships | 2021-10-28 | CWE Content Team | MITRE | updated Relationships | 2022-04-28 | CWE Content Team | MITRE | updated Research_Gaps | 2023-01-31 | CWE Content Team | MITRE | updated Description | 2023-04-27 | CWE Content Team | MITRE | updated Detection_Factors, Relationships, Time_of_Introduction | 2023-06-29 | CWE Content Team | MITRE | updated Mapping_Notes | Previous Entry Names |
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Change Date | Previous Entry Name |
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2008-04-11 | CRLF Injection | | 2009-05-27 | Failure to Sanitize CRLF Sequences (aka 'CRLF Injection') | | 2010-06-21 | Failure to Sanitize CRLF Sequences ('CRLF Injection') | |
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