CWE

Common Weakness Enumeration

A community-developed list of SW & HW weaknesses that can become vulnerabilities

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ID

CWE-181: Incorrect Behavior Order: Validate Before Filter

Weakness ID: 181
Vulnerability Mapping: ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities
Abstraction: VariantVariant - 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.
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+ Description
The product validates data before it has been filtered, which prevents the product from detecting data that becomes invalid after the filtering step.
+ Extended Description
This can be used by an attacker to bypass the validation and launch attacks that expose weaknesses that would otherwise be prevented, such as injection.
+ Alternate Terms
Validate-before-cleanse
+ Common Consequences
Section HelpThis 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.
ScopeImpactLikelihood
Access Control

Technical Impact: Bypass Protection Mechanism

+ Potential Mitigations

Phases: Implementation; Architecture and Design

Inputs should be decoded and canonicalized to the application's current internal representation before being filtered.
+ Relationships
Section HelpThis 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)
NatureTypeIDName
ChildOfBaseBase - 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.179Incorrect Behavior Order: Early Validation
+ Modes Of Introduction
Section HelpThe 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.
PhaseNote
Implementation
+ Applicable Platforms
Section HelpThis 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)

+ Demonstrative Examples

Example 1

This script creates a subdirectory within a user directory and sets the user as the owner.

(bad code)
Example Language: PHP 
function createDir($userName,$dirName){
$userDir = '/users/'. $userName;
if(strpos($dirName,'..') !== false){
echo 'Directory name contains invalid sequence';
return;
}
//filter out '~' because other scripts identify user directories by this prefix
$dirName = str_replace('~','',$dirName);
$newDir = $userDir . $dirName;
mkdir($newDir, 0700);
chown($newDir,$userName);
}

While the script attempts to screen for '..' sequences, an attacker can submit a directory path including ".~.", which will then become ".." after the filtering step. This allows a Path Traversal (CWE-21) attack to occur.


+ Observed Examples
ReferenceDescription
Directory traversal vulnerability allows remote attackers to read or modify arbitrary files via invalid characters between two . (dot) characters, which are filtered and result in a ".." sequence.
Directory traversal vulnerability allows attackers to overwrite arbitrary files via invalid characters between two . (dot) characters, which are filtered and result in a ".." sequence.
+ Functional Areas
  • Protection Mechanism
+ Memberships
Section HelpThis 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.
NatureTypeIDName
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.722OWASP Top Ten 2004 Category A1 - Unvalidated Input
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.992SFP Secondary Cluster: Faulty Input Transformation
MemberOfCategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic.1410Comprehensive Categorization: Insufficient Control Flow Management
+ 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 Variant 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

Research Gap

This category is probably under-studied.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERValidate-Before-Filter
OWASP Top Ten 2004A1CWE More SpecificUnvalidated Input
+ Content History
+ Submissions
Submission DateSubmitterOrganization
2006-07-19
(CWE Draft 3, 2006-07-19)
PLOVER
+ Modifications
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-08-15Veracode
Suggested OWASP Top Ten 2004 mapping
2008-09-08CWE Content TeamMITRE
updated Functional_Areas, Relationships, Research_Gaps, Taxonomy_Mappings, Type
2008-10-14CWE Content TeamMITRE
updated Description
2010-06-21CWE Content TeamMITRE
updated Description, Observed_Examples
2011-03-29CWE Content TeamMITRE
updated Demonstrative_Examples
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated Demonstrative_Examples, Observed_Examples, Related_Attack_Patterns, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships
2017-01-19CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms
2019-01-03CWE Content TeamMITRE
updated Related_Attack_Patterns
2020-02-24CWE Content TeamMITRE
updated Relationships, Type
2023-01-31CWE Content TeamMITRE
updated Description
2023-04-27CWE Content TeamMITRE
updated Relationships
2023-06-29CWE Content TeamMITRE
updated Mapping_Notes
+ Previous Entry Names
Change DatePrevious Entry Name
2008-04-11Validate-before-filter
Page Last Updated: July 16, 2024