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 prepares a structured message for communication with another component, but encoding or escaping of the data is either missing or done incorrectly. As a result, the intended structure of the message is not preserved.
Extended Description
Improper encoding or escaping can allow attackers to change the commands that are sent to another component, inserting malicious commands instead.
Most products follow a certain protocol that uses structured messages for communication between components, such as queries or commands. These structured messages can contain raw data interspersed with metadata or control information. For example, "GET /index.html HTTP/1.1" is a structured message containing a command ("GET") with a single argument ("/index.html") and metadata about which protocol version is being used ("HTTP/1.1").
If an application uses attacker-supplied inputs to construct a structured message without properly encoding or escaping, then the attacker could insert special characters that will cause the data to be interpreted as control information or metadata. Consequently, the component that receives the output will perform the wrong operations, or otherwise interpret the data incorrectly.
Alternate Terms
Output Sanitization
Output Validation
Output Encoding
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.
Impact
Details
Modify Application Data
Scope: Integrity
The communications between components can be modified in unexpected ways. Unexpected commands can be executed, bypassing other security mechanisms. Incoming data can be misinterpreted.
Execute Unauthorized Code or Commands
Scope: Integrity, Confidentiality, Availability, Access Control
The communications between components can be modified in unexpected ways. Unexpected commands can be executed, bypassing other security mechanisms. Incoming data can be misinterpreted.
Bypass Protection Mechanism
Scope: Confidentiality
The communications between components can be modified in unexpected ways. Unexpected commands can be executed, bypassing other security mechanisms. Incoming data can be misinterpreted.
Potential Mitigations
Phase(s)
Mitigation
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.
For example, consider using the ESAPI Encoding control [REF-45] or a similar tool, library, or framework. These will help the programmer encode outputs in a manner less prone to error.
Alternately, use built-in functions, but consider using wrappers in case those functions are discovered to have a vulnerability.
Architecture and Design
Strategy: Parameterization
If available, use structured mechanisms that automatically enforce the separation between data and code. These mechanisms may be able to provide the relevant quoting, encoding, and validation automatically, instead of relying on the developer to provide this capability at every point where output is generated.
For example, stored procedures can enforce database query structure and reduce the likelihood of SQL injection.
Architecture and Design; Implementation
Understand the context in which your data will be used and the encoding that will be expected. This is especially important when transmitting data between different components, or when generating outputs that can contain multiple encodings at the same time, such as web pages or multi-part mail messages. Study all expected communication protocols and data representations to determine the required encoding strategies.
Architecture and Design
In some cases, input validation may be an important strategy when output encoding is not a complete solution. For example, you may be providing the same output that will be processed by multiple consumers that use different encodings or representations. In other cases, you may be required to allow user-supplied input to contain control information, such as limited HTML tags that support formatting in a wiki or bulletin board. When this type of requirement must be met, use an extremely strict allowlist to limit which control sequences can be used. Verify that the resulting syntactic structure is what you expect. Use your normal encoding methods for the remainder of the input.
Architecture and Design
Use input validation as a defense-in-depth measure to reduce the likelihood of output encoding errors (see CWE-20).
Requirements
Fully specify which encodings are required by components that will be communicating with each other.
Implementation
When exchanging data between components, ensure that both components are using the same character encoding. Ensure that the proper encoding is applied at each interface. Explicitly set the encoding you are using whenever the protocol allows you to do so.
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" (View-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.
Improper Neutralization of HTTP Headers for Scripting Syntax
ParentOf
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.
Improper Neutralization of Special Elements in Output Used by a Downstream Component ('Injection')
Relevant to the view "Weaknesses for Simplified Mapping of Published Vulnerabilities" (View-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).
Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf
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.
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
Implementation
Operation
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
(Often Prevalent)
Technologies
Class: Not Technology-Specific
(Undetermined Prevalence)
AI/ML
(Undetermined Prevalence)
Database Server
(Often Prevalent)
Web Server
(Often Prevalent)
Likelihood Of Exploit
High
Demonstrative Examples
Example 1
This code displays an email address that was submitted as part of a form.
The value read from the form parameter is reflected back to the client browser without having been encoded prior to output, allowing various XSS attacks (CWE-79).
Example 2
Consider a chat application in which a front-end web application communicates with a back-end server. The back-end is legacy code that does not perform authentication or authorization, so the front-end must implement it. The chat protocol supports two commands, SAY and BAN, although only administrators can use the BAN command. Each argument must be separated by a single space. The raw inputs are URL-encoded. The messaging protocol allows multiple commands to be specified on the same line if they are separated by a "|" character.
First let's look at the back end command processor code
(bad code)
Example Language: Perl
$inputString = readLineFromFileHandle($serverFH);
# generate an array of strings separated by the "|" character. @commands = split(/\|/, $inputString);
Description
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.
