Description
The software 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.
Modes of Introduction:
– Architecture and Design
Likelihood of Exploit: High
Related Weaknesses
Consequences
Integrity: Modify Application Data
The communications between components can be modified in unexpected ways. Unexpected commands can be executed, bypassing other security mechanisms. Incoming data can be misinterpreted.
Integrity, Confidentiality, Availability, Access Control: Execute Unauthorized Code or Commands
The communications between components can be modified in unexpected ways. Unexpected commands can be executed, bypassing other security mechanisms. Incoming data can be misinterpreted.
Confidentiality: Bypass Protection Mechanism
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: Architecture and Design
Description:
Phase: Architecture and Design
Description:
Phase: Architecture and Design, Implementation
Description:
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.
Phase: Architecture and Design
Description:
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.
Phase: Architecture and Design
Description:
Use input validation as a defense-in-depth measure to reduce the likelihood of output encoding errors (see CWE-20).
Phase: Requirements
Description:
Fully specify which encodings are required by components that will be communicating with each other.
Phase: Implementation
Description:
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.
CVE References
- CVE-2008-4636
- OS command injection in backup software using shell metacharacters in a filename; correct behavior would require that this filename could not be changed.
- CVE-2008-0769
- Web application does not set the charset when sending a page to a browser, allowing for XSS exploitation when a browser chooses an unexpected encoding.
- CVE-2008-0005
- Program does not set the charset when sending a page to a browser, allowing for XSS exploitation when a browser chooses an unexpected encoding.
- CVE-2008-5573
- SQL injection via password parameter; a strong password might contain “&”
- CVE-2008-3773
- Cross-site scripting in chat application via a message subject, which normally might contain “&” and other XSS-related characters.
- CVE-2008-0757
- Cross-site scripting in chat application via a message, which normally might be allowed to contain arbitrary content.