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Description
The software receives input from an upstream component, but it does not neutralize or incorrectly neutralizes special elements that could be interpreted as variable name delimiters when they are sent to a downstream component.
As data is parsed, an injected delimiter may cause the process to take unexpected actions that result in an attack. Example: “$” for an environment variable.
Modes of Introduction:
– Implementation
Related Weaknesses
CWE-138
Consequences
Integrity: Unexpected State
Potential Mitigations
Phase:
Description:
Developers should anticipate that variable name delimiters will be injected/removed/manipulated in the input vectors of their software system. Use an appropriate combination of denylists and allowlists to ensure only valid, expected and appropriate input is processed by the system.
Phase: Implementation
Description:
Phase: Implementation
Description:
While it is risky to use dynamically-generated query strings, code, or commands that mix control and data together, sometimes it may be unavoidable. Properly quote arguments and escape any special characters within those arguments. The most conservative approach is to escape or filter all characters that do not pass an extremely strict allowlist (such as everything that is not alphanumeric or white space). If some special characters are still needed, such as white space, wrap each argument in quotes after the escaping/filtering step. Be careful of argument injection (CWE-88).
Phase: Implementation
Description:
Inputs should be decoded and canonicalized to the application’s current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass allowlist validation schemes by introducing dangerous inputs after they have been checked.
CVE References
- CVE-2005-0129
- “%” variable is expanded by wildcard function into disallowed commands.
- CVE-2002-0770
- Server trusts client to expand macros, allows macro characters to be expanded to trigger resultant information exposure.
