Improper Neutralization of Variable Name DelimitersID: 154 | Date: (C)2012-05-14 (M)2022-10-10 |
Type: weakness | Status: INCOMPLETE |
Abstraction Type: Variant |
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.
Extended DescriptionAs data is parsed, an injected delimiter may cause the process to take
unexpected actions that result in an attack. Example: "$" for an environment
variable.
Applicable PlatformsLanguage Class: All
Time Of Introduction
Related Attack Patterns
Common Consequences
Scope | Technical Impact | Notes |
---|
Integrity | Unexpected state | |
Detection MethodsNone
Potential Mitigations
Phase | Strategy | Description | Effectiveness | Notes |
---|
| | 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 black lists and white lists to
ensure only valid, expected and appropriate input is processed by the
system. | | |
Implementation | Input Validation | Assume all input is malicious. Use an "accept known good" input
validation strategy, i.e., use a whitelist of acceptable inputs that
strictly conform to specifications. Reject any input that does not
strictly conform to specifications, or transform it into something that
does.When performing input validation, consider all potentially relevant
properties, including length, type of input, the full range of
acceptable values, missing or extra inputs, syntax, consistency across
related fields, and conformance to business rules. As an example of
business rule logic, "boat" may be syntactically valid because it only
contains alphanumeric characters, but it is not valid if the input is
only expected to contain colors such as "red" or "blue."Do not rely exclusively on looking for malicious or malformed inputs
(i.e., do not rely on a blacklist). A blacklist is likely to miss at
least one undesirable input, especially if the code's environment
changes. This can give attackers enough room to bypass the intended
validation. However, blacklists can be useful for detecting potential
attacks or determining which inputs are so malformed that they should be
rejected outright. | | |
Implementation | Output Encoding | 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 whitelist
(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). | | |
Implementation | Input Validation | 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 whitelist validation
schemes by introducing dangerous inputs after they have been
checked. | | |
Relationships
Related CWE | Type | View | Chain |
---|
CWE-154 ChildOf CWE-896 | Category | CWE-888 | |
Demonstrative ExamplesNone
Observed Examples
- 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.
For more examples, refer to CVE relations in the bottom box.
White Box Definitions None
Black Box Definitions None
Taxynomy Mappings
Taxynomy | Id | Name | Fit |
---|
PLOVER | | Variable Name Delimiter | |
References:None