145
Relevant to the view "Software Development" (CWE-699)
Nature Type ID Name Page
MemberOf 137 Data Neutralization Issues 2311
Weakness Ordinalities
Primary :
Applicable Platforms
Language : Not Language-Specific (Prevalence = Undetermined)
Language : PHP (Prevalence = Often)
Common Consequences
Scope Impact Likelihood
Confidentiality
Integrity
Availability
Other
Execute Unauthorized Code or Commands
Alter Execution Logic
Read Application Data
Modify Application Data
An attacker could include arguments that allow unintended
commands or code to be executed, allow sensitive data
to be read or modified or could cause other unintended
behavior.
Detection Methods
Automated Static Analysis
Automated static analysis, commonly referred to as Static Application Security Testing (SAST),
can find some instances of this weakness by analyzing source code (or binary/compiled code)
without having to execute it. Typically, this is done by building a model of data flow and control
flow, then searching for potentially-vulnerable patterns that connect "sources" (origins of input)
with "sinks" (destinations where the data interacts with external components, a lower layer such
as the OS, etc.)
Effectiveness = High
Potential Mitigations
Phase: Implementation
Strategy = Parameterization
Where possible, avoid building a single string that contains the command and its arguments.
Some languages or frameworks have functions that support specifying independent arguments,
e.g. as an array, which is used to automatically perform the appropriate quoting or escaping
while building the command. For example, in PHP, escapeshellarg() can be used to escape a
single argument to system(), or exec() can be called with an array of arguments. In C, code can
often be refactored from using system() - which accepts a single string - to using exec(), which
requires separate function arguments for each parameter.
Effectiveness = High
CWE Version 4.14
CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
CWE-88: Improper Neutralization of Argument
Delimiters in a Command ('Argument Injection') 196
Phase: Architecture and Design
Strategy = Input Validation
Understand all the potential areas where untrusted inputs can enter your product: parameters
or arguments, cookies, anything read from the network, environment variables, request headers
as well as content, URL components, e-mail, files, databases, and any external systems that
provide data to the application. Perform input validation at well-defined interfaces.
Phase: Implementation
Strategy = Input Validation
Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use
a list 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. This 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, denylists can be useful for detecting potential attacks or determining which
inputs are so malformed that they should be rejected outright.
Phase: Implementation
Directly convert your input type into the expected data type, such as using a conversion function
that translates a string into a number. After converting to the expected data type, ensure that the
input's values fall within the expected range of allowable values and that multi-field consistencies
are maintained.
Phase: Implementation
Inputs should be decoded and canonicalized to the application's current internal representation
before being validated (CWE-180, CWE-181). Make sure that your application does not
inadvertently decode the same input twice (CWE-174). Such errors could be used to bypass
allowlist schemes by introducing dangerous inputs after they have been checked. Use
libraries such as the OWASP ESAPI Canonicalization control. Consider performing repeated
canonicalization until your input does not change any more. This will avoid double-decoding and
similar scenarios, but it might inadvertently modify inputs that are allowed to contain properlyencoded
dangerous content.
Phase: 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.
Phase: Implementation
When your application combines data from multiple sources, perform the validation after the
sources have been combined. The individual data elements may pass the validation step but
violate the intended restrictions after they have been combined.
Phase: Testing
Use automated static analysis tools that target this type of weakness. Many modern techniques
use data flow analysis to minimize the number of false positives. This is not a perfect solution,
since 100% accuracy and coverage are not feasible.
Phase: Testing
CWE Version 4.14
CWE-88: Improper Neutralization of Argument Delimiters in a Command ('Argument Injection')
CWE-88: Improper Neutralization of Argument
Delimiters in a Command ('Argument Injection')