1646
Relevant to the view "Software Development" (CWE-699)
Nature Type ID Name Page
MemberOf 1215 Data Validation Issues 2478
Applicable Platforms
Language : Not Language-Specific (Prevalence = Often)
Common Consequences
Scope Impact Likelihood
Other Varies by Context
Potential Mitigations
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.
Effectiveness = High
Demonstrative Examples
Example 1:
The following example retrieves the sizes of messages for a pop3 mail server. The message sizes
are retrieved from a socket that returns in a buffer the message number and the message size,
the message number (num) and size (size) are extracted from the buffer and the message size is
placed into an array using the message number for the array index.
Example Language: C (Bad)
CWE Version 4.14
CWE-1285: Improper Validation of Specified Index, Position, or Offset in Input
CWE-1285: Improper Validation of Specified Index, Position, or Offset in Input