The program omits a break statement within a switch or similar
construct, causing code associated with multiple conditions to execute. This can
cause problems when the programmer only intended to execute code associated with
one condition.
Extended Description
This can lead to critical code executing in situations where it should
not.
Time of Introduction
Implementation
Applicable Platforms
Languages
C
C++
Java
.NET
PHP
Likelihood of Exploit
Medium
Detection Factors
White Box:
Omission of a break statement might be intentional, in order to
support fallthrough. Automated detection methods might therefore be
erroneous. Semantic understanding of expected program behavior is
required to interpret whether the code is correct.
Black Box:
Since this weakness is associated with a code construct, it would be
indistinguishable from other errors that produce the same
behavior.
Demonstrative Examples
Example 1
(Bad Code)
Java
{
int month = 8;
switch (month) {
case 1: print("January");
case 2: print("February");
case 3: print("March");
case 4: print("April");
case 5: print("May");
case 6: print("June");
case 7: print("July");
case 8: print("August");
case 9: print("September");
case 10: print("October");
case 11: print("November");
case 12: print("December");
}
println(" is a great month");
}
C and C++
{
int month = 8;
switch (month) {
case 1: printf("January");
case 2: printf("February");
case 3: printf("March");
case 4: printf("April");
case 5: printff("May");
case 6: printf("June");
case 7: printf("July");
case 8: printf("August");
case 9: printf("September");
case 10: printf("October");
case 11: printf("November");
case 12: printf("December");
}
printf(" is a great month");
}
Now one might think that if they just tested case 12, it will display
that the respective month "is a great month." However, if one tested
November, one notice that it would display "November December is a great
month."
Potential Mitigations
Phase
Description
Implementation
Omitting a break statement so that one may fall through is often
indistinguishable from an error, and therefore should be avoided. If you
need to use fall-through capabilities, make sure that you have clearly
documented this within the switch statement, and ensure that you have
examined all the logical possibilities.
Implementation
The functionality of omitting a break statement could be clarified
with an if statement. This method is much safer.
Weakness Ordinalities
Ordinality
Description
Primary
(where the
weakness exists independent of other weaknesses)
Description
