Vulnerability Mapping:
ALLOWEDThis CWE ID may be used to map to real-world vulnerabilities Abstraction: BaseBase - a weakness that is still mostly independent of a resource or technology, but with sufficient details to provide specific methods for detection and prevention. Base level weaknesses typically describe issues in terms of 2 or 3 of the following dimensions: behavior, property, technology, language, and resource.
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Description
The product accidentally uses the wrong operator, which changes the logic in security-relevant ways.
Extended Description
These types of errors are generally the result of a typo by the programmer.
Relationships
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Research Concepts" (CWE-1000)
Nature
Type
ID
Name
ChildOf
Class - a weakness that is described in a very abstract fashion, typically independent of any specific language or technology. More specific than a Pillar Weakness, but more general than a Base Weakness. Class level weaknesses typically describe issues in terms of 1 or 2 of the following dimensions: behavior, property, and resource.
Variant - a weakness
that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
Variant - a weakness
that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
Variant - a weakness
that is linked to a certain type of product, typically involving a specific language or technology. More specific than a Base weakness. Variant level weaknesses typically describe issues in terms of 3 to 5 of the following dimensions: behavior, property, technology, language, and resource.
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
Relevant to the view "Software Development" (CWE-699)
Nature
Type
ID
Name
MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.
The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.
Phase
Note
Implementation
Applicable Platforms
This listing shows possible areas for which the given weakness could appear. These may be for specific named Languages, Operating Systems, Architectures, Paradigms, Technologies, or a class of such platforms. The platform is listed along with how frequently the given weakness appears for that instance.
Languages
C (Sometimes Prevalent)
C++ (Sometimes Prevalent)
Perl (Sometimes Prevalent)
Class: Not Language-Specific (Undetermined Prevalence)
Common Consequences
This table specifies different individual consequences associated with the weakness. The Scope identifies the application security area that is violated, while the Impact describes the negative technical impact that arises if an adversary succeeds in exploiting this weakness. The Likelihood provides information about how likely the specific consequence is expected to be seen relative to the other consequences in the list. For example, there may be high likelihood that a weakness will be exploited to achieve a certain impact, but a low likelihood that it will be exploited to achieve a different impact.
Scope
Impact
Likelihood
Other
Technical Impact: Alter Execution Logic
This weakness can cause unintended logic to be executed and other unexpected application behavior.
Likelihood Of Exploit
Low
Demonstrative Examples
Example 1
The following C/C++ and C# examples attempt to validate an int input parameter against the integer value 100.
(bad code)
Example Language: C
int isValid(int value) {
if (value=100) {
printf("Value is valid\n"); return(1);
} printf("Value is not valid\n"); return(0);
}
(bad code)
Example Language: C#
bool isValid(int value) {
if (value=100) {
Console.WriteLine("Value is valid."); return true;
} Console.WriteLine("Value is not valid."); return false;
}
However, the expression to be evaluated in the if statement uses the assignment operator "=" rather than the comparison operator "==". The result of using the assignment operator instead of the comparison operator causes the int variable to be reassigned locally and the expression in the if statement will always evaluate to the value on the right hand side of the expression. This will result in the input value not being properly validated, which can cause unexpected results.
Example 2
The following C/C++ example shows a simple implementation of a stack that includes methods for adding and removing integer values from the stack. The example uses pointers to add and remove integer values to the stack array variable.
(bad code)
Example Language: C
#define SIZE 50 int *tos, *p1, stack[SIZE];
void push(int i) {
p1++; if(p1==(tos+SIZE)) {
// Print stack overflow error message and exit
} *p1 == i;
}
int pop(void) {
if(p1==tos) {
// Print stack underflow error message and exit
} p1--; return *(p1+1);
}
int main(int argc, char *argv[]) {
// initialize tos and p1 to point to the top of stack tos = stack; p1 = stack; // code to add and remove items from stack ... return 0;
}
The push method includes an expression to assign the integer value to the location in the stack pointed to by the pointer variable.
However, this expression uses the comparison operator "==" rather than the assignment operator "=". The result of using the comparison operator instead of the assignment operator causes erroneous values to be entered into the stack and can cause unexpected results.
Example 3
The example code below is taken from the CVA6 processor core of the HACK@DAC'21 buggy OpenPiton SoC. Debug access allows users to access internal hardware registers that are otherwise not exposed for user access or restricted access through access control protocols. Hence, requests to enter debug mode are checked and authorized only if the processor has sufficient privileges. In addition, debug accesses are also locked behind password checkers. Thus, the processor enters debug mode only when the privilege level requirement is met, and the correct debug password is provided.
The following code [REF-1377] illustrates an instance of a vulnerable implementation of debug mode. The core correctly checks if the debug requests have sufficient privileges and enables the debug_mode_d and debug_mode_q signals. It also correctly checks for debug password and enables umode_i signal.
(bad code)
Example Language: Verilog
module csr_regfile #(
...
// check that we actually want to enter debug depending on the privilege level we are currently in
unique case (priv_lvl_o)
However, it grants debug access and changes the privilege level, priv_lvl_o, even when one of the two checks is satisfied and the other is not. Because of this, debug access can be granted by simply requesting with sufficient privileges (i.e., debug_mode_q is enabled) and failing the password check (i.e., umode_i is disabled). This allows an attacker to bypass the debug password checking and gain debug access to the core, compromising the security of the processor.
A fix to this issue is to only change the privilege level of the processor when both checks are satisfied, i.e., the request has enough privileges (i.e., debug_mode_q is enabled) and the password checking is successful (i.e., umode_i is enabled) [REF-1378].
(good code)
Example Language: Verilog
module csr_regfile #(
...
// check that we actually want to enter debug depending on the privilege level we are currently in
unique case (priv_lvl_o)
Chain: data visualization program written in PHP uses the "!=" operator instead of the type-strict "!==" operator (CWE-480) when validating hash values, potentially leading to an incorrect type conversion (CWE-704)
Chain: Python-based HTTP Proxy server uses the wrong boolean operators (CWE-480) causing an incorrect comparison (CWE-697) that identifies an authN failure if all three conditions are met instead of only one, allowing bypass of the proxy authentication (CWE-1390)
Detection Methods
Automated Static Analysis
This weakness can be found easily using static analysis. However in some cases an operator might appear to be incorrect, but is actually correct and reflects unusual logic within the program.
Manual Static Analysis
This weakness can be found easily using static analysis. However in some cases an operator might appear to be incorrect, but is actually correct and reflects unusual logic within the program.
Memberships
This MemberOf Relationships table shows additional CWE Categories and Views that reference this weakness as a member. This information is often useful in understanding where a weakness fits within the context of external information sources.
Nature
Type
ID
Name
MemberOf
Category - a CWE entry that contains a set of other entries that share a common characteristic.
View - a subset of CWE entries that provides a way of examining CWE content. The two main view structures are Slices (flat lists) and Graphs (containing relationships between entries).
(this CWE ID could be used to map to real-world vulnerabilities)
Reason: Acceptable-Use
Rationale:
This CWE entry is at the Base level of abstraction, which is a preferred level of abstraction for mapping to the root causes of vulnerabilities.
Comments:
Carefully read both the name and description to ensure that this mapping is an appropriate fit. Do not try to 'force' a mapping to a lower-level Base/Variant simply to comply with this preferred level of abstraction.
Taxonomy Mappings
Mapped Taxonomy Name
Node ID
Fit
Mapped Node Name
CLASP
Using the wrong operator
CERT C Secure Coding
EXP45-C
CWE More Abstract
Do not perform assignments in selection statements
CERT C Secure Coding
EXP46-C
CWE More Abstract
Do not use a bitwise operator with a Boolean-like operand
[REF-62] Mark Dowd, John McDonald
and Justin Schuh. "The Art of Software Security Assessment". Chapter 6, "Typos", Page 289. 1st Edition. Addison Wesley. 2006.
Description
This table shows the weaknesses and high level categories that are related to this weakness. These relationships are defined as ChildOf, ParentOf, MemberOf and give insight to similar items that may exist at higher and lower levels of abstraction. In addition, relationships such as PeerOf and CanAlsoBe are defined to show similar weaknesses that the user may want to explore.
