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Common Weakness Enumeration

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Home > CWE List > CWE-834: Excessive Iteration (4.16)  
ID

CWE-834: Excessive Iteration

Weakness ID: 834
Vulnerability Mapping: DISCOURAGED This CWE ID should not be used to map to real-world vulnerabilities
Abstraction: Class 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.
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+ Description
The product performs an iteration or loop without sufficiently limiting the number of times that the loop is executed.
+ Extended Description
If the iteration can be influenced by an attacker, this weakness could allow attackers to consume excessive resources such as CPU or memory. In many cases, a loop does not need to be infinite in order to cause enough resource consumption to adversely affect the product or its host system; it depends on the amount of resources consumed per iteration.
+ Common Consequences
Section HelpThis 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
Availability

Technical Impact: DoS: Resource Consumption (CPU); DoS: Resource Consumption (Memory); DoS: Amplification; DoS: Crash, Exit, or Restart

Excessive looping will cause unexpected consumption of resources, such as CPU cycles or memory. The product's operation may slow down, or cause a long time to respond. If limited resources such as memory are consumed for each iteration, the loop may eventually cause a crash or program exit due to exhaustion of resources, such as an out-of-memory error.
+ Relationships
Section Help 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 Pillar Pillar - a weakness that is the most abstract type of weakness and represents a theme for all class/base/variant weaknesses related to it. A Pillar is different from a Category as a Pillar is still technically a type of weakness that describes a mistake, while a Category represents a common characteristic used to group related things. 691 Insufficient Control Flow Management
ParentOf Class 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. 674 Uncontrolled Recursion
ParentOf Base Base - 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. 835 Loop with Unreachable Exit Condition ('Infinite Loop')
ParentOf Base Base - 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. 1322 Use of Blocking Code in Single-threaded, Non-blocking Context
CanFollow Base Base - 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. 606 Unchecked Input for Loop Condition
CanFollow Base Base - 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. 1339 Insufficient Precision or Accuracy of a Real Number
Section Help 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 "Weaknesses for Simplified Mapping of Published Vulnerabilities" (CWE-1003)
Nature Type ID Name
MemberOf View 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). 1003 Weaknesses for Simplified Mapping of Published Vulnerabilities
ParentOf Base Base - 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. 835 Loop with Unreachable Exit Condition ('Infinite Loop')
+ Demonstrative Examples

Example 1

In this example a mistake exists in the code where the exit condition contained in flg is never called. This results in the function calling itself over and over again until the stack is exhausted.

(bad code)
Example Language:
void do_something_recursive (int flg)
{
... // Do some real work here, but the value of flg is unmodified
if (flg) { do_something_recursive (flg); } // flg is never modified so it is always TRUE - this call will continue until the stack explodes
}
int flag = 1; // Set to TRUE
do_something_recursive (flag);

Note that the only difference between the Good and Bad examples is that the recursion flag will change value and cause the recursive call to return.

(good code)
Example Language:
void do_something_recursive (int flg)
{
... // Do some real work here
// Modify value of flg on done condition
if (flg) { do_something_recursive (flg); } // returns when flg changes to 0
}
int flag = 1; // Set to TRUE
do_something_recursive (flag);

Example 2

For this example, the method isReorderNeeded is part of a bookstore application that determines if a particular book needs to be reordered based on the current inventory count and the rate at which the book is being sold.

(bad code)
Example Language: Java 
public boolean isReorderNeeded(String bookISBN, int rateSold) {

boolean isReorder = false;

int minimumCount = 10;
int days = 0;

// get inventory count for book
int inventoryCount = inventory.getIventoryCount(bookISBN);

// find number of days until inventory count reaches minimum
while (inventoryCount > minimumCount) {

inventoryCount = inventoryCount - rateSold;
days++;
}

// if number of days within reorder timeframe

// set reorder return boolean to true
if (days > 0 && days < 5) {
isReorder = true;
}

return isReorder;
}

However, the while loop will become an infinite loop if the rateSold input parameter has a value of zero since the inventoryCount will never fall below the minimumCount. In this case the input parameter should be validated to ensure that a value of zero does not cause an infinite loop, as in the following code.

(good code)
Example Language: Java 
public boolean isReorderNeeded(String bookISBN, int rateSold) {
...

// validate rateSold variable
if (rateSold < 1) {
return isReorder;
}

...
}

+ Observed Examples
Reference Description
Chain: off-by-one error (CWE-193) leads to infinite loop (CWE-835) using invalid hex-encoded characters.
Chain: web browser crashes due to infinite loop - "bad looping logic [that relies on] floating point math [CWE-1339] to exit the loop [CWE-835]"
+ Detection Methods

Dynamic Analysis with Manual Results Interpretation

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Fuzz Tester
  • Framework-based Fuzzer
  • Forced Path Execution

Effectiveness: SOAR Partial

Manual Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Cost effective for partial coverage:
  • Focused Manual Spotcheck - Focused manual analysis of source
  • Manual Source Code Review (not inspections)

Effectiveness: SOAR Partial

Automated Static Analysis - Source Code

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Context-configured Source Code Weakness Analyzer

Effectiveness: High

Architecture or Design Review

According to SOAR, the following detection techniques may be useful:

Highly cost effective:
  • Inspection (IEEE 1028 standard) (can apply to requirements, design, source code, etc.)

Effectiveness: High

+ Memberships
Section HelpThis 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 CategoryCategory - a CWE entry that contains a set of other entries that share a common characteristic. 1410 Comprehensive Categorization: Insufficient Control Flow Management
+ Vulnerability Mapping Notes

Usage: DISCOURAGED

(this CWE ID should not be used to map to real-world vulnerabilities)

Reason: Abstraction

Rationale:

This CWE entry is a level-1 Class (i.e., a child of a Pillar). It might have lower-level children that would be more appropriate

Comments:

Examine children of this entry to see if there is a better fit
+ References
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 7, "Looping Constructs", Page 327. 1st Edition. Addison Wesley. 2006.
+ Content History
+ Submissions
Submission Date Submitter Organization
2011-03-22
(CWE 1.12, 2011-03-30)
CWE Content Team MITRE
+ Modifications
Modification Date Modifier Organization
2011-06-01 CWE Content Team MITRE
updated Common_Consequences, Relationships, Taxonomy_Mappings
2012-05-11 CWE Content Team MITRE
updated References, Relationships, Taxonomy_Mappings
2014-07-30 CWE Content Team MITRE
updated Detection_Factors
2017-11-08 CWE Content Team MITRE
updated Relationships
2019-06-20 CWE Content Team MITRE
updated Relationships, Type
2020-02-24 CWE Content Team MITRE
updated Relationships
2020-12-10 CWE Content Team MITRE
updated Relationships
2021-07-20 CWE Content Team MITRE
updated Observed_Examples, Relationships
2023-01-31 CWE Content Team MITRE
updated Common_Consequences, Description, Relationships
2023-04-27 CWE Content Team MITRE
updated Relationships
2023-06-29 CWE Content Team MITRE
updated Mapping_Notes
2023-10-26 CWE Content Team MITRE
updated Observed_Examples
2024-02-29
(CWE 4.14, 2024-02-29)
CWE Content Team MITRE
updated Demonstrative_Examples, Mapping_Notes
Page Last Updated: November 19, 2024