Unchecked Input for Loop Condition

Draft Base

Structure: Simple

Description

The product does not properly check inputs that are used for loop conditions, potentially leading to a denial of service or other consequences because of excessive looping.

Common Consequences 1

Scope: Availability

Impact: DoS: Resource Consumption (CPU)

Detection Methods 1

Automated Static AnalysisHigh

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.)

Potential Mitigations 2

Phase: Implementation

Do not use user-controlled data for loop conditions.

Phase: Implementation

Perform input validation.

Demonstrative Examples 2

The following example demonstrates the weakness.

Code Example:Bad
C
c

ID : DX-91

In the following C/C++ example the method processMessageFromSocket() will get a message from a socket, placed into a buffer, and will parse the contents of the buffer into a structure that contains the message length and the message body. A for loop is used to copy the message body into a local character string which will be passed to another method for processing.

Code Example:

Bad

// get message from socket and store into buffer*

// process message* success = processMessage(message);} return success;}

However, the message length variable (msgLength) from the structure is used as the condition for ending the for loop without validating that msgLength accurately reflects the actual length of the message body (Unchecked Input for Loop Condition). If msgLength indicates a length that is longer than the size of a message body (Improper Handling of Length Parameter Inconsistency), then this can result in a buffer over-read by reading past the end of the buffer (Buffer Over-read).

References 2

The Art of Software Security Assessment

Mark Dowd, John McDonald, and Justin Schuh

Addison Wesley

2006

ID: REF-62

Automated Source Code Security Measure (ASCSM)

Object Management Group (OMG)

01-2016

http://www.omg.org/spec/ASCSM/1.0/

ID: REF-962

Modes of Introduction

Implementation

Related Weaknesses

ChildOf:

Improper Validation of Specified Quantity in Input (CWE-1284)

CanPrecede:

Excessive Iteration (CWE-834)

Taxonomy Mapping

Software Fault Patterns
OMG ASCSM