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CWE

Write-what-where Condition

Description

Any condition where the attacker has the ability to write an arbitrary value to an arbitrary location, often as the result of a buffer overflow.

Likelihood of Exploit: High

Applicable Platforms
Language: C
Language: C++

Time Of Introduction

Common Consequences

Scope	Technical Impact	Notes
Integrity Confidentiality Availability Access_Control	Modify memory Execute unauthorized code or commands Gain privileges / assume identity DoS: crash / exit / restart Bypass protection mechanism	Clearly, write-what-where conditions can be used to write data to areas of memory outside the scope of a policy. Also, they almost invariably can be used to execute arbitrary code, which is usually outside the scope of a program's implicit security policy. If the attacker can overwrite a pointer's worth of memory (usually 32 or 64 bits), he can redirect a function pointer to his own malicious code. Even when the attacker can only modify a single byte arbitrary code execution can be possible. Sometimes this is because the same problem can be exploited repeatedly to the same effect. Other times it is because the attacker can overwrite security-critical application-specific data -- such as a flag indicating whether the user is an administrator.
Integrity Availability	DoS: crash / exit / restart Modify memory	Many memory accesses can lead to program termination, such as when writing to addresses that are invalid for the current process.
Access_Control Other	Bypass protection mechanism Other	When the consequence is arbitrary code execution, this can often be used to subvert any other security service.

Detection Methods
None

Potential Mitigations

Phase	Strategy	Description	Effectiveness	Notes
		Pre-design: Use a language that provides appropriate memory abstractions.
Architecture and Design		Integrate technologies that try to prevent the consequences of this problem.
Implementation		Take note of mitigations provided for other flaws in this taxonomy that lead to write-what-where conditions.
		Operational: Use OS-level preventative functionality integrated after the fact. Not a complete solution.

Relationships

Related CWE	Type	View	Chain
CWE-123 ChildOf CWE-890	Category	CWE-888

Demonstrative Examples (Details)

White Box Definitions
None

Black Box Definitions
None

Taxynomy Mappings

Taxynomy	Id	Name	Fit
CLASP		Write-what-where condition

References:

Michael Howard David LeBlanc John Viega .24 Deadly Sins of Software Security. McGraw-Hill. Section:'"Sin 5: Buffer Overruns." Page 89'. Published on 2010.