Common Weakness Enumeration

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CWE-428: Unquoted Search Path or Element

Weakness ID: 428
Abstraction: Base
Structure: Simple
Status: Draft
Presentation Filter:
+ Description
The product uses a search path that contains an unquoted element, in which the element contains whitespace or other separators. This can cause the product to access resources in a parent path.
+ Extended Description
If a malicious individual has access to the file system, it is possible to elevate privileges by inserting such a file as "C:\Program.exe" to be run by a privileged program making use of WinExec.
+ Relationships

The table(s) below 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)
ChildOfClassClass668Exposure of Resource to Wrong Sphere
+ Relevant to the view "Development Concepts" (CWE-699)
MemberOfCategoryCategory417Channel and Path Errors
+ Modes Of Introduction

The different Modes of Introduction provide information about how and when this weakness may be introduced. The Phase identifies a point in the software life cycle at which introduction may occur, while the Note provides a typical scenario related to introduction during the given phase.

+ Applicable Platforms
The listings below show 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.


Class: Language-Independent (Undetermined Prevalence)

Operating Systems

Windows NT (Sometimes Prevalent)

Windows NT (Sometimes Prevalent)

Windows NT (Sometimes Prevalent)

macOS (Rarely Prevalent)

+ Common Consequences

The table below 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.


Technical Impact: Execute Unauthorized Code or Commands

+ Demonstrative Examples

Example 1

The following example demonstrates the weakness.

(bad code)
Example Language:
UINT errCode = WinExec( "C:\\Program Files\\Foo\\Bar", SW_SHOW );
+ Observed Examples
Small handful of others. Program doesn't quote the "C:\Program Files\" path when calling a program to be executed - or any other path with a directory or file whose name contains a space - so attacker can put a malicious program.exe into C:.
CreateProcess() and CreateProcessAsUser() can be misused by applications to allow "program.exe" style attacks in C:
Applies to "Common Files" folder, with a malicious common.exe, instead of "Program Files"/program.exe.
+ Potential Mitigations

Phase: Implementation

Properly quote the full search path before executing a program on the system.

Phase: Implementation

Strategy: Input Validation

Assume all input is malicious. Use an "accept known good" input validation strategy, i.e., use a whitelist of acceptable inputs that strictly conform to specifications. Reject any input that does not strictly conform to specifications, or transform it into something that does.

When performing input validation, consider all potentially relevant properties, including length, type of input, the full range of acceptable values, missing or extra inputs, syntax, consistency across related fields, and conformance to business rules. As an example of business rule logic, "boat" may be syntactically valid because it only contains alphanumeric characters, but it is not valid if the input is only expected to contain colors such as "red" or "blue."

Do not rely exclusively on looking for malicious or malformed inputs (i.e., do not rely on a blacklist). A blacklist is likely to miss at least one undesirable input, especially if the code's environment changes. This can give attackers enough room to bypass the intended validation. However, blacklists can be useful for detecting potential attacks or determining which inputs are so malformed that they should be rejected outright.

Phase: Implementation

Strategy: Input Validation

Inputs should be decoded and canonicalized to the application's current internal representation before being validated (CWE-180). Make sure that the application does not decode the same input twice (CWE-174). Such errors could be used to bypass whitelist validation schemes by introducing dangerous inputs after they have been checked.
+ Functional Areas
  • Program Invocation
+ 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.
MemberOfCategoryCategory417Channel and Path Errors
MemberOfCategoryCategory981SFP Secondary Cluster: Path Traversal
+ Notes

Applicable Platform

This weakness could apply to any OS that supports spaces in filenames, especially any OS that make it easy for a user to insert spaces into filenames or folders, such as Windows. While spaces are technically supported in Unix, the practice is generally avoided. .


This weakness primarily involves the lack of quoting, which is not explicitly stated as a part of CWE-116. CWE-116 also describes output in light of structured messages, but the generation of a filename or search path (as in this weakness) might not be considered a structured message.

An additional complication is the relationship to control spheres. Unlike untrusted search path (CWE-426), which inherently involves control over the definition of a control sphere, this entry concerns a fixed control sphere in which some part of the sphere may be under attacker control. This is not a clean fit under CWE-668 or CWE-610, which suggests that the control sphere model needs enhancement or clarification.

Research Gap

Under-studied, probably under-reported.
+ Taxonomy Mappings
Mapped Taxonomy NameNode IDFitMapped Node Name
PLOVERUnquoted Search Path or Element
+ References
[REF-62] Mark Dowd, John McDonald and Justin Schuh. "The Art of Software Security Assessment". Chapter 11, "Process Loading", Page 654. 1st Edition. Addison Wesley. 2006.
+ Content History
Submission DateSubmitterOrganization
Modification DateModifierOrganization
2008-07-01Eric DalciCigital
updated Potential_Mitigations, Time_of_Introduction
2008-09-08CWE Content TeamMITRE
updated Relationships, Other_Notes, Taxonomy_Mappings
2009-07-27CWE Content TeamMITRE
updated Applicable_Platforms, Description, Maintenance_Notes, Other_Notes, Potential_Mitigations, Relationships
2010-06-21CWE Content TeamMITRE
updated Other_Notes
2011-03-29CWE Content TeamMITRE
updated Potential_Mitigations
2011-06-01CWE Content TeamMITRE
updated Common_Consequences
2012-05-11CWE Content TeamMITRE
updated References, Relationships
2012-10-30CWE Content TeamMITRE
updated Potential_Mitigations
2014-07-30CWE Content TeamMITRE
updated Relationships
2015-12-07CWE Content TeamMITRE
updated Relationships
2017-11-08CWE Content TeamMITRE
updated Applicable_Platforms, Demonstrative_Examples

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Page Last Updated: January 18, 2018