CWE-641: Improper Restriction of Names for Files and Other Resources
Improper Restriction of Names for Files and Other Resources
Weakness ID: 641 (Weakness Base)
Status: Incomplete
Description
Description Summary
The application constructs the name of a file or other resource using input from an upstream component, but does not restrict or incorrectly restricts the resulting name.
Extended Description
This may produce resultant weaknesses. For instance, if the names of these resources contain scripting characters, it is possible that a script may get executed in the client's browser if the application ever displays the name of the resource on a dynamically generated web page. Alternately, if the resources are consumed by some application parser, a specially crafted name can exploit some vulnerabilityinternal to the parser, potentially resulting in execution of arbitrary code on the server machine. The problems will vary based on the context of usage of such malformed resource names and whether vulnerabilities are present in or assumptions are made by the targeted technology that would make code execution possible.
Time of Introduction
Architecture and Design
Implementation
Applicable Platforms
Languages
All
Common Consequences
Scope
Effect
Integrity
Confidentiality
Availability
Technical Impact: Execute unauthorized code or
commands
Execution of arbitrary code in the context of usage of the resources
with dangerous names.
Crash of the consumer code of these resources resulting in information
leakage or denial of service.
Likelihood of Exploit
Low
Enabling Factors for Exploitation
Resource names are controllable by the user.
No sufficient validation of resource names at entry points or before
consumption by other processes.
Context where the resources are consumed makes execution of code possible
based on the names of the supplied resources.
Observed Examples
Reference
Description
Format string vulnerability in Dia 0.94 allows
user-assisted attackers to cause a denial of service (crash) and possibly
execute arbitrary code by triggering errors or warnings, as demonstrated via
format string specifiers in a .bmp filename. [CVE-2006-2480 available at:
http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-2480
]
Potential Mitigations
Do not allow users to control names of resources used on the server
side.
Perform white list input validation at entry points and also before
consuming the resources. Reject bad file names rather than trying to
cleanse them.
Make sure that technologies consuming the resources are not vulnerable
(e.g. buffer overflow, format string, etc.) in a way that would allow
code execution if the name of the resource is malformed.