CWE-641

Base Abstraction Level
Pillar — Highest-level weakness category
Class — Abstract, language-independent
Base — Specific enough to detect
Variant — Tied to specific technology
Compound — Requires multiple weaknesses Incomplete MITRE CWE Status
Stable — Fully reviewed and complete
Draft — Under development, may change
Incomplete — Partially defined by MITRE
Deprecated — No longer recommended
Obsolete — Replaced by another CWE Exploit: Low
Improper Restriction of Names for Files and Other Resources

Description

The product constructs the name of a file or other resource using input from an upstream component, but it does not restrict or incorrectly restricts the resulting name.

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 vulnerability internal 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.

Consequences

Integrity, Confidentiality, Availability — Execute Unauthorized Code or Commands

Execution of arbitrary code in the context of usage of the resources with dangerous names.

Confidentiality, Availability — Read Application Data, DoS: Crash, Exit, or Restart

Crash of the consumer code of these resources resulting in information leakage or denial of service.

Mitigations

Phase: Architecture and Design

Do not allow users to control names of resources used on the server side.

Phase: Architecture and Design

Perform allowlist input validation at entry points and also before consuming the resources. Reject bad file names rather than trying to cleanse them.

Phase: Architecture and Design

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.