CWE-732: Incorrect Permission Assignment for Critical Resource

MITRE CWE weakness

Description

The product specifies permissions for a security-critical resource in a way that allows that resource to be read or modified by unintended actors.

When a resource is given a permission setting that provides access to a wider range of actors than required, it could lead to the exposure of sensitive information, or the modification of that resource by unintended parties. This is especially dangerous when the resource is related to program configuration, execution, or sensitive user data. For example, consider a misconfigured storage account for the cloud that can be read or written by a public or anonymous user.

Common consequences

• Confidentiality: Read Application Data, Read Files or Directories
• Access Control: Gain Privileges or Assume Identity
• Integrity, Other: Modify Application Data, Other

Mitigations

Implementation — When using a critical resource such as a configuration file, check to see if the resource has insecure permissions (such as being modifiable by any regular user) [REF-62], and generate an error or even exit the software if there is a possibility that the resource could have been modified by an unauthorized party.

Architecture and Design — Divide the software into anonymous, normal, privileged, and administrative areas. Reduce the attack surface by carefully defining distinct user groups, privileges, and/or roles. Map these against data, functionality, and the related resources. Then set the permissions accordingly. This will allow you to maintain more fine-grained control over your resources. [REF-207]

Architecture and Design — Run the code in a "jail" or similar sandbox environment that enforces strict boundaries between the process and the operating system. This may effectively restrict which files can be accessed in a particular directory or which commands can be executed by the software. OS-level examples include the Unix chroot jail, AppArmor, and SELinux. In general, managed code may provide some protection. For example, java.io.FilePermission in the Java SecurityManager allows the software to specify restrictions on file operations. This may not be a feasible solution, and it only limits the impact to the operating system; the rest of the application may still be subject to compromise. Be careful to avoid CWE-243 and other weaknesses related to jails.

Implementation — During program startup, explicitly set the default permissions or umask to the most restrictive setting possible. Also set the appropriate permissions during program installation. This will prevent you from inheriting insecure permissions from any user who installs or runs the program.

System Configuration — For all configuration files, executables, and libraries, make sure that they are only readable and writable by the software's administrator.

References

• CWE page: https://cwe.mitre.org/data/definitions/732.html
• CWE list: https://cwe.mitre.org/data/index.html