SEC31-J. Never grant AllPermission to untrusted code

The java.security.AllPermission class grants all possible permissions to the caller. This facility was included for routine testing purposes to make it less cumbersome to deal with a multitude of permissions or for use when the code is completely trusted. It should never be applied to untrusted code.

Noncompliant Code Example

This noncompliant example grants AllPermission to a library (klib). The permission itself is specified in the security policy file used by the security manager. Alternatively, a permission object can be obtained in the code by subclassing the Permission class (or any subclass like BasicPermission) in the java.security package.

/* grant the klib library AllPermission */ 
grant codebase "file:${klib.home}/j2ee/home/klib.jar" { 
  permission java.security.AllPermission; 
}; 

Compliant Solution

The policy file can be signed and made to provide more restrictive permissions.

grant codeBase "file:${klib.home}/j2ee/home/klib.jar", signedBy "Admin" {
    permission java.io.FilePermission "/tmp/*", "read";
    permission java.io.SocketPermission "*", "connect";
};

Always assign appropriate permissions to code. This can be achieved by extending any of the permission classes. The solution below shows how to implement restrictive permissions within the code.

//security manager code
perm = new java.io.FilePermission("/tmp/JavaFile","read");
//other code

Exceptions

SEC31-EX1: It may be necessary to grant AllPermission to trusted library code so that callbacks will work.

For example, it is common practice to grant AllPermission to the Java system code:

// Standard extensions get all permissions by default

grant codeBase "file:${{java.ext.dirs}}/*" {
	permission java.security.AllPermission;
};

Risk Assessment

Granting AllPermission to untrusted code means that there is no security at all.

Automated Detection

TODO

Related Vulnerabilities

Search for vulnerabilities resulting from the violation of this rule on the CERT website.

References

[[Gong 03]]
[[API 06]] AllPermission
[[Security 06]] Security Architecture