In Unix file system permissions, the "others" category refers to all users except the owner of the file system resource and the
members of the group assigned to this resource.
Granting permissions to this category can lead to unintended access to files or directories that could allow attackers to obtain sensitive
information, disrupt services or elevate privileges.
Ask Yourself Whether
- The application is designed to be run on a multi-user environment.
- Corresponding files and directories may contain confidential information.
There is a risk if you answered yes to any of those questions.
Recommended Secure Coding Practices
The most restrictive possible permissions should be assigned to files and directories.
Sensitive Code Example
public void setPermissions(String filePath) {
Set<PosixFilePermission> perms = new HashSet<PosixFilePermission>();
// user permission
perms.add(PosixFilePermission.OWNER_READ);
perms.add(PosixFilePermission.OWNER_WRITE);
perms.add(PosixFilePermission.OWNER_EXECUTE);
// group permissions
perms.add(PosixFilePermission.GROUP_READ);
perms.add(PosixFilePermission.GROUP_EXECUTE);
// others permissions
perms.add(PosixFilePermission.OTHERS_READ); // Sensitive
perms.add(PosixFilePermission.OTHERS_WRITE); // Sensitive
perms.add(PosixFilePermission.OTHERS_EXECUTE); // Sensitive
Files.setPosixFilePermissions(Paths.get(filePath), perms);
}
public void setPermissionsUsingRuntimeExec(String filePath) {
Runtime.getRuntime().exec("chmod 777 file.json"); // Sensitive
}
public void setOthersPermissionsHardCoded(String filePath ) {
Files.setPosixFilePermissions(Paths.get(filePath), PosixFilePermissions.fromString("rwxrwxrwx")); // Sensitive
}
Compliant Solution
On operating systems that implement POSIX standard. This will throw a UnsupportedOperationException on Windows.
public void setPermissionsSafe(String filePath) throws IOException {
Set<PosixFilePermission> perms = new HashSet<PosixFilePermission>();
// user permission
perms.add(PosixFilePermission.OWNER_READ);
perms.add(PosixFilePermission.OWNER_WRITE);
perms.add(PosixFilePermission.OWNER_EXECUTE);
// group permissions
perms.add(PosixFilePermission.GROUP_READ);
perms.add(PosixFilePermission.GROUP_EXECUTE);
// others permissions removed
perms.remove(PosixFilePermission.OTHERS_READ); // Compliant
perms.remove(PosixFilePermission.OTHERS_WRITE); // Compliant
perms.remove(PosixFilePermission.OTHERS_EXECUTE); // Compliant
Files.setPosixFilePermissions(Paths.get(filePath), perms);
}
See
