The anonymous user account is denied write access by default. In order to successfully exploit this vulnerability with write access, the anonymous user account would need to have write access ACLs set within the IIS folder structure. However, by default, the anonymous user account only has read access ACLs set. On IIS 6.0, there is an explicit deny ACE for the default anonymous user account. Unless overridden by the administrator, this deny ACE will be inherited by all children under the default Web site root.