Netcraft has found dozens of fake SSL certificates impersonating banks, ecommerce sites, ISPs and social networks. Some of these certificates may be used to carry out man-in-the-middle attacks against the affected companies and their customers. Successful attacks would allow criminals to decrypt legitimate online banking traffic before re-encrypting it and forwarding it to the bank. As the certificates are not signed by trusted certificate authorities, none will be regarded as valid by mainstream web browser software; however, an increasing amount of online banking traffic now originates from apps and other non-browser software which may fail to adequately check the validity of SSL certificates.