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Online Impersonations: No Validation Required
Dr. Neal Krawetz, 2007-04-20

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Refuting Email

In sensitive environments, PGP signatures or similar key-based systems can be used to authenticate the sender. These cryptographic systems validate your identity because only the sender has the right keys. However, few people use PGP for general email communications and it does not authenticate you with new acquaintances.

With free email services, disabling an imposter becomes more difficult. In most cases, you must authenticate yourself before the hosting provider will take action, but not to open the account. For example, anyone can register a Yahoo! Mail account using your name. If Yahoo! Mail has an email account that is impersonating you, then you can fill out their abuse form. This form requires you to describe the incident and identify yourself.

In contrast to Yahoo!, Gmail requires you to print out the imposter's email and mail it to them through the postal service. Gmail offers no method for submitting an online complaint about an imposter.

Although sites such as Yahoo! and Gmail do provide options for refuting and disabling an imposter's account, other public mailing systems are not as responsive. For example, Hushmail allows people to report abuse. However, they will not investigate abuse complaints (other than spam complaints) and refuse to disable any imposter's account without a court order. Since Hushmail does not authenticate during enrollment and does not remove abusive accounts, you should personally verify the sender's identity before responding. Any email from "hushmail.com", "hush.com", "hush.ai", etc., could be an imposter. While Hushmail does use PGP for email authentication, this only validates that the email was sent using Hushmail; it does not validate the person who opened the Hushmail account.

External authentication is one option to mitigate the impact from general email impersonations. Build a reputation around a known email address and maintain a web site that can quickly be used to identify you. If your emails always come from "mydomain.org", then emails from some other domain should be suspect.

Mitigating Mailing Lists

While an imposter's email account can be disabled, the damage from posted messages is usually permanent. While some mailing lists will remove messages from their archives, most will not. And even if the message is removed, many mailing lists are mirrored; an imposter's posting could live indefinitely on hundreds of archive sites. Exposing the imposter by posting to the list or informing the list manager, is usually enough to mitigate any damage.

Unfortunately, some unmoderated forums have a large number of imposters. Contesting an imposter may not be worthwhile; if many people are impersonated, then malicious postings are usually suspect without any feedback from you. In addition, any identification of an imposter could be overlooked in high-volume forums.

Web of Lies

Along with impersonating email addresses, imposters can create fictitious web sites. Yahoo! Mail includes web space at Geocities, Gmail includes Googlepages, and there are thousands of other hosting providers. The inability to authenticate an owner opens the door to impersonations such as phishing; anyone can create a web page that looks like Citibank and anyone can register a domain name similar to "citibank.com". No validation required.

Refuting a fake web site really depends on the type of impersonation and the hosting location. Companies such as Yahoo! and Google are extremely responsive to phishing reports. Due to well-organized efforts by groups such as the Anti-Phishing Working Group, reported phishing sites are usually taken down within hours, and sometimes within minutes. If the hosting site is non-responsive, then network routers can restrict access to these sites until the phishing site is removed.

While web impersonations usually refer to companies, they can also apply to individual people. Unfortunately, if the site is impersonating a person -- and not a company -- then refuting the site becomes more complicated. Yahoo! Geocities links web pages to email accounts. If you can refute the Yahoo! email account, then you can disable the imposter's web page. In general, your ability to refute a fake web page really depends on the hosting provider. Look at their site for a method to report abuse and be prepared to validate that you really are you.

Invading My Space

While email allows you to communicate and web pages provide a narrow view of your world, blog services such as MySpace allow you to create an entire online persona. Visitors can see up-to-date content as well as friendship relationships. Unfortunately, as with email, anyone can create a MySpace profile and impersonate anyone else. Politicians, sports figures, and celebrities are frequently impersonated. Even law enforcement and kidnap victims are not immune. Teachers are another common target for MySpace impersonations.

Refuting a MySpace Profile

Disabling a MySpace imposter is much more difficult than other online services. While Yahoo!, Google, and even Hushmail have well-defined, single-step processes for reporting abuse, MySpace seems intentionally complicated. I have assisted a half-dozen people with the removal of false MySpace profiles, and none have been painless.

MySpace provides a specific FAQ and request form for reporting abuse and impersonation. They want you to (and I'm not kidding) send them a "salute". The salute is "an image of yourself holding a handwritten sign with the word 'MySpace.com' and your Friend ID". If this sounds familiar, it is because it is the same type of embarrassment used at 419eater.com against advanced fee fraud scammers. There are a lot of problems with this type of authentication:

  • Validation. Just because it is a picture of a person does not mean that it is a picture of you. Anyone can use this approach to terminate anyone's MySpace account. MySpace has no method to tell that the picture is of the actual person.
  • Photoshop. Even if the person in the salute is real, there is no way to tell if the sign is real or if it was added to the picture using Photoshop. I know first-hand that photoshopped images are acceptable for terminating imitation MySpace accounts.
  • Submission. Okay, you have your picture of "you" holding a sign. How do you submit it? The MySpace form only allows text, not pictures or attachments. Furthermore, there is no email address for sending the picture. Yes: first they request an unverifiable image, and then they offer no method for submitting it. What they don't tell you is that if you fill out the text form, then they will respond a few days later with an email where you can send the salute.
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Dr. Neal Krawetz operates Hacker Factor Solutions, providing computer security consulting, research and development. He is also the author of "Introduction to Network Security" (Charles River Media) and "Hacking Ubuntu" (Wiley).
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