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New Digg Feature = Friend Spamming: Proof of Concept


Update: Ive added like 200+ friends. This is ridiculous.
- Story Buried at 46 Diggs. Hmmm. Who would have thought? Maybe they wouldn’t be able to handle the #of friend requests if it had hit the front page…
- Here is my Befriended List
- You have to be logged in to Digg for the exploit to work


In what has got to be the stupidest move in the history of community features, Digg has created a URL-powered friend-adder. Basically, all you have to do is visit the url http://digg.com/invitefrom/{username} such as http://digg.com/invitefrom/russvirante and you automatically add them as your friend if you are currently logged in to Digg.

So, why is this royally stupid? Why should the inventor / everyone who thought this was a good idea go home for a long, long, long vacation?

<iframe src="http://digg.com/invitefrom/russvirante" height="1" width="1"></iframe>

The proof? I have inserted this code into my page. In about 5 minutes, go check your friends list and say hello to your newest buddy. And then delete me: at least there is a friend remove tool

The simple solution: Add a captcha to the landing page to verify that the user wants to add you as a friend. Come on guys, its not hard to avoid this type of spam.

New Digg Feature = Friend Spamming: Proof of Concept by No tags for this post.

24 Comments

  1. seerox
    Mar 30, 2007

    Wow. Is this some sort of half implemented feature that got deployed? That is silly…

  2. Stuart
    Mar 30, 2007

    Good lord! I feel violated.

  3. Vic
    Mar 30, 2007

    Yep, stupid move found. Digg has turned to crap over the past few months. They leave their self vulnerable to exploit and then do stuff that hurts the community as a whole.

    Some of the users aren’t the sharpest knives in the drawer, if you know what I mean. I’m seriously thinking of blocking all digg.com traffic to my site.

  4. Daniel Drucker
    Mar 30, 2007

    GAH! When will people learn that GET should not perform an action?

    Time for some civil unREST.

  5. Brock
    Mar 30, 2007

    Here’s a list of everyone who’s befriended him:
    http://digg.com/users/russvirante/friends/befriended

  6. omnidugg
    Mar 30, 2007

    Perhaps you could demonstrate the security implications of this by correlating a couple of digg user-names to the IP addresses of their users. Obviously ask their permission before posting it, but I think it would highlight why its essential Digg fix this ASAP.

  7. Chris Finke
    Mar 30, 2007

    And now this story has been buried. I wonder if that was due to actual buries or a direct action taken by Digg staff.

  8. omnidugg
    Mar 30, 2007

    Actually, thinking about it, your probably getting too many hits right now to make that viable… if a page were getting fewer than, say, a hit a minute, it would be a simple matter to correlate the IP of the page view to the new friend on digg.

  9. omnidugg
    Mar 30, 2007

    Brock,

    I think its safe to assume that at least some of those ppl are real digg friends (whatever your interpretation of a digg friend is) rather than people who visited this page.

  10. Jack
    Mar 30, 2007

    No; the real issue is that GET requests — with data embedded in URIs — shoud never change server state. See sec. 9.1 of rfc 2616 (http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html)

    ” In particular, the convention has been established that the GET and HEAD methods SHOULD NOT have the significance of taking an action other than retrieval. These methods ought to be considered “safe”. This allows user agents to represent other methods, such as POST, PUT and DELETE, in a special way, so that the user is made aware of the fact that a possibly unsafe action is being requested.”

    The clear way this should be done, and has been done since the beginning of the web, is to use a POST request. You should have to press a button to make a change; clicking links should always be safe. the RFC goes on:

    “Naturally, it is not possible to ensure that the server does not generate side-effects as a result of performing a GET request; in fact, some dynamic resources consider that a feature. The important distinction here is that the user did not request the side-effects, so therefore cannot be held accountable for them. ”

    This is exactly the situation you describe and exploit. People retrieving the suspect URI in the process of loading your page make no agreement to change state on digg.com.

    Every Web designer and programmer should know these simple rules, but I see them violated far too often. Consider the “click this link to confirm” links sent out in emails. The good ones will load a page that asks you to make a POST request.

    CAPTCHAs are designed to prevent automated actions. Since the users are already logged in, this is likely not necessary but may still be desierable. Certainly, it doesn’t hurt. The key, though, is the request method.

    Consider what happens when bots spider a site. If you allow state changes from GET requests, you’re leaving yourself open to trash coming in from people and bots who are just visiting.

  11. Brock
    Mar 30, 2007

    Sure, but I didn’t say that it was a list of everyone who’s fallen for the trick :)

  12. omnidugg
    Mar 30, 2007

    Bollocks to Digg. I assume someone has submitted this to reddit, delicious, newsvine etc?

  13. danlucas
    Mar 30, 2007

    Actually, you don’t even to be already logged in. If I keep this page open, open a new tab and then log on to digg it still works.

  14. omnidugg
    Mar 30, 2007

    I was just thinking to myself that they oughtta sack the person responsible for this, but… it appears that Kevin Rose himself announced the feature on his blog.

    http://blog.digg.com/?p=70

    You’d have thought he’d check that anything baring his name wasn’t defective by design…

  15. jassimo
    Mar 30, 2007

    Yeah, this is exactly why I started using Plime.com and Reddit and moved away from Digg. It’s smaller and isn’t subject to the same kind of constant exploits.

    http://www.plime.com/
    http://www.reddit.com/

    I’m really surprised Kevin Rose didn’t realize that would happen.

  16. maht
    Mar 30, 2007

    haha RTFM

    http://www.w3.org/Protocols/rfc2616/rfc2616-sec9.html

    9.1.1 Safe Methods

    Implementors should be aware that the software represents the user in their interactions over the Internet, and should be careful to allow the user to be aware of any actions they might take which may have an unexpected significance to themselves or others.

    In particular, the convention has been established that the GET and HEAD methods SHOULD NOT have the significance of taking an action other than retrieval. These methods ought to be considered “safe”. This allows user agents to represent other methods, such as POST, PUT and DELETE, in a special way, so that the user is made aware of the fact that a possibly unsafe action is being requested.

    Naturally, it is not possible to ensure that the server does not generate side-effects as a result of performing a GET request; in fact, some dynamic resources consider that a feature. The important distinction here is that the user did not request the side-effects, so therefore cannot be held accountable for them.

  17. Banjo
    Mar 30, 2007

    captcha’s are super annoying. A simple solution would be to make sure the refering page was from digg. But the best solution would be to require the request to be a post in order to add the friend.

  18. adfasdf
    Mar 30, 2007

    post doesn’t fix it

  19. Crease
    Mar 30, 2007

    Wow Russ, you’re going to turn into this into a Shoemoney/MyBlogLog type battle. I hope Digg doesn’t ban you from the service like they did for him ;)

  20. Tim Linden
    Mar 30, 2007

    It could also just break frames. Then the person will know someone tried to add them as a friend.

  21. CyberMage
    Mar 31, 2007

    Doesn’t look like it works anymore.

  22. feedMashr
    Mar 31, 2007

    I think digg has caught on to this pseudo security flaw already.

  23. You just need to add a little onload javascript to the iframe to click the button for you now. An interesting idea.

  24. Andrew B.
    May 10, 2007

    Hoping to get some advice here. So yesterday our not-for-profit, advertising free, product free, blog (focused on bizarre animal stories http://www.zooillogix.blogspot.com) found itself banned from Digg. All of our posts were removed from Digg. When my brother or I try to login, we receive the message Sorry – bad IP address. When others try to Digg our posts, they receive the message URL Blocked. This URL has been widely reported by users as being regularly used to spam Digg’s submission process and cannot be submitted at this time. This is news to us. We submit our posts to Digg, but do so only once. Digg has not responded to any of our polite requests for information or explanation. Is there any recourse for us here? We really valued our Digg audience.

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