Security Insights

Twitter ReTweet Spam (XSS)

Twitter ReTweet Spam (XSS)

This morning before I even logged into my system, I was receiving inquiries about the Twitter Spam going around. The source looks like:

And appears in Twitter as:

For those unfamiliar with, it is Twitter's link service, which provides URL shortening as well as checks to ensure that the link doesn't go to a known malicious site (see About Twitter's Link Service for more info). You can see from the source of the tweet, that it is leveraging a cross-site scripting (XSS) vulnerability so that the scripting code following the "@" character is executed within the victim's browser, and just by mousing over the tweet you are retweeting it. The tweet name / retweet value varies. ( has been seen in addition to the domain).

Doing a Twitter search for "Onmouseover" provides a laundry list of URLs and "victims" of this spam. The results of the spam campaign are tweet spam (annoyance) and a likely strain on Twitter services from the increase in retweets. After doing a Twitter search, after a few minutes, the search results showed over 30K more tweets since my initial search - this illustrates how rapidly spreading the XSS retweet spam is being spread.

Digging a bit deeper into this reveals that it was an Australian teenager going by the handle zzap that discovered the XSS vulnerability whereby arbitrary script following the "@" character is executed (ref. NetCraft). Cross-site request forgery and cookie stealing attacks have been demonstrated leveraging the XSS vulnerability as well. Currently there are a number of Twitter worms leveraging this vulnerability (ref. F-Secure).

Some security precautions for users to consider:

  • Avoid accessing your Twitter account from a browser, consider using a Twitter client
  • If accessing your account via browser turn off JavaScript or use NoScript

Update from Twitter:

Get the latest Zscaler blog updates in your inbox

Subscription confirmed. More of the latest from Zscaler, coming your way soon!

By submitting the form, you are agreeing to our privacy policy.