Twitter’s deathless spoofing bug gets the heart-stake again

Twitter says it has plugged its years-old SMS spoofing vulnerability after yet-another disclosure, this time by security consultant Jonathan Rudenberg. Facebook and social payments outfit Venmo have also blocked the vulnerability.

In the case of Twitter, users with SMS-posting enabled weren't forced to use any kind of authentication, although the option to use a PIN for posting was available. If the user didn’t require the PIN, someone who knew their number could post under their identity using an SMS gateway.

The gateway would allow the attacker to send a message to Twitter with the spoofed number, Rudenberg explains in this blog post. In fact, until the vulnerability was fixed, the full set of Twitter commands could be sent under the spoofed ID. The only mitigation, for users in regions that didn’t support PINs, was to disable SMS posts.

Twitter confirmed to Rudenberg that the issue was resolved on December 4. As he also noted, Facebook and Venmo have also plugged the same vulnerability in their networks. All three, he claims, took nearly three months to act, with his first disclosures made to the social networks in mid-August.

What’s surprising about this is that the Twitter spoofing vulnerability has existed since at least 2007, when Twitter first introduced PIN protection for tweets – but didn’t make it a requirement for mobile users.

In 2009, the issue rose up again, shambling like a zombie, with Security Fix reporting that the bug was fixed, while Heise Security said spoofing was still possible, as reported by The Register here. ®