Anand Chitipothu

Understanding a phishing attack

25 February 2013 – Bangalore

I opened my mailbox today and found a lot of messages from friends saying that they got a twitter DM (Direct Message) from me, with a phishing link. I opened twitter and looked at sent messages and found a lot of them but none of them were sent by me. I was sure that my twitter accont was compromised.

Understanding the phishing attack

One of the tinyurl used in one of the DMs was http://bit.ly/YQPCXA. I’ve wanted to find what it is doing.

$ curl -I  http://bit.ly/YQPCXA 
HTTP/1.1 301 Moved
Server: nginx
Date: Mon, 25 Feb 2013 02:30:25 GMT
Content-Type: text/html; charset=utf-8
Connection: keep-alive
Set-Cookie: _bit=512accc1-00036-074ec-3d1cf10a;domain=.bit.ly;expires=Sat Aug 24 02:30:25 2013;path=/; HttpOnly
Cache-control: private; max-age=90
Location: http://surl.dk/bvi?fpma
MIME-Version: 1.0
Content-Length: 115

That is a redirect to http://surl.dk/bvi?fpma. Followed it again.

$ curl -I http://surl.dk/bvi?fpma
HTTP/1.1 302 Moved Temporarily
Date: Mon, 25 Feb 2013 02:30:31 GMT
Server: Apache mod_fcgid/2.3.6
X-Powered-By: PHP/5.3.18
Location: http://trvitter.com/r3
Content-Type: text/html

Still another redirect. followed it too.

$ curl -I http://trvitter.com/r3
HTTP/1.1 301 Moved Permanently
Date: Sun, 24 Feb 2013 20:24:39 GMT
Server: Apache/2.2.15 (CentOS)
Location: http://trvitter.com/r3/
Connection: close
Content-Type: text/html; charset=iso-8859-1

trvitter.com? This looks like a fishing attack. Notice that the domain name looks similar to `twitter.com’.

$ curl -i http://trvitter.com/r3/
HTTP/1.1 200 OK
Date: Sun, 24 Feb 2013 20:26:22 GMT
Server: Apache/2.2.15 (CentOS)
Last-Modified: Sun, 24 Feb 2013 20:26:22 GMT
ETag: W/"ffcd2-4d-4d68239c2c180"
Accept-Ranges: bytes
Content-Length: 77
Connection: close
Content-Type: text/html; charset=UTF-8

<meta http-equiv="refresh" content="0; URL=/g/verify/?&account_secure_login">

Another redirect, this time using a meta tag. Followed that too.

$ curl -i 'http://trvitter.com/g/verify/?&account_secure_login'
...
<!DOCTYPE html>
<html>
  <head>
    ...
    <title>Sign in to Twitter</title>
    ...

Got it! This is a fake twitter login. Looks like the following when opened in a browser.

Fake twitter page

My account would have been compromized after I have clicked one of such phishing links and gave my twitter credentials to a malicious cracker.

How to secure Twitter account after phishing attack

Step 1: Change your password.

Use the advice of xkcd to pick a strong password.

Step 2: Delete all messages sent from your account.

This’ll prevent people from compromising their accounts by clicking the phishing link.

The twitter website doesn’t allow a way to delete multiple DMs at once. I found that www.dmcleaner.com is very useful for this task. You’ll have authorize it via Twitter to use it.

Step 3: Revoke access to all unwanted apps that are authorized by you.

You can find them on Apps tab on Twitter settings page.

See the Twitter Help Center article “My Account Has Been Compromised” for more tips about securing Twitter account.

After you secure your account, make sure you report the phishing link(s) to Google. Google Chrome and Firefox uses that database to warn users when they try to visit those web pages.

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