Analysis

This honeynet was a high interaction research honeynet deployed by the UK Honeynet Project in a UK ISP data centre. After a few hours of general background network activity, the Redhat Linux 7.3 honeypot was scanned, compromised and an IRC server installed. A number of further compromises occurred, as multiple attackers located the vulnerable system and exploited it for their own purposes, before the honeypot server was used to host a phishing attack targeting a well known US bank. For brevity, this detailed analysis of the uploaded content only covers the activity relevant to the phishing attack.

The first zip file downloaded was bank.zip, via wget from the Romanian FTP server host2.go.ro.

The file was a valid zip archive, and contained the following data:

This was a pre-prepared web site that mimics the official login page for a major US bank. It included a server side PHP script called check.php, intended to harvest any credentials entered by an unsuspecting end user and email them to the phisher. The presence of a Thumbs.db file suggests that the contents was prepared on a MS Windows system. Scrisoare is the Romanian word for letter, suggesting an email or message or Romanian origin.

Analysis of the check.php script (shown below) reveals that this script is a more advanced version of the script used the German phishing incident. Basic checks on the card number received have been added, along with a refinement that uses the credit card number to classify cards into different types and insert the type into the subject line of the email. This suggests basic scripting abilities and not just a simple script kiddie.

The check.php script:

A hard coded IP address of 66.XXX.XXX.XXX was included in the original script, suggesting that the script had already been used on an alternate server (either another compromised host or a test machine local to the attacker). This IP address appears to be a home DSL IP block belonging to a US carrier and no web site is hosted there now. This script also links directly to the real target bank web site, presumably for added realism and to attempt to confuse recipients.

The second file downloaded using FTP was bank1.tgz:

The file was a valid tgz archive, and contained the following data:

The attacker moved the new files into location in the web root and used the pico editor to change popup.html to point to a test server (http://69.24.XX.XX/testing.php). Again, this was possibly a previously compromised host or a system local to the attacker.

Interestingly, because this FTP session was plain text and the attacker helpfully used the directory listing command, we can observe the attacker�s activities and also see what other tools they have stored in their FTP area. Directory listings are often very useful in providing further background detail during incident analysis:

The contents of this FTP server home directory suggests that the phisher is heavily involved in spam and phishing activities, with pre-built content and message delivery tools targeting many well known online brands stored on this server. Based on this captured session, this phishing activity is not likely to be an isolated incident.

The third file downloaded was sendbankNEW.tgz from the Romain FTP server host2.go.ro.

The file was a valid archive and contained the following files:

The purpose of each file is listed in the table below:

The email lure blah.txt was notable for having good grammar and spelling, legalise at the bottom about "Equal Opportunity Lending" and heavy use of files linked directly from the official web site of the targeted bank, all of which help it to appear more realistic. One ironic point to note is that the email even included an exhortation to not provide passwords to fraudulent web sites, or to ever email your password to a third party!

The bank.php mass emailing script to send spam advertising this particular phishing scam is shown below:

Although simple, it is functional and could easily have been used to send many more messages than the 5 test messages sent from the honeynet. The honeynet architecture would have restricted outbound emails, but the honeypot was taken offline for forensic analysis before any bulk spam email could be sent by the attacker.

Timeline

This honeynet was a high interaction research honeynet deployed by the UK Honeynet Project in a UK ISP data centre. After a few hours of general background network activity, the Redhat Linux 7.3 honeypot was scanned, compromised and an IRC server installed. A number of further compromises occurred, as multiple attackers located the vulnerable system and exploited it for their own purposes, before the honeypot server was used to host a phishing attack targeting a well known US bank. For brevity, this detailed timeline only covers the activity relevant to the phishing attack.

Detailed timeline:

18/07/04 - 12:30. First the attacker exploits a buffer overflow in the samba server on the Redhat Linux 7.3 honeypot, as can be seen from the snort alerts shown below:

18/07/04 - 12:30. After a few retries with different offsets, the samba exploit (CAN-2003-0201) succeeds and returns a root prompt to the attacker, as show by the snort alert below:

18/07/04 - 12:30. After gaining root access, the attacker check who they are and who else is logged into the system before attempting to hide their activities by turning off shell history logging. The Sebek keystrokes for this session are shown below:

18/07/04 - 12:31. The attacker then proceeds to downloading what appears to be an image file from a remote web server using the wget command line HTTP client:

18/07/04 - 12:32. The attacker unpacks the image file, which is actually a gziped tar archive, before extracting and running a setup program:

The attackers view of this session can be found here. Analysis showed that the malware installed was the SHV4 root kit, previously the subject of the Honeynet Projects Scan of the Month challenge 29.

From the SHV4 root kit source code, we can determine what the setup command does:

The attacker has installed and configured an encrypted backdoor on the honeypot, bound to TCP port 2277. A large amount of other activity occurs on the system over the next few 12-72 hours, including installation of PsyBNC IRC servers by a Romanian group, installation and usage of the mole and mazz mass scanners (probably the autorooter used to compromise this honeypot), installation and re-installation of other rootkits, password sniffing and various other activities not relevant to the main phishing attack.

23/07/04 - 21:11. The attacker returns from 192.226.XXX.XXX (a Windows 2000 or Windows XP PC in Ontario) via the SSH backdoor listening on TCP port 2277 and checks if the server is still active and who is logged in:

23/07/04 - 21:13. The attacker reconnects, prepares a directory in the Apache web server's document root and then downloads some pre-built web content from a Romanian web server using, again using wget, before checking the honeypot's IP address and PHP configuration:

23/07/04 - 21:15. The attacker attempts to extract the contents of the zip file but finds it is corrupt and deletes it.

23/07/04 - 21:16. The attacker changes tools and gets another file using FTP, again from the same web server in Romania, which does extract successfully this time:

23/07/04 - 21:17. The attacker edits the extracted web content and updates the HTML to point to a testing PHP script on a remote web server:

23/07/04 - 21:22. The attacker checks the network configuration of the honeypot and version of PHP installed:

25/07/04 - 21:42. The attacker opens a second session, checks again if PHP is configured correctly on the honeypot and downloads a tool for sending spam email from the same Romanian web server:

25/07/04 - 22:08. The attacker checks an input list email addresses and runs a PHP script to send spam email:

25/07/04 - 22:10. The attacker edits the content of the spam message, points it a co-located Linux web server running an American student web site, and runs the PHP script to send spam email again:

The attackers initial test at 22:08:52 works as planned, with 5 test messages being successfully sent (although due to the outbound traffic restrictions on the Honeywall, further mass mailing attempts would fail). However, after 10 minutes wait the attacker cleans up and leaves without sending any further messages from this honeypot.

Phishing Incident Victims

In this side note we provide an overview of the source IP addresses of potential victims in the UK phishing attack against a major US bank described in phishing technique one. The data below was collected with the help of the compromised UK honeypot and network packet captures. Over a period of about 4 days we observed 265 inbound HTTP requests to the honeypot, presumably recipients of a spam phishing email who were tricked into accessing the redirected content by clicking on the link provided. All were potential victims of the phishing attack, but none actually submitted personal data and therefore the phishing attack was unsucessful.