Difference between revisions of "Testing for WS Replay (OWASP-WS-007)"

From OWASP
Jump to: navigation, search
Line 20: Line 20:
 
2. Using the packets captured by ethereal, use TCPReplay to initiate the replay attack by reposting the packet.  It may be necessary to capture many packets over time to determine session id patterns in order to assume a valid session id for the replay attack.  It is also possible to manually post http traffic captured by WebScarab, using WebScarab
 
2. Using the packets captured by ethereal, use TCPReplay to initiate the replay attack by reposting the packet.  It may be necessary to capture many packets over time to determine session id patterns in order to assume a valid session id for the replay attack.  It is also possible to manually post http traffic captured by WebScarab, using WebScarab
  
<nowiki><proof of impersonation></nowiki>
+
[[Image: ReplayWebScarab.jpg]]
  
 
'''Result Expected:'''
 
'''Result Expected:'''

Revision as of 20:09, 19 November 2006

[Up]
OWASP Testing Guide v2 Table of Contents

Contents


Brief Summary

This section describes testing replay vulnerabilities of a web service. The threat for a replay attack is that the attacker can assume the identity of a valid user and commit some nefarious act without detection.

Description of the Issue

A replay attack is a "man-in-the-middle" type of attack where a message is intercepted and replayed by an attacker to impersonate the original sender. For web services, as with other types of HTTP traffic, a sniffer such as Ethereal or Wireshark can capture traffic posted to a web service and using a tool like WebScarab, a tester can resend a packet to the target server. An attacker can attempt to resend the original message or change the message in order to compromise the host server.

Black Box testing and example

Testing for Replay Attack vulnerabilities:

1. Using Wireshark on a network, sniff traffic and filter for web service traffic. Another alternative is to install WebScarab and use it as a proxy to capture http traffic

ReplayWireshark1.jpg

2. Using the packets captured by ethereal, use TCPReplay to initiate the replay attack by reposting the packet. It may be necessary to capture many packets over time to determine session id patterns in order to assume a valid session id for the replay attack. It is also possible to manually post http traffic captured by WebScarab, using WebScarab

File:ReplayWebScarab.jpg

Result Expected:

The tester can assume the identity of the attacker.

Gray Box testing and example

Testing for Replay Attack vulnerabilities

1. Does the web service employ some means of preventing the replay attack? Such as pseudo random Session tokens, Nonces with MAC addresses or Timestamping, for example.

<code example>

2. Can the site employ SSL - this will prevent unauthorized attempts to replay messages?

References

Whitepapers

Tools


OWASP Testing Guide v2

Here is the OWASP Testing Guide v2 Table of Contents