Knowledgebase: General Questions
What does the abbreviation WAF mean?
Posted by - NA -, Last modified by on 22 January 2008 04:19 PM
A Web Application Firewall is a content filter working at the application layer of the OSI model (layer 7). The WAF weeds out malicious activities from legitimate user requests flowing into web applications.
The requests may be formatted as simple HTTP GET / POST requests coming in from web browsers such as Internet Explorer and Mozilla Firefox, e.g web form submissions.
Web traffic being filtered by the WAF also includes structured request transmissions in the form of XML, e.g. SOAP messages as in the case of Web Services. The receiving applications are usually written in web-oriented programming languages such as PHP and ASP, and utilize a web server such as Apache and IIS to communicate with end users over the HTTP protocol.
As opposed to network-layer (OSI layer 3) attack filtering mechanisms such as network firewalls and IPS, the WAF acts in the following unique methods:

  • Decoding various content encoding schemes, e.g. URL Encoding
  • Inspecting session-wide data as opposed to deep packet-by-packet inspection
  • The ability to filter requests after they have been SSL decrypted as opposed to inline mechanisms such as IPS lacking the correct secret key to decode SSL traffic.
  • Using pattern-matching techniques as opposed to keyword-matching
  • Blocking 0-day and polymorphic attacks using common pattern scrutiny
  • Inspecting both request body and header parameters
  • Coping with attacks such as SQL injection and Cross-Site Scripting attacks against proprietary code as opposed to common attacks such as OS exploits (buffer overflows for instance) that are constantly patched by the software vendors.
(1297 vote(s))
This article was helpful
This article was not helpful

Comments (0)
Post a new comment
Full Name:
CAPTCHA Verification 
Please enter the text you see in the image into the textbox below. This is required to prevent automated registrations and form submissions.

Help Desk Software by Kayako