(probably) Everyone knows that firewalls are a “good thing” to have, but how many people actually know how they work? Firewalls can have many features that I won’t go into here, but the basic way they work is that there’s a set of rules that someone sets up (or is given) and the firewall follows those rules. How it does this makes us remember our TCP/IP and UDP connection details. A connection consists of two port/IP pairs – one for the source and one for the destination. A firewall looks at that information (among others) to determine if that packet is “OK” or not. If the packet is OK – based on the rules it’s been given, the “connection” is[…]
Category: Tutorial Tuesday
Each Tuesday, Security Musings features a topic to help educate our readers about security.
The internet is full of unsavory characters who want to steal your personal information and/or money. This has been widely accepted for quite some time. Recently, some good articles have appeared online regarding what to do if you think you’re being scammed, especially by pop-up ads that look like anti-virus software (http://www.fbi.gov/pressrel/pressrel09/popup121109.htm, http://voices.washingtonpost.com/securityfix/2009/09/what_to_do_when_rogue_anti-vir.html). While these articles focus on what to do if you’re hit with such an attack, I’d like to present a few rules of thumb that I use whenever I see any type of message that looks suspicious, whether it is from a pop-up ad, e-mail or letter that purports to be from my bank, or even an unexpected phone call from someone claiming to be from a[…]
You may have heard about the latest SSL vulnerabilities over the last month, but how do they work and what does it mean to you (or your users)? When I earlier described how SSL works, I glossed over two SSL functions: session resumption and re-negotiation. These two functions allow a client or server to renegotiate an SSL connection if they decide they want to use new keys. Session resumption allows the client to use a previous session ID, and have this happen faster – without renegotiating new keying material. These optional protocols allow a man-in-the-middle (MITM) attack. The MITM gets authentication information from the client headers (through sniffing, DNS spoofing, etc.) and replays those to the server – asking for[…]
Last time in our web app input sanitation series, we looked at unsanitized input as part of an HTML tag or attribute. This entry focuses on sanitizing SQL queries. Case 3: Sanitizing SQL Query Data The basic SQL attack takes advantage of improper sanitation to execute its own queries against a database. This can lead to a database being compromised.
A lot of computer security deals with risk – what are the risks of doing or not doing something? However, risk is not exclusive to computer security, and there are many papers and treatises on how to determine and how to manage risk – you’ll generally find papers on risk in management literature, most often project management. Project managers have to deal with risk all of the time – what if the weather is bad, what if a key employee quits on the project? There has to be a plan in place for these eventualities. The same is true in computer security.
In Part 1 of our web app sanitation series, we looked at unsanitized user-controlled data inserted directly into the HTML response of a web page. This entry focuses on a more specific case: user-controlled data being used within a web app in areas like attributes of HTML tags.