Vulnerabilities A vulnerability is an error made in a program, causing unintended behavior of the program in a way that affects security negatively. FIRST defines a vulnerability as: “a bug, flaw, weakness, or exposure of an application, system, device, or service that could lead to a failure of confidentiality, integrity, or availability.”
Vulnerabilities Examples of vulnerabilities: <ul><li>Weak passwords
Exploits An exploit is a specific example of triggering a vulnerability. If the vulnerability is a missile, the exploit is the warhead.
Exploits Examples of exploits: Morris Worm Almost everything at http://www.milw0rm.com/ http://www.example.com/displayfile.php?../../../../etc/passwd
Exploits Easy way to think about it: If typing “ perl –e ‘print “A” x 10000; ” makes it crash, you’ve found a vulnerability If you end up with this, you’ve got a working exploit: bash-3.00# id uid=0(root) gid=0(wheel) groups=0(wheel), 2(kmem), 3(sys), 4(tty), 5(operator), 20(staff), 31(guest), 45(utmp)
The Security Mindset <ul><li>How many security features are there in a grocery store self-check-out?
Finding Balance “Not all "harmless failures" lead to big trouble, but it's surprising how often a clever adversary can pile up a stack of seemingly harmless failures into a dangerous tower of trouble. Harmless failures are bad hygiene. We try to stamp them out when we can.” – Ed Felten, Freedom to Tinker http://preview.tinyurl.com/c6ewzv
Security Architecture The OWASP Secure Coding Principles puts it thus: “ Security architecture starts on the day the business requirements are modeled, and never finish until the last copy of your application is decommissioned. Security is a life-long process, not a one shot accident.” http://www.owasp.org/index.php/Secure_Coding_Principles
Right from the Start <ul>When starting a new application or re-factoring an existing application, you should consider each functional feature, and consider: <li>Is the process surrounding this feature as safe as possible? In other words, is this a flawed process?
If I were evil, how would I abuse this feature?
Is the feature required to be on by default? If so, are there limits or options that could help reduce the risk from this feature?
System roles should be considered when giving out privileges. Administrators of a system generally aren’t also users; while some super-user privileges may be needed to run the system, administrators don’t necessarily need the ability to do anything.
Any problem that is being fixed needs to be treated as an actual problem, and not a symptom. The fix must go through the entire security process the same as new code; a fix isn’t a real fix if it introduces new problems. </li></ul>
Fix Security Issues Correctly It was in the news again days later, when it turned out the fix wasn't a fix.
Don't turn off Valgrind unless you know what you're doing (o hai OpenSSL) </li></ul>
Another OWASP List! Top Ten Most Critical Web Application Security Vulnerabilities 2007 Version
A1 – Cross Site Scripting (XSS) XSS flaws occur whenever an application takes user supplied data and sends it to a web browser without first validating or encoding that content. XSS allows attackers to execute script in the victim’s browser which can hijack user sessions, deface web sites, possibly introduce worms, etc.
A1 – Cross Site Scripting (XSS) <script>window.alert("meow")</script>
A2 – Injection Flaws Injection flaws, particularly SQL injection, are common in web applications. Injection occurs when user-supplied data is sent to an interpreter as part of a command or query. The attacker’s hostile data tricks the interpreter into executing unintended commands or changing data.
A3 - Malicious File Execution Code vulnerable to remote file inclusion (RFI) allows attackers to include hostile code and data, resulting in devastating attacks, such as total server compromise. Malicious file execution attacks affect PHP, XML and any framework which accepts filenames or files from users.
A4 - Insecure Direct Object Reference A direct object reference occurs when a developer exposes a reference to an internal implementation object, such as a file, directory, database record, or key, as a URL or form parameter. Attackers can manipulate those references to access other objects without authorization.
A5 - Cross Site Request Forgery (CSRF) A CSRF attack forces a logged-on victim's browser to send a pre-authenticated request to a vulnerable web application, which then forces the victim's browser to perform a hostile action to the benefit of the attacker. CSRF can be as powerful as the web application that it attacks.
A6 - Information Leakage and Improper Error Handling Applications can unintentionally leak information about their configuration, internal workings, or violate privacy through a variety of application problems. Attackers use this weakness to steal sensitive data, or conduct more serious attacks.
A6 - Information Leakage and Improper Error Handling http://www.owasp.org/index.php/Category:OWASP_WebScarab_Project
A7 - Broken Authentication and Session Management Account credentials and session tokens are often not properly protected. Attackers compromise passwords, keys, or authentication tokens to assume other users' identities.
A8 - Insecure Cryptographic Storage Web applications rarely use cryptographic functions properly to protect data and credentials. Attackers use weakly protected data to conduct identity theft and other crimes, such as credit card fraud.
A9 - Insecure Communications Applications frequently fail to encrypt network traffic when it is necessary to protect sensitive communications.
A10 - Failure to Restrict URL Access Frequently, an application only protects sensitive functionality by preventing the display of links or URLs to unauthorized users. Attackers can use this weakness to access and perform unauthorized operations by accessing those URLs directly.
What next? http://www.owasp.org/index.php/Top_10_2007-Where_to_Go_From_Here
Do some learning <ul><li>http://www.owasp.org/index.php/Category:OWASP_WebGoat_Project
The Hacker Media archive – decades / terabytes worth of Defcon and other talks. </li></ul>
Local AppSec Resources <ul><li>TASK - http://task.to , security user group
OWASP Toronto Chapter - http://www.owasp.org/index.php/Toronto
SECtor Security Conference - http://sector.ca , October 5-7
HackLabTO - http://hacklab.to , free workshops and classes starting this spring </li></ul>
Further Reading And just about everything on http://www.owasp.org Writing Secure Code, 2nd Edition: Michael Howard and David LeBlanc, Microsoft Press (2003) Hacking: The Art Of Exploitation, 2nd Edition: Jon Erickson, No Starch Press (2008)
Thanks <ul><li>My coworker Seth Hardy, whose appsec notes I built on