STRATEGIES AND COUNTERMEASURES
By: Raymond Ankobia

This discusses strategies and countermeasures that will help alleviate threats and vulnerabilities commonly found in web application development.

3.1 Security Management Programs

A security policy drafted and implemented from a holistic viewpoint with full approval of senior executives. There must be security education and awareness campaigns for the development team and administrators to foster a secure development lifecycle. Policies will ensure secure configuration of web servers and back end databases. Key amongst education campaigns is social engineering [8][7] where the attacker deceitfully extracts information directly from authorized people.

3.2 Deployment of Application Firewalls

This is a fairly new concept that offers use of gateways that specifically operate at the application layer. These are stateful, intelligent and content driven programmes/appliances that operate by checking web content. This allows for evaluation of attack signatures and exploits and prevents them from impacting on the targets. They look out and allow legitimate requests of users to reach the backend servers and databases whilst preventing, logging and alerting administrators of malicious activities. Even though these may be able to do a far better job of analysing application content including graphics, they are not a panacea and the battle is far from over. Malicious and encrypted content will still get through firewalls [6].

3.3 Using SSL/TLS (HTTPS) Protocol

SSL/TLS has become the de-facto protocol for deploying secure web applications running on HTTP. It is based on Public Key Technology and X509 certificates, and defined by the Internet Engineering Task Force (IEFT) RFC 2246. This is supported in most web browsers and provides a secure tunnel between the client and the server. The server side almost always authenticates to the client by making available its public key to the client for verification; thereby offering a mechanism to identify rogue servers that impersonate by spoofing IP addresses with wrong DNS entries [8][7].

In most situations, the client side authentication is optional. This is due largely to the overhead of requiring every client to have a public key. This provides confidentiality, integrity and authenticity of transactions between both ends of the traffic. However, it must be emphasised that hackers concentrate on attacking the endpoints'; poor deployment and implementation of applications and databases make easy break-ins.

Poor implementation of a secure protocol does not make it any better. Attention to detailed instructions from these specifications is imperative to get it right.

3.4 Sandboxing and Code Signing

This idea for using sandboxes and signing of code (especially mobile code) is to introduce trust and assurance to the end user as to the origin of the application in question. Sandboxes are restricted and non-privileged operating environments [2][1]. Java Applets use this approach by encapsulating permissions and rights to resources within the programme itself.

This provides a safer environment as the Java Virtual Machine (embedded in most browsers) consults the security manager for any violations or privileged system calls that may compromise the local computer. The author of a code may digitally sign it to give some authenticity and confidence to the end user; allowing that signature to be publicly verified using a certified public directory.

Authenticode is the approach by Microsoft for digitally signing code to provide trust and authenticity of origin. Developers of ActiveX controls/programmes may likewise sign the code to give similar level of trust and authenticity. However, discretion is left entirely to the user to check the authenticity of the digital signatures. [2] Clearly declares, "A digital signature does not, however, provide any guarantee of benevolence or competence". The Sandboxing (by Sun Microsystems) approach offers better assurance since it comes with a built-in security reference monitor that checks the access controls of the objects. These architectures are designed with Public Key Infrastructure (PKI) in mind and require education and awareness programmes on key management and certification authorities.

3.5 Use of Honeypots

These are used to lure potential crackers / hackers. The principle is one of falsifying information and placing it where hackers will eventually find it. The original concept seem to have come from [9] where he managed to bait hackers with falsified information which eventually led to their capture. This allows for the footprints of malicious activities to be logged, monitored and analysed. They help analyse the weak points that may are exposed with subsequent introduction of countermeasures that will seal any weaknesses that may be exploited. Use of this technology does have some legal implications. There is a debate as to whether this is enticement or entrapment and may require legal interpretation before use.

3.6 Using SiteDigger

This is a tool developed by Foundstone Professional Services to help web application developers and administrators test the efficacy of security measures incorporated during design. It works in conjunction with certain API's which will need to be downloaded from Google's website (http://www.google.com/apis/). This tool will help the web application developer or administrator to scan and generate reports of any leakages on a particular website.

3.7 ISO/IEC 17799 (Part I)

This was originally a British code of practice for Information Security Management and was later adopted by ISO as a Standard [5]. This has many facets for compliance and one of them is Systems Development and Maintenance. Part II of this, is for accreditation (currently being vetted by ISO for standardisation).

It engages the certifying party through a rigorous compliance process, which includes the integration of controls and audit trails built into application systems. It encourages stringent checks and controls, Input data validation, message authentication to guard against unauthorised changes, output validation to ensure correct input and processing (the old adage "Garbage In, Garbage out), and the use of cryptographic controls to protect the confidentiality and integrity of information.

It also envisages strict and secure change control procedures and principle of least principle, by making sure that support developers are only given access to areas of their domain.

3.8 Security Audit

Self-Hack Audit [1]. The self-hack audit is an approach that uses methodology used by developers to identify and eliminate security weaknesses in an application before they are discovered and compromised. This will include checking login prompts, brute forcing passwords and setting up limits for login attempts. Penetration Testing. Particular mention is made of The Open Web Application Security Project (OWASP), which is an Open source platform used as a benchmark for testing web application vulnerabilities.

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