Much of the confusion surrounding penetration testing stems from the fact it is a relatively recent and rapidly evolving field. Additionally, many organisations will have their own internal terminology (one man’s penetration test is another’s vulnerability audit or technical risk assessment).

At its simplest, a penetration-test (actually, we prefer the term security assessment) is the process of actively evaluating your information security measures. Note the emphasis on ‘active’ assessment; the information systems will be tested to find any security issues, as opposed to a solely theoretical or paper-based audit.

The results of the assessment will then be documented in a report, which should be presented at a debriefing session, where questions can be answered and corrective strategies can be freely discussed.

From a business perspective, penetration testing helps safeguard your organisation against failure, through:

• Preventing financial loss through fraud (hackers, extortionists and disgruntled employees) or through lost revenue due to unreliable business systems and processes.
• Proving due diligence and compliance to your industry regulators, customers and shareholders. Non-compliance can result in your organisation losing business, receiving heavy fines, gathering bad PR or ultimately failing. At a personal level it can also mean the loss of your job, prosecution and sometimes even imprisonment.
• Protecting your brand by avoiding loss of consumer confidence and business reputation.

From an operational perspective, penetration testing helps shape information security strategy through:

• Identifying vulnerabilities and quantifying their impact and likelihood so that they can be managed proactively; budget can be allocated and corrective measures implemented.

All parts of the way that your organisation captures, stores and processes information can be assessed; the systems that the information is stored in, the transmission channels that transport it, and the processes and personnel that manage it. Examples of areas that are commonly tested are:

• Off-the-shelf products (operating systems, applications, databases, hardware, switches, appliances, networking equipment etc.)
• Bespoke development (dynamic web sites, in-house applications etc.)
• Telephony (war-dialling, remote access etc.)
• Wireless (WIFI, Bluetooth, IR, GSM, RFID etc.)
• Personnel (screening process, social engineering etc.)
• Physical (access controls, dumpster diving etc.)

Ideally, your organisation should have already conducted a risk assessment, so will be aware of the main threats (such as communications failure, e-commerce failure, loss of confidential information etc.), and can now use a security assessment to identify any vulnerabilities that are related to these threats. If you haven’t conducted a risk assessment, then it is common to start with the areas of greatest exposure, such as the public facing systems; web sites, email gateways, remote access platforms etc.

Sometimes the ‘what’ of the process may be dictated by the standards that your organisation is required to comply with. For example, a credit-card handling standard (like PCI) may require that all the components that store or process card-holder data are assessed.

While a great deal of technical effort is applied during the testing and analysis, the real value of a penetration test is in the report and debriefing that you receive at the end. If they are not clear and easy to understand, then the whole exercise is of little worth.

Ideally the report and debriefing should be broken into sections that are specifically targeted at their intended audience. Executives need the business risks and possible solutions clearly described in layman's terms, managers need a broad overview of the situation without getting lost in detail, and technical personnel need a list of vulnerabilities to address, with recommended solutions.

Defining the scope

The scope should be clearly defined, not only in the context of the components to be (or not to be) assessed and the constraints under which testing should be conducted, but also the business and technical objectives. For example penetration testing may be focussed purely on a single application on a single server, or may be more far reaching; including all hosts attached to a particular network.

Choosing a security partner

Another critical step to ensure that your project is a success is in choosing which supplier to use.

As an absolute fundamental when choosing a security partner, first eliminate the supplier who provided the systems that will be tested. To use them will create a conflict of interest (will they really tell you that they deployed the systems insecurely, or quietly ignore some issues).

Detailed below are some questions that you might want to ask your potential security partner:

• Is security assessment their core business?
• How long have they been providing security assessment services?
• Do they offer a range of services that can be tailored to your specific needs?
• Are they vendor independent (do they have NDAs with vendors that prevent them passing information to you)?
• Do they perform their own research, or are they dependent on out-of-date information that is placed in the public domain by others?
• What are their consultant’s credentials?
• How experienced are the proposed testing team (how long have they been testing, and what is their background and age)?
• Do they hold professional certifications, such as PCI, CISSP, CISA, and CHECK?
• Are they recognised contributors within the security industry (white papers, advisories, public speakers etc)?
• Are the CVs available for the team that will be working on your project?
• How would the supplier approach the project?
• Do they have a standardised methodology that meets and exceeds the common ones, such as OSSTMM, CHECK and OWASP?
• Can you get access to a sample report to assess the output (is it something you could give to your executives; do they communicate the business issues in a non-technical manner)?
• What is their policy on confidentiality?
• Do they outsource or use contractors?
• Are references available from satisfied customers in the same industry sector?
• Is there a legal agreement that will protect you from negligence on behalf of the supplier?
• Does the supplier maintain sufficient insurance cover to protect your organisation?

There are a number of good standards and guidelines in relation to information security in general, for penetration tests in particular, and for the storage of certain types of data. Any provider chosen should at least have a working knowledge of these standards and would ideally be exceeding their recommendations.

Notable organisations and standards include:

PCI

The Payment Card Industry (PCI) Data Security Requirements were established in December 2004, and apply to all Members, merchants, and service providers that store, process or transmit cardholder data. As well as a requirement to comply with this standard, there is a requirement to independently prove verification.

ISACA

ISACA was established in 1967 and has become a pace-setting global organization for information governance, control, security and audit professionals. Its IS Auditing and IS Control standards are followed by practitioners worldwide and its research pinpoints professional issues challenging its constituents. CISA, the Certified Information Systems Auditor is ISACA's cornerstone certification. Since 1978, the CISA exam has measured excellence in the area of IS auditing, control and security and has grown to be globally recognized and adopted worldwide as a symbol of achievement.

CHECK

The CESG IT Health Check scheme was instigated to ensure that sensitive government networks and those constituting the GSI (Government Secure Intranet) and CNI (Critical National Infrastructure) were secured and tested to a consistent high level. The methodology aims to identify known vulnerabilities in IT systems and networks which may compromise the confidentiality, integrity or availability of information held on that IT system. In the absence of other standards, CHECK has become the de-facto standard for penetration testing in the UK. This is mainly on account of its rigorous certification process. Whilst good it only concentrates on infrastructure testing and not application. However, open source methodologies such as the following are providing viable and comprehensive alternatives, without UK Government association. It must also be noted that CHECK consultants are only required when the assessment is for HMG or related parties, and meets the requirements above. If you want a CHECK test you will need to surrender your penetration testing results to CESG.

OSSTMM

The aim of The Open Source Security Testing Methodology Manual (OSSTMM) is to set forth a standard for Internet security testing. It is intended to form a comprehensive baseline for testing that, if followed, ensures a thorough and comprehensive penetration test has been undertaken. This should enable a client to be certain of the level of technical assessment independently of other organisation concerns, such as the corporate profile of the penetration-testing provider.

OWASP

The Open Web Application Security Project (OWASP) is an Open Source community project developing software tools and knowledge based documentation that helps people secure web applications and web services. It is an open source reference point for system architects, developers, vendors, consumers and security professionals involved in designing, developing, deploying and testing the security of web applications and Web Services.

The key areas of relevance are the forthcoming Guide to Testing Security of Web Applications and Web Services and the testing tools under the development projects. The Guide to Building Secure Web Applications not only covers design principals, but also is a useful document for setting out criteria by which to assess vendors and test systems.