Cox Communications employee William Bryant recently pleaded guilty to information technology sabotage, having caused the loss of computer, telecommunications and emergency 911 services for thousands of Cox's business and residential customers throughout Dallas, Las Vegas, New Orleans and Baton Rouge.

Bryant faces a 10-year jail sentence and a US$250,000 fine, but the future is less certain for Cox. Although services were fully restored, the incident's effect on Cox's reputation has yet to be determined.

The Cox story, along with recently publicised incidents at NASA, Accenture, Gap and Medco, serve as a harsh reminder that insiders represent a common and often misunderstood threat. Data theft and sabotage can result in hard costs, compliance-related problems, legal fees, productivity loss and, possibly most costly, loss of reputation.

Insider threats are up 17 percent, according to the latest Computer Security Institute survey (a trend echoed by recent surveys by Deloitte and by CSO magazine). As IT and communication systems grow in complexity, so too do the numbers of employees, contractors and managed service providers required to maintain them. The spike in threats is not surprising given the often unfettered and unmonitored access these insiders have to critical corporate networks.

It should be clear that companies need to monitor insiders as aggressively as they do outsiders. However, policing insiders can prove challenging given the privileged access they require to do their jobs. Here are the five most common methods insiders use to access network resources and simple measures enterprise IT can take to protect against the implied threats.

1. Modems. A lack of central management combined with easy-to-guess static passwords make modems an ideal entry point for insiders with detailed knowledge of a network. Many companies have tried to address this challenge by simply unplugging modems until needed. However, unplugging modems makes it impossible to use them for their intended purpose, namely remotely restoring critical systems in times of emergency or outage.

Given that modems are a necessity, enterprises must extend the same security and identity confirmation measures to modems that they do to other remote-network entry points. Extending corporate two-factor authentication measures to modems or replacing legacy modems with newer, more secure models with embedded multifactor authentication can provide appropriate and cost-effective protection.

2. Open file transfer. Most organisations use open file transfer to patch network infrastructure. Internal technicians and vendors use this poorly secured, unrestricted access to troubleshoot, apply appropriate fixes and correct problems. However, they also can misuse this freedom to change files, remove critical components or disrupt systems, resulting in non-operational systems, website defacements, data theft and other damaging situations.

A disgruntled or former employee could have the knowledge and motivation to commit such acts. However, more often, an insider threat can be less dramatic but equally troublesome. Even well-intentioned employees can be careless or make inadvertent mistakes. As such, protecting information assets requires you to have control over who can upload and download files, and a clear and easily retrievable record of all changes made to the system and the person who made them.

Traditionally, limiting and monitoring open file transfer required that individual permissions be set on each machine, causing headaches for IT departments. However, new technologies, such as vendor access and control (VAC) systems, can limit access and monitor activities organisation-wide or for specific systems.

3. Open telnet and SSH ports. Companies that use third parties to remotely access and troubleshoot systems should properly secure or close telnet and SSH ports. Without these protections in place, all a remote technician needs is a single internal IP address to get anywhere on your network without your knowledge.

It is dangerous to assume that remote technicians have limited knowledge of your IP addressing schemes, as it is possible the same technician has worked on site at your facility. Also, infrastructure equipment often shares one easily guessed password, making it simple for an insider to access unauthorised equipment.

As a standard practice, it is recommended that companies restrict third-party access via telnet or SSH to systems beyond the typical scope of their services, unless the session is recorded or actively shadowed by a member of your team. Alternatively, many organisations use intermediary systems to create a proxy for these sessions, adding the needed level of control and tracking.

4. Server console ports. Technicians frequently connect to serial console ports, very often on routers and Linux/Unix servers. To provide scalable access, companies will typically connect to serial console ports using terminal servers. However, terminal servers, by default, offer minimal security. By gaining access to a single terminal server, an insider can access and potentially disable thousands of systems. As such, it is recommended that companies regularly review terminal server security capabilities and place security devices outside the console ports of systems hosting sensitive data (for example, financial records, customer data and human resources information).

5. Unmonitored extranet traffic. Extranets provide a convenience for companies, allowing them to open their networks to vendors, customers and partners to support real-time collaboration. Extranets (for example, IPSec, SSL, remote desktop) work reasonably well when the number of systems to be shared with outsiders is small and the authorisation level on those systems can be tightly controlled.

However, typical extranets, where access to many systems is required or where high-level authorisation must be granted, can be problematic. Often, too much access is granted inadvertently, and activities cannot be closely monitored and controlled. As opposed to typical extranets, vendor access and control systems offer the extra layer of control needed to prevent sabotage and data theft.

While many third-party providers are trustworthy, it is risky to make that assumption. Regardless of whether employees and/or third-party providers access your network, human motivations remain the same. With any insider, there is the prospect of misuse, possibility of mistakes, and opportunity for theft. Increased awareness combined with a few protective measures can reduce the risk.

Whitney is CTO and co-founder of Ion Networks. He can be reached at [email protected]