The Return of the Insider Threat
When NTA started security testing twelve years ago, the main focus was on the insider threat. There were many reports with statistics showing that most security breaches were due to insiders. By contrast there was very little focus on the external threat via Internet and third-party network links. Back then many companies did not even have a firewall.
Now almost everyone understands the need for perimeter security, and best practice in this area has improved hugely compared over the last twelve years. But in many sectors, internal security has not improved anywhere near as much. Now, when we perform external and internal penetration tests, it is common to see a reduced level of threat associated with the perimeter security but a much higher level of threat associated with the internal security measures - something that is jokingly referred to as a "hard shell and soft, chewy centre".
Some common themes for poor internal security are:
- No restriction on outbound Internet connections from internal systems, which allows malware to phone home and makes it difficult to prevent data leakage.
- No restriction on portable storage devices, allowing malware in and data out.
- No separation between different categories of system: any host on the network can access any service on any other host.
- Inadequate or incomplete patching, often on servers and network devices, which give malicious internal users a foothold onto systems they are not authorised to use.
- Poor password policy or account deletion procedures, resulting in accounts that can easily be compromised. An old problem that is still common.
Although the potential risk from external attackers is much greater because of their higher numbers, the internal risk is still significant, and if the level of internal security falls too far, it can become the larger threat.
When designing security measures, it is vital to defend on a broad front and ensure that the security measures in all areas meet the minimum required strength. The "weakest link" nature of security means that concentrating in one particular area at the expense of others is generally a mistake.