An over-emphasis on tackling new and emerging security threats may be causing companies to overlook older but far more frequently exploited vulnerabilities, says a recent report.

The report, from TrustWave Inc., is based on an analysis of data gathered from over 1900 penetration tests and over 200 data breach investigations conducted on behalf of clients such as American Express, MasterCard, Discover, Visa and several large retailers.

The analysis showed is that major global companies are employing "vulnerability chasers" and searching out the latest vulnerabilities and zero-day threats while overlooking the most common ones, the report said.

As a result, companies continue to be felled by old and supposedly well-understood vulnerabilities rather than by newfangled attack tools and methods.

For instance, the top three ways hackers gained initial access to corporate networks in 2009 were via remote access applications, trusted internal network connections and SQL injection attacks, TrustWave found.

All three attacks points have been well researched and known about for several years. SQL injection vulnerabilities, for instance, have been known about for at least 10 years, but still continue to be widely prevalent in Web-based, database-driven applications, TrustWave said.

The most common vulnerability that TrustWave discovered during its external network penetration tests had to do with the management interfaces for Web application engines such as Websphere, and Cold Fusion. In many cases, the management interfaces were accessible directly from the Internet and had little or no password protection, potentially allowing attackers to deploy their own malicious applications on the Web server.

Similarly unprotected network infrastructure components such as routers, switches and VPN concentrators represented the second most common vulnerability unearthed by TrustWave. The tendency by many companies to host internal applications on the same server that also hosts external content was another common vulnerability, as were misconfigured firewall rules, default or easy-to-guess passwords and DNS cache poisoning.

Meanwhile TrustWave's wireless penetration tests unearthed common weaknesses such as the continued use of WEP encryption, legacy 802.11 networks with minimal to no security controls and wireless clients using public "guest" networks instead of secured private networks.

In almost all of the cases, the most common vulnerabilities unearthed by TrustWave were common well-understood issues that should have been addressed a long time ago said Nicholas Percoco, senior vice president at TrustWave's SpiderLabs research unit.

"There are basically two themes," Percoco said. "Through our study in 2009 we found some very old vulnerabilities present within enterprises, some as old as 20 to 30 years." The second theme is that attackers are targeting these old flaws to break into enterprises, then using increasingly sophisticated tools to harvest data from companies, he said.