Building a Better Virus Trap

A layered approach to IT security

Not so long ago, viruses were just one of those little annoyances that come along with using a computer, akin to the gnat that orbits your head at the family picnic. But over the past few years, those pesky little pieces of code have steadily moved from simply popping up messages on your screen or deleting your Word files; they now target specific industries and serve as tools for real criminals. Unfortunately, changes happen so quickly that computer security policies struggle to keep pace. Whereas once a mere daily virus scan of a user's PC could clean up the virus problem and a firewall could keep out prowlers, today a much more in-depth, multifaceted, layered approach is the only way to truly protect your valuable assets. Here's a closer look.

The Changing Face of Security

When the first virus was created by Fred Cohen in 1983, the seeds of today's scourge were planted. Cohen's motives were more scientific than malicious, as he created the code to test a theory he had about programs that could self-replicate and spread. And while the means of transmission—a floppy disk—was much easier to control than today's Internet and laptop computers, the method was eerily similar. The virus, which Cohen hid in a graphics program called VD, examined users' permissions and used those permissions for its own purposes. Although the nature of viruses has changed drastically over the 20+ years since Cohen's experiment, permissions continue to represent a major risk to computing environments.

The most significant changes to the virus threat in recent years include:

  • A transition from "for kicks" destructiveness to a tool for criminals
  • A move from transmission by floppy disk and email to transmission by a wide range of means, sometimes passive with no user involvement
  • The targeting of specific industries, companies, and government agencies
  • Rapid reproduction that allows malicious code to go global in a matter of minutes
  • The infestation of systems and platforms that were once isolated from such threats

The increase in the means of transmission represents the greatest obstacle to controlling the security threat. Email remains an important method of distribution for viruses and malicious code, but now employee laptop computers connected to the corporate network, VPN connections, iPods and PDAs, IM chat programs, file sharing programs, open ports, spyware and malware, and drive-by downloads by malicious Web pages can all serve as sources of infection. Unfortunately, many of these are important tools in day-to-day business and controlling them is increasingly difficult.

Add to this the new purpose of malicious code—which often is to steal sensitive personal or financial data or corporate information—and the face of the threat has changed significantly. Security measures must keep pace in order for today's companies to protect their assets, comply with regulatory legislation, and maintain consumer confidence.

An Evolving Threat—By the Numbers

A special report released by IBM's Global Security Intelligence Team earlier this year highlighted a number of key trends that illustrate how the virus and malicious code has evolved in the first half of 2005:

  • More than 35 million phishing attacks to steal critical data occurred in the first half of 2005.
  • "Spear phishing" increased more than ten-fold since January 2005.
  • Virus-laden email increased by 50% over the past six months.
  • One in every 28 emails is laden with a malicious security threat as of June 2005 (this is an increase from one in every 52 emails in December 2004).
  • Increased critical security events are occurring on Fridays and Sundays.
  • The ratio of spam to legitimate email decreased over the past six months, dropping from 83% spam in January to 67% spam in June, which, while appearing positive at first glance, signifies a shift in the delivery vehicles being used by attackers and highlights the fact that email is no longer the only front to fight in the battle against viruses.
  • Findings indicate growing financial, political, competitive, or social motivations behind attacks.
  • The total number of attacks in first half of 2005 was more than 237 million.

Corporations in the Crosshairs

The broad impact of malicious code, in which the attack is blindly released, is giving way to focused, targeted attacks with specific goals. Corporations in specific industries and government agencies are increasingly finding themselves in the crosshairs as attackers lock in on achieving financial, political, or competitive goals. Here are just a few examples:

  • In August 2005, Australian automaker Holden was hit by the Zotob worm and was forced to shut down its manufacturing facilities in Adelaide. As a result of the attack and forced shutdown, Holden lost $6 million (Australian) in auto production. At the same time, the Zotob worm also wreaked havoc on U.S. and Canadian businesses, including DaimlerChrysler, ABC News, CNN, The New York Times, and General Electric.
  • In May 2005, four major banks—Commerce Bank, PNC Bank, Wachovia, and Bank of America—had the financial records of some 700,000 customers stolen by bank employees and sold to collection agencies.
  • In April 2005, The National Hi-Tech Crime Unit of the British police reported that U.K. companies receive an average of seven viruses per day, and British Bank HSBC is the target of an average of seven attacks per day and has been hit with as many as 100,000 attacks in a single day.
  • In October 2004, police in Brazil arrested 53 people suspected of stealing $30 million through Internet fraud by delivering emails containing hidden Trojans to people over the Internet to record bank account access information. This type of theft can end up dealing banks serious losses when they must reimburse customers as a result of fraud protection.
  • In May 2004, in an attack that spanned industries, the Sasser worm caused major disruption of operations at British Airways and the British Coast Guard, among others, by causing systems to repeatedly quit or reboot without explanation. Sasser is significant in that it represented a new, insidious way of delivering malicious code by simply scanning systems from the Internet for a known security flaw and entering the system without any initiation by a user.
  • In January 2004, in a case of malicious code attacks being used for social/corporate reasons, the original MyDoom virus spread through email and file sharing with the intended goal of taking over machines in order to launch a denial-of-service (DoS) attack on the SCO Group. This successful attack grew out of anger over SCO's numerous lawsuits against companies and threats to users of UNIX code.

A special report released by IBM's Global Security Intelligence Team earlier this year outlined the most-targeted industries during the first half of 2005:

  • Government: 54 million+ attacks
  • Manufacturing: 36 million+ attacks
  • Financial Services: 34 million+ attacks
  • Healthcare: 17 million attacks

What Lies Beneath… and Beyond

So just how does one go about eradicating viruses and malicious code from the system? As mentioned earlier, simply scanning PCs with anti-virus software was at one time enough to keep things clean. But nowadays, malicious code can jump from system to system and platform to platform with ease. It can hide on platforms, such as System i or UNIX, that it does not so obviously affect and can use those platforms to launch attacks on more vulnerable platforms such as Windows and Linux. Like roaches, for every virus you see, there are likely hundreds—if not thousands—more lurking under the surface. Spraying poison along the baseboard will kill the roaches that come out into the open, but it won't get rid of the nest. The same holds true for viruses and malicious code.

But that's not the only threat to security. Worms like Sasser can scan your system remotely from the Internet and jump on whenever they find an unpatched security exposure. In this case, you're being attacked from the darkness beyond.

Patched programs can also represent a serious threat to the integrity of security. A consultant could install a root kit on your system without your knowledge in order to gain back door access in the future. Through this back door, that consultant could suck critical information out of the company for his own use. A third-party application that has been patched by the vendor to achieve a beneficial capability for the user could inadvertently compromise system security and open doors to malicious code.

And there's also the threat posed by improper access to data by those inside the company. Unscrupulous employees with excessive access to data could steal information from the company and pass it to competitors or sell it to others. Disgruntled employees could intentionally delete critical information.

Safety in Layers

All of these issues—hidden viruses, port-scanning worms, patched programs, hackers from outside the company, and insiders with ill intent—call for a more thorough security plan than has been required in the past. Architects of physical security have long understood the benefit of layers in achieving their protection goals. The same concept applies to system security in the computer world and is your best bet when it comes to combating viruses, malicious code, and the actions that can open doors to them.

Layer #1: The Firewall
Firewalls have long been an important element of corporate computing security, and they are now even commonplace in home computing environments. While firewalls do provide important protection, there is a common misconception that they provide an impenetrable wall around the computing environment and therefore are the first and the last step to security. A firewall will keep out casual intruders and provide protection against unwanted incoming traffic. It will not, however, prevent viruses, malicious code, or hacks that enter the environment via email, portable devices, secured connections, or insiders. Firewalls also will not prevent downloads from the Internet, which could introduce malicious code to the system. For that, additional layers are required.

Layer #2: User IDs and Passwords
Strong user IDs and passwords are the next layer of defense against attacks on system security. If a hacker, a virus, or other malicious code gains access to the system despite the firewall, these access controls can eliminate a large percentage of the risk now facing the system.

Layer #3: Access Control
User IDs and passwords can be compromised, so for those who manage to get past that protective layer, access control to data on the user level is critical. Network security applications can give you control over which files and folders a given user can access, thereby reducing the chance that someone who compromises a given user ID and password will gain access to the company's most sensitive and critical data. This layer also provides protection against threats originating from employees.

Layer #4: Scanning on All Systems
If a virus or malicious code makes it through the upper layers of your security and finds a home on the system, it is critical to quickly detect and immediately eradicate it and to do so on all systems that could host the code. This means that simply scanning PCs is not enough. If the virus is sitting on the iSeries, for example, but is surfacing on the PC, then cleaning only the PC means that you are treating the symptom but not curing the disease. If you have Windows PCs in your network, they all must have anti-virus software running. If you have an iSeries, it must have anti-virus software running. If you have Linux PCs, they must have anti-virus software running. Leaving any area unprotected can be counterproductive to the implementation of your other layers and could potentially defeat the overall goal of your security policy.

Layer #5: The Safety Net
Despite your best efforts, security breaches will occur. With a solid, layered approach to security, these breaches should be limited, but nevertheless you must have a last-ditch recovery plan in place. Daily backups are key, and supplemental software that can catch deleted files throughout the day can provide a thorough safety net that will allow you to easily recover any deleted data. This layer should also include an auditing process that examines the system and maintains a reasonable log that can be used to pinpoint the causes and results of a security breach to help prevent similar future occurrences.

Safe and Secure

Just as in the physical world, a multifaceted, layered approach to security will help you make your system safer and your company a shining example of modern IT security.

This article was originally published on MC Press Online and is reproduced here for portfolio purposes.