Chapter 8. Open Source Honeyclient: Proactive Detection of Client-Side Exploits
Client software vulnerabilities are currently being exploited at an increasing rate. Based on a September 2004 survey, Dell Computers estimates that 90% of Windows PCs harbor at least one spyware program. Microsoft’s Internet Explorer browser has had over 50 vulnerabilities in the past six months, according to the Common Vulnerabilities and Exposures (CVE) database. By taking advantage of client software vulnerabilities, attackers are able to infect and control systems that are protected by firewalls or otherwise inaccessible.
As is well known, client-side exploits can be used by the attacker for many other malicious activities once a victim machine is compromised. The exploit could steal valuable information, such as the user’s online banking credentials. Among other things, the attacker could hijack the victim machine and add it to growing bot networks, in which each bot becomes part of a distributed denial of service (DDoS) attack or a spam delivery system.
How will attackers utilize client software vulnerabilities? As far back as 2002, a paper titled How to 0wn the Internet In Your Spare Time came up with a disturbing possible scenario: a contagion worm exploit that targets both server and client vulnerabilities. First, the attack uses typical Web server security flaws, such as buffer overflows or SQL injection, to upload malicious code that is then downloaded whenever a targeted browser ...