What are logic bombs and time bombs?

A logic bomb is a malicious piece of code that gets executed when a certain condition is met. A simple example is a program that monitors the payroll system of a company and deletes critical files when a specific employee is terminated.

A time bomb is a logic bomb, the execution of which is triggered on a specific day or time, such as Valentine’s Day or 1st April.

Time bombs and logic bombs are malware that are used by attackers or disgruntled insiders for illegitimate purposes. They may embed the piece of code within a trojan or virus and use social engineering techniques to trick a user into installing the malware on his system. After that, the trojan or virus can spread itself silently. And, when a certain day or time appears, it can start alerting the users.

Attackers can also use logic bombs with spyware and steal sensitive information. The spyware can silently infect a computer when the user clicks on a suspicious link, opens suspicious email attachments, or installs software from untrusted sources. The spyware can install a keystroke logger on the system. And, when the user opens the web application of a bank, etc., to authenticate himself, the logic bomb may get triggered. It can silently log the keystrokes, steal sensitive information, and later transfer the data to the attacker silently.

Many times, logic bombs and time bombs are used by disgruntled employees to take revenge or for some other malicious purposes. Some popular examples include a Unix system administrator who got imprisoned for 30 months for inserting a logic bomb in Medco Health Solution Servers. And, an IT contractor, Fannie Mae, inserted a time bomb to attack corporate servers.

How to prevent logic bombs and time bombs?

There are some steps that can be taken to prevent these attacks.

• The principle of least privileges given to employees within an organization always helps in preventing these attacks.
• Do not click on suspicious links.
• Do not install any software from untrusted sources.
• Do not open any email attachments if you are not very sure of the authenticity of the sender.
• Keep your browser and other commonly used software updated with recent security patches. Most of the time malware infects a computer by taking advantage of the security vulnerabilities present in commonly used software.
• Use anti-malware programs from trusted sources and keep them updated with recent patches.
• Keep your Operating System updated with recent patches. This will reduce the known vulnerabilities present in the Operating System.

The above article gave a brief overview of Logic Bombs and Time Bombs. Readers who want to know more about how various malware and cyberattacks work can refer to the book “A Guide To Cyber Security.”