computer A computer is a machine that can be programmed to Execution (computing), carry out sequences of arithmetic or logical operations (computation) automatically. Modern digital electronic computers can perform generic sets of operations known as C ...

software Software is a set of computer programs and associated documentation and data. This is in contrast to hardware, from which the system is built and which actually performs the work. At the lowest programming level, executable code consists ...

, a time bomb is part of a computer

program Program, programme, programmer, or programming may refer to: Business and management * Program management, the process of managing several related projects * Time management * Program, a part of planning Arts and entertainment Audio * Progra ...

that has been written so that it will start or stop functioning after a predetermined date or time is reached. The term "time bomb" does not refer to a program that stops functioning a specific number of days after it is installed; instead, the term "

trialware Shareware is a type of proprietary software that is initially shared by the owner for trial use at little or no cost. Often the software has limited functionality or incomplete documentation until the user sends payment to the software developer ...

" applies. Time bombs are commonly used in

beta Beta (, ; uppercase , lowercase , or cursive ; grc, βῆτα, bē̂ta or ell, βήτα, víta) is the second letter of the Greek alphabet. In the system of Greek numerals, it has a value of 2. In Modern Greek, it represents the voiced labiod ...

(pre-release) software when the manufacturer of the software does not want the beta version being used after the final release date. One example of time bomb software would be Microsoft's

Windows Vista Beta 2 The New product development, development of Windows Vista occurred over the span of five years, starting in earnest in May 2001, prior to the release of Microsoft's Windows XP operating system, and continuing until November 2006. Microsoft origin ...

, which was programmed to expire on May 31, 2007. The time limits on time bomb software are not usually as heavily enforced as they are on trial software, since time bomb software does not usually implement secure clock functions.

Comparison of logic bombs and time bombs

The main differences between

logic bomb A logic bomb is a piece of code intentionally inserted into a software system that will set off a malicious function when specified conditions are met. For example, a programmer may hide a piece of code that starts deleting files (such as a sala ...

s and time bombs is that a logic bomb may have a timing function implemented into it as a failsafe if the conditions are not met in a certain time period (it may delete itself or activate its payload using the timing system), while time bombs only use timing functions to (de)activate themselves. Time bombs, once activated, will unload their payload (which may be malicious) in a similar way logic bombs deliver their payloads to the target. The main difference between both time and logic bombs, and

fork bomb In computing, a fork bomb (also called rabbit virus or wabbit) is a denial-of-service attack wherein a process continually replicates itself to deplete available system resources, slowing down or crashing the system due to resource starvation. ...

s, is that a fork bomb has no payload ''per se'', and instead does its damage by continually replicating itself to deplete available system resources.

History

The first use of a time bomb in software may have been in 1979 with the

Scribe A scribe is a person who serves as a professional copyist, especially one who made copies of manuscripts before the invention of automatic printing. The profession of the scribe, previously widespread across cultures, lost most of its promi ...

markup language and word processing system, developed by Brian Reid. Reid sold Scribe to a software company called Unilogic (later renamed Scribe Systems), and agreed to insert a set of time-dependent functions (called "time bombs") that would deactivate freely copied versions of the program after a 90-day expiration date. To avoid deactivation, users paid the software company, which then issued a code that defused the internal time bomb feature.

Richard Stallman Richard Matthew Stallman (; born March 16, 1953), also known by his initials, rms, is an American free software movement activist and programmer. He campaigns for software to be distributed in such a manner that its users have the freedom to ...

saw this as a betrayal of the programmer ethos. Instead of honoring the notion of share-and-share alike, Reid had inserted a way for companies to compel programmers to pay for information access (see Events leading to GNU).

References

Software licenses {{compu-prog-stub

Comparison of logic bombs and time bombs

History

See also

References