Uncontrolled format string: Difference between revisions

Revision as of 15:13, 4 June 2023

Revision as of 13:56, 21 December 2023

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{{Short description|Type of software vulnerability}}

{{Use dmy dates|date=August 2019|cs1-dates=y}}

'''Uncontrolled format string''' is a type of [[code injection]] [[software vulnerability|vulnerability]] discovered around 1989 that can be used in [[security exploit]]s.<ref name="CWE134"/> Originally thought harmless, format string exploits can be used to [[Crash (computing)|crash]] a program or to execute harmful code. The problem stems from the use of [[unchecked user input]] as the [[format string]] parameter in certain [[C (programming language)|C]] functions that perform formatting, such as <code>[[Printf|printf()]]</code>. A malicious user may use the <code>%s</code> and <code>%x</code> format tokens, among others, to print data from the [[call stack]] or possibly other locations in memory. One may also write arbitrary data to arbitrary locations using the <code>%n</code> format token, which commands <code>printf()</code> and similar functions to write the number of bytes formatted to an address stored on the stack.

==Details==