Functions Supporting Formatted Output

Many functions use the interpreter of formatted input and output. The list of such functions is not limited to the printf function, and they are not found only in console applications. Graphical applications and server-side parts of client/server applications running under Windows NT actively use the sprintf function that outputs formatted strings into the buffer.

Functions listed in Table 6.1 are not dangerous by themselves . The issue that makes them dangerous is the presence of the user input in the format argument. When searching for vulnerabilities in a program, hackers usually look for such code sections.

Table 6.1: Main functions for formatted input and output with brief descriptions

Function	Description
fprintf	ASCII	Formatted output into a file
fwprintf	UNICODE
fscanf	ASCII	Formatted input from the named input stream
fwscanf	UNICODE
printf	ASCII	Formatted output into stdout
wprintf	UNICODE
scanf	ASCII	Formatted input from stdin
wscanf	UNICODE
_snprintf	ASCII	Formatted output into the buffer with a length limitation
_snwprintf	UNICODE
sprintf	ASCII	Formatted output into a buffer
swprintf	UNICODE
sscanf	ASCII	Formatted input from a buffer
swscanf	UNICODE
vfprintf	ASCII	Formatted output into the named stream
vfwprintf	UNICODE
vprintf	ASCII	Formatted output into stdout
vwprintf	UNICODE
_vsnprintf	ASCII	Formatted output into a buffer with a length limitation
_vsnwprintf	UNICODE
vsprintf	ASCII	Formatted output into a buffer
vswprintf	UNICODE