Software security

[iam3]

I know nothing about C++...got this exercise in a course about security...can someone give me a hint??

#include <iostream>

main()
{
char command[40]; // Send command to
int time_of_day; // Avoid replay attack?
const bool ever = 1;

for ( ;ever; )
{
cin >> time_of_day >> command;
cout << &quot;Command was &quot; << command << &quot; at time &quot; << time_of_day << endl;
}
}

if we try input:
13 report
13 shoot-to-kill
15 shoot only if they shoot first
12:00 fire


how can someone perform a denial of service attack on this server? This same error was present in NT4, prior to service pack 2. This problem is difficult to fix with the C++ stream library, but easy to fix with C's I/O library:
#include <stdio.h>

#define ever 1

main()

{ char command[40]; // Send command to
int time_of_day; // Avoid replay attack?

for ( ;ever; )
{
scanf(&quot;%d %[^\n]&quot;,&time_of_day,command);
printf(&quot;Command %s at time %d\n&quot;,command,time_of_day);
}
}


The regular expression matcher %[^\n] means `match any object consisting of any character up to end of line'.
Why is it safer now?

 

[marsd]

The newline delimits the 40 char buffer.
Scanf is picky about what it will accept, unlike gets,
or evidently the c++ i/o stream.