Tag: security

Questions Related to security

Multiple choice technology security

In this code, x is freed twice. What is the risk of this code?

x = malloc(200); 
/* do something with x */ 
free(x);  
/* do something else */ 
free(x);

This is a double free vulnerability and must be fixed.
The second call to free() will return an error.
There might be compiler warnings, but the program will run fine.
This is not a security issue.

Reveal answer Fill a bubble to check yourself

Multiple choice technology security

int main (int argc, char *argv[]){
    char chararray[3];
    int intarray[3];
    int i;
    strncpy(chararray, argv[1], sizeof(chararray) - 1);
    for (i=0;i&lt;=3; i++){ /*1*/   chararray[i]= getchar();
        intarray[i]=i*i;/*2*/
    }
}

Is there a vulnerability in this code? If yes, which line(s) (Line numbers are marked using comments /* */)?

1
2
1 & 2
No vulnerability

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Multiple choice technology security

The options show various uses of strncpy. Choose which use of strncpy is most secure while not wasting storage space at dst? Src is an untrusted input obtained from an external source.

Strncpy(dst,src,len(dst))
Strncpy(dst,src,len(src)+1)
Strncpy(dst,src,len(dst)+1)
Strncpy(dst,src,len(dst)-1)

Reveal answer Fill a bubble to check yourself

Multiple choice technology security

Which of the following is a secure way to use scanf?

scanf("%.8s", name);
scanf("%8s", name);
scanf("%8c", name);
scanf("%s", name);

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Multiple choice technology security

How do you fix the unbounded string copy in the following code?

char fname[20];   /* 1 */ 
cout &lt;&lt; “Enter First Name:”; /* 2 */ 
cin &gt;&gt; fname ;   /* 3 */

Replace cin call in line 3 with gets() function.
The length of input from cin cannot be limited. Use a larger array for fname.
Use cin.width[20] before line 3.
Use cin.size[19] before line 3.

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Multiple choice technology security

While trying to print an eight character long name, which of the following will introduce a security vulnerability ?

printf ("%.8s",name); /* 1 */
printf (name);  /* 2 */ 
printf ("%s",name);  /* 3 */ 
printf ("%8c", name);  /* 4 */

1 and 2
2 and 3
3 and 4
only 2

Reveal answer Fill a bubble to check yourself

Multiple choice technology security

int main(int argc,char* argv[]) {
    int *ptr1=new int;
    if(ptr1==NULL)    exit(1);
    int *ptr2=new int;
    if(ptr2==NULL)    exit(1);
    char* j;
    j=argv[1];
    int k=atoi(j);
    if (j==0){
        Ptr1=&amp;k;
        delete ptr2;  /*1*/
    }
    else {
        Ptr2=&amp;k;
    }
    delete ptr1;  /*2*/  
    delete ptr2; /*3*/   
    return 0;
}

which line of the code should be deleted to remove vulnerability

line 1 and line 3
line 2 and line 3
line 1
line 3

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Multiple choice technology security

char *name="32000"; What will be sizeof(name) return?

4 - it is the size of the pointer
5 - it is the number of characters in the string that the pointer points to
4 - it is the size when 32000 is stored as integer
1 - it is the size of a character variable

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Multiple choice technology security

int main(int argc,char* argv[]){
    int *ptr=new int;
    if(ptr==NULL)   exit(1);
    char *j;
    for(int i=1; i&lt;=4;  i++) {
        j=argv[i];
        int k=atoi(j);
        if (k!=0){
            *ptr=k;
            delete ptr;
        }
    }
}

Will this program execute successfully ?

program works when there is only 1 argument with program.
program works when there are 3 arguments with program.
program works when there are 4 arguments with program.
program never executes successfully.

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Multiple choice technology security

unsigned int i; 
scanf("%u",&amp;i);

With the size of unsigned integers being 4 bytes, What happens when a negative number is entered?

A run-time error is encountered and the program aborts.
unsigned int variables cannot store the sign (+ or -) of the number. The sign is discarded and only the number is stored in i.
A large positive number will be stored in i.
Unsigned int variables cannot store signed numbers. Hence in this program i will contain garbage values.

Reveal answer Fill a bubble to check yourself

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