DDR爱好者之家 Design By 杰米
随着开源产品的越来越盛行，作为一个Linux运维工程师，能够清晰地鉴别异常机器是否已经被入侵了显得至关重要，个人结合自己的工作经历，整理了几种常见的机器被黑情况供参考
背景信息：以下情况是在CentOS 6.9的系统中查看的，其它Linux发行版类似
1.入侵者可能会删除机器的日志信息，可以查看日志信息是否还存在或者是否被清空，相关命令示例：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="98eaf7f7ecd8f0f4f5fbfdf6aea1f6ab">[email protected]</a> ~]# ll -h /var/log/* -rw-------. 1 root root 2.6K Jul 7 18:31 /var/log/anaconda.ifcfg.log -rw-------. 1 root root 23K Jul 7 18:31 /var/log/anaconda.log -rw-------. 1 root root 26K Jul 7 18:31 /var/log/anaconda.program.log -rw-------. 1 root root 63K Jul 7 18:31 /var/log/anaconda.storage.log [<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="493b26263d092125242a2c277f70277a">[email protected]</a> ~]# du -sh /var/log/* 8.0K /var/log/anaconda 4.0K /var/log/anaconda.ifcfg.log 24K /var/log/anaconda.log 28K /var/log/anaconda.program.log 64K /var/log/anaconda.storage.log
2.入侵者可能创建一个新的存放用户名及密码文件，可以查看/etc/passwd及/etc/shadow文件，相关命令示例：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="80f2efeff4c0e8ecede3e5eeb6b9eeb3">[email protected]</a> ~]# ll /etc/pass* -rw-r--r--. 1 root root 1373 Sep 15 11:36 /etc/passwd -rw-r--r--. 1 root root 1373 Sep 15 11:36 /etc/passwd- [<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="c8baa7a7bc88a0a4a5abada6fef1a6fb">[email protected]</a> ~]# ll /etc/sha* ----------. 1 root root 816 Sep 15 11:36 /etc/shadow ----------. 1 root root 718 Sep 15 11:36 /etc/shadow-
3.入侵者可能修改用户名及密码文件，可以查看/etc/passwd及/etc/shadow文件内容进行鉴别，相关命令示例：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="9ceef3f3e8dcf4f0f1fff9f2aaa5f2af">[email protected]</a> ~]# more /etc/passwd root:x:0:0:root:/root:/bin/bash bin:x:1:1:bin:/bin:/sbin/nologin daemon:x:2:2:daemon:/sbin:/sbin/nologin [<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="20524f4f5460484c4d43454e16194e13">[email protected]</a> ~]# more /etc/shadow root:*LOCK*:14600:::::: bin:*:17246:0:99999:7::: daemon:*:17246:0:99999:7:::
4.查看机器最近成功登陆的事件和最后一次不成功的登陆事件，对应日志“/var/log/lastlog”，相关命令示例：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="4e3c21213a0e2622232d2b207877207d">[email protected]</a> ~]# lastlog Username Port From Latest root **Never logged in** bin **Never logged in** daemon **Never logged in**
5.查看机器当前登录的全部用户，对应日志文件“/var/run/utmp”，相关命令示例：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="c3b1acacb783abafaea0a6adf5faadf0">[email protected]</a> ~]# who stone pts/0 2017-09-20 16:17 (X.X.X.X) test01 pts/2 2017-09-20 16:47 (X.X.X.X)
6.查看机器创建以来登陆过的用户，对应日志文件“/var/log/wtmp”，相关命令示例：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="ec9e838398ac8480818f8982dad582df">[email protected]</a> ~]# last test01 pts/1 X.X.X.X Wed Sep 20 16:50 still logged in test01 pts/2 X.X.X.X Wed Sep 20 16:47 - 16:49 (00:02) stone pts/1 X.X.X.X Wed Sep 20 16:46 - 16:47 (00:01) stone pts/0 X.X.X.X Wed Sep 20 16:17 still logged in
7.查看机器所有用户的连接时间（小时），对应日志文件“/var/log/wtmp”，相关命令示例：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="03716c6c77436b6f6e60666d353a6d30">[email protected]</a> ~]# ac -dp
stone 11.98
Sep 15 total 11.98
stone 67.06
Sep 18 total 67.06
stone 1.27
test01 0.24
Today total 1.50
8.如果发现机器产生了异常流量，可以使用命令“tcpdump”抓取网络包查看流量情况或者使用工具”iperf”查看流量情况
9.可以查看/var/log/secure日志文件，尝试发现入侵者的信息，相关命令示例：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="82f0ededf6c2eaeeefe1e7ecb4bbecb1">[email protected]</a> ~]# cat /var/log/secure | grep -i "accepted password" Sep 20 12:47:20 hlmcen69n3 sshd[37193]: Accepted password for stone from X.X.X.X port 15898 ssh2 Sep 20 16:17:47 hlmcen69n3 sshd[38206]: Accepted password for stone from X.X.X.X port 9140 ssh2 Sep 20 16:46:00 hlmcen69n3 sshd[38511]: Accepted password for stone from X.X.X.X port 2540 ssh2 Sep 20 16:47:16 hlmcen69n3 sshd[38605]: Accepted password for test01 from X.X.X.X port 10790 ssh2 Sep 20 16:50:04 hlmcen69n3 sshd[38652]: Accepted password for test01 from X.X.X.X port 28956 ssh2
10.查询异常进程所对应的执行脚本文件
a.top命令查看异常进程对应的PID
b.在虚拟文件系统目录查找该进程的可执行文件
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="285a47475c684044454b4d461e11461b">[email protected]</a> ~]# ll /proc/1850/ | grep -i exe lrwxrwxrwx. 1 root root 0 Sep 15 12:31 exe -> /usr/bin/python [<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="1d6f7272695d7571707e78732b24732e">[email protected]</a> ~]# ll /usr/bin/python -rwxr-xr-x. 2 root root 9032 Aug 18 2016 /usr/bin/python
11.如果确认机器已经被入侵，重要文件已经被删除，可以尝试找回被删除的文件
Note：
1>当进程打开了某个文件时，只要该进程保持打开该文件，即使将其删除，它依然存在于磁盘中。这意味着，进程并不知道文件已经被删除，它仍然可以向打开该文件时提供给它的文件描述符进行读取和写入。除了该进程之外，这个文件是不可见的，因为已经删除了其相应的目录索引节点。
2>在/proc 目录下，其中包含了反映内核和进程树的各种文件。/proc目录挂载的是在内存中所映射的一块区域，所以这些文件和目录并不存在于磁盘中，因此当我们对这些文件进行读取和写入时，实际上是在从内存中获取相关信息。大多数与 lsof 相关的信息都存储于以进程的 PID 命名的目录中，即 /proc/1234 中包含的是 PID 为 1234 的进程的信息。每个进程目录中存在着各种文件，它们可以使得应用程序简单地了解进程的内存空间、文件描述符列表、指向磁盘上的文件的符号链接和其他系统信息。lsof 程序使用该信息和其他关于内核内部状态的信息来产生其输出。所以lsof 可以显示进程的文件描述符和相关的文件名等信息。也就是我们通过访问进程的文件描述符可以找到该文件的相关信息。
3>当系统中的某个文件被意外地删除了，只要这个时候系统中还有进程正在访问该文件，那么我们就可以通过lsof从/proc目录下恢复该文件的内容。
假设入侵者将/var/log/secure文件删除掉了，尝试将/var/log/secure文件恢复的方法可以参考如下：
a.查看/var/log/secure文件，发现已经没有该文件
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="20524f4f5460484c4d43454e16194e13">[email protected]</a> ~]# ll /var/log/secure ls: cannot access /var/log/secure: No such file or directory
b.使用lsof命令查看当前是否有进程打开/var/log/secure，
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="deacb1b1aa9eb6b2b3bdbbb0e8e7b0ed">[email protected]</a> ~]# lsof | grep /var/log/secure rsyslogd 1264 root 4w REG 8,1 3173904 263917 /var/log/secure (deleted)
c.从上面的信息可以看到 PID 1264（rsyslogd）打开文件的文件描述符为4。同时还可以看到/var/log/ secure已经标记为被删除了。因此我们可以在/proc/1264/fd/4（fd下的每个以数字命名的文件表示进程对应的文件描述符）中查看相应的信息，如下：
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="9deff2f2e9ddf5f1f0fef8f3aba4f3ae">[email protected]</a> ~]# tail /proc/1264/fd/4 Sep 20 16:47:21 hlmcen69n3 sshd[38511]: pam_unix(sshd:session): session closed for user stone Sep 20 16:47:21 hlmcen69n3 su: pam_unix(su-l:session): session closed for user root Sep 20 16:49:30 hlmcen69n3 sshd[38605]: pam_unix(sshd:session): session closed for user test01 Sep 20 16:50:04 hlmcen69n3 sshd[38652]: reverse mapping checking getaddrinfo for 190.78.120.106.static.bjtelecom.net [106.120.78.190] failed - POSSIBLE BREAK-IN ATTEMPT! Sep 20 16:50:04 hlmcen69n3 sshd[38652]: Accepted password for test01 from 106.120.78.190 port 28956 ssh2 Sep 20 16:50:05 hlmcen69n3 sshd[38652]: pam_unix(sshd:session): session opened for user test01 by (uid=0) Sep 20 17:18:51 hlmcen69n3 unix_chkpwd[38793]: password check failed for user (root) Sep 20 17:18:51 hlmcen69n3 sshd[38789]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=51.15.81.90 user=root Sep 20 17:18:52 hlmcen69n3 sshd[38789]: Failed password for root from 51.15.81.90 port 47014 ssh2 Sep 20 17:18:52 hlmcen69n3 sshd[38790]: Connection closed by 51.15.81.90
d.从上面的信息可以看出，查看/proc/1264/fd/4就可以得到所要恢复的数据。如果可以通过文件描述符查看相应的数据，那么就可以使用I/O重定向将其重定向到文件中，如:
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="8bf9e4e4ffcbe3e7e6e8eee5bdb2e5b8">[email protected]</a> ~]# cat /proc/1264/fd/4 > /var/log/secure
e.再次查看/var/log/secure，发现该文件已经存在。对于许多应用程序，尤其是日志文件和数据库，这种恢复删除文件的方法非常有用。
[<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="63110c0c17230b0f0e00060d555a0d50">[email protected]</a> ~]# ll /var/log/secure -rw-r--r--. 1 root root 3173904 Sep 20 17:24 /var/log/secure [<a href="/cdn-cgi/l/email-protection" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" rel="external nofollow" data-cfemail="ec9e838398ac8480818f8982dad582df">[email protected]</a> ~]# head /var/log/secure Sep 17 03:28:15 hlmcen69n3 sshd[13288]: reverse mapping checking getaddrinfo for 137-64-15-51.rev.cloud.scaleway.com [51.15.64.137] failed - POSSIBLE BREAK-IN ATTEMPT! Sep 17 03:28:15 hlmcen69n3 unix_chkpwd[13290]: password check failed for user (root) Sep 17 03:28:15 hlmcen69n3 sshd[13288]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=51.15.64.137 user=root Sep 17 03:28:17 hlmcen69n3 sshd[13288]: Failed password for root from 51.15.64.137 port 59498 ssh2 Sep 17 03:28:18 hlmcen69n3 sshd[13289]: Received disconnect from 51.15.64.137: 11: Bye Bye Sep 17 03:28:22 hlmcen69n3 sshd[13291]: reverse mapping checking getaddrinfo for 137-64-15-51.rev.cloud.scaleway.com [51.15.64.137] failed - POSSIBLE BREAK-IN ATTEMPT! Sep 17 03:28:22 hlmcen69n3 unix_chkpwd[13293]: password check failed for user (root) Sep 17 03:28:22 hlmcen69n3 sshd[13291]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=51.15.64.137 user=root Sep 17 03:28:24 hlmcen69n3 sshd[13291]: Failed password for root from 51.15.64.137 port 37722 ssh2 Sep 17 03:28:25 hlmcen69n3 sshd[13292]: Received disconnect from 51.15.64.137: 11: Bye Bye
总结
以上所述是小编给大家介绍的Linux服务器被黑以后的详细处理步骤，希望对大家有所帮助，如果大家有任何疑问请给我留言，小编会及时回复大家的。在此也非常感谢大家对网站的支持！
DDR爱好者之家 Design By 杰米
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DDR爱好者之家 Design By 杰米
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