隨著開源產品的越來越盛行，作為一個Linux運維工程師，能夠清晰地鑒別異常機器是否已經被入侵了顯得至關重要，個人結合自己的工作經歷，整理了幾種常見的機器被黑情況供參考
背景信息：以下情況是在CentOS 6.9的系統中查看的，其它Linux發行版類似
1.入侵者可能會刪除機器的日志信息，可以查看日志信息是否還存在或者是否被清空，相關命令示例：
[<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/anaconda4.0K /var/log/anaconda.ifcfg.log24K /var/log/anaconda.log28K /var/log/anaconda.program.log64K /var/log/anaconda.storage.log
2.入侵者可能創建一個新的存放用戶名及密碼文件，可以查看/etc/passwd及/etc/shadow文件，相關命令示例：
[<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.入侵者可能修改用戶名及密碼文件，可以查看/etc/passwd及/etc/shadow文件內容進行鑒別，相關命令示例：
[<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/passwdroot:x:0:0:root:/root:/bin/bashbin:x:1:1:bin:/bin:/sbin/nologindaemon: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/shadowroot:*LOCK*:14600::::::bin:*:17246:0:99999:7:::daemon:*:17246:0:99999:7:::
4.查看機器最近成功登陸的事件和最后一次不成功的登陸事件，對應日志“/var/log/lastlog”，相關命令示例：
[<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> ~]# lastlogUsername Port From Latestroot **Never logged in**bin **Never logged in**daemon **Never logged in**
5.查看機器當前登錄的全部用戶，對應日志文件“/var/run/utmp”，相關命令示例：
[<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> ~]# whostone pts/0 2017-09-20 16:17 (X.X.X.X)test01 pts/2 2017-09-20 16:47 (X.X.X.X)
6.查看機器創建以來登陸過的用戶，對應日志文件“/var/log/wtmp”，相關命令示例：
[<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> ~]# lasttest01 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.查看機器所有用戶的連接時間（小時），對應日志文件“/var/log/wtmp”，相關命令示例：
[<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 11.98Sep 15 total 11.98 stone 67.06Sep 18 total 67.06 stone 1.27 test01 0.24Today total 1.50
8.如果發現機器產生了異常流量，可以使用命令“tcpdump”抓取網絡包查看流量情況或者使用工具”iperf”查看流量情況
9.可以查看/var/log/secure日志文件，嘗試發現入侵者的信息，相關命令示例：
[<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 ssh2Sep 20 16:17:47 hlmcen69n3 sshd[38206]: Accepted password for stone from X.X.X.X port 9140 ssh2Sep 20 16:46:00 hlmcen69n3 sshd[38511]: Accepted password for stone from X.X.X.X port 2540 ssh2Sep 20 16:47:16 hlmcen69n3 sshd[38605]: Accepted password for test01 from X.X.X.X port 10790 ssh2Sep 20 16:50:04 hlmcen69n3 sshd[38652]: Accepted password for test01 from X.X.X.X port 28956 ssh2
10.查詢異常進程所對應的執行腳本文件
a.top命令查看異常進程對應的PID
b.在虛擬文件系統目錄查找該進程的可執行文件
[<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 exelrwxrwxrwx. 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.如果確認機器已經被入侵，重要文件已經被刪除，可以嘗試找回被刪除的文件
Note：
1>當進程打開了某個文件時，只要該進程保持打開該文件，即使將其刪除，它依然存在于磁盤中。這意味著，進程并不知道文件已經被刪除，它仍然可以向打開該文件時提供給它的文件描述符進行讀取和寫入。除了該進程之外，這個文件是不可見的，因為已經刪除了其相應的目錄索引節點。
2>在/proc 目錄下，其中包含了反映內核和進程樹的各種文件。/proc目錄掛載的是在內存中所映射的一塊區域，所以這些文件和目錄并不存在于磁盤中，因此當我們對這些文件進行讀取和寫入時，實際上是在從內存中獲取相關信息。大多數與 lsof 相關的信息都存儲于以進程的 PID 命名的目錄中，即 /proc/1234 中包含的是 PID 為 1234 的進程的信息。每個進程目錄中存在著各種文件，它們可以使得應用程序簡單地了解進程的內存空間、文件描述符列表、指向磁盤上的文件的符號鏈接和其他系統信息。lsof 程序使用該信息和其他關于內核內部狀態的信息來產生其輸出。所以lsof 可以顯示進程的文件描述符和相關的文件名等信息。也就是我們通過訪問進程的文件描述符可以找到該文件的相關信息。
3>當系統中的某個文件被意外地刪除了，只要這個時候系統中還有進程正在訪問該文件，那么我們就可以通過lsof從/proc目錄下恢復該文件的內容。
假設入侵者將/var/log/secure文件刪除掉了，嘗試將/var/log/secure文件恢復的方法可以參考如下：
a.查看/var/log/secure文件，發現已經沒有該文件
[<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/securels: cannot access /var/log/secure: No such file or directory
b.使用lsof命令查看當前是否有進程打開/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/securersyslogd 1264 root 4w REG 8,1 3173904 263917 /var/log/secure (deleted)
c.從上面的信息可以看到 PID 1264（rsyslogd）打開文件的文件描述符為4。同時還可以看到/var/log/ secure已經標記為被刪除了。因此我們可以在/proc/1264/fd/4（fd下的每個以數字命名的文件表示進程對應的文件描述符）中查看相應的信息，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/4Sep 20 16:47:21 hlmcen69n3 sshd[38511]: pam_unix(sshd:session): session closed for user stoneSep 20 16:47:21 hlmcen69n3 su: pam_unix(su-l:session): session closed for user rootSep 20 16:49:30 hlmcen69n3 sshd[38605]: pam_unix(sshd:session): session closed for user test01Sep 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 ssh2Sep 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=rootSep 20 17:18:52 hlmcen69n3 sshd[38789]: Failed password for root from 51.15.81.90 port 47014 ssh2Sep 20 17:18:52 hlmcen69n3 sshd[38790]: Connection closed by 51.15.81.90
d.從上面的信息可以看出，查看/proc/1264/fd/4就可以得到所要恢復的數據。如果可以通過文件描述符查看相應的數據，那么就可以使用I/O重定向將其重定向到文件中，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，發現該文件已經存在。對于許多應用程序，尤其是日志文件和數據庫，這種恢復刪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/secureSep 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=rootSep 17 03:28:17 hlmcen69n3 sshd[13288]: Failed password for root from 51.15.64.137 port 59498 ssh2Sep 17 03:28:18 hlmcen69n3 sshd[13289]: Received disconnect from 51.15.64.137: 11: Bye ByeSep 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=rootSep 17 03:28:24 hlmcen69n3 sshd[13291]: Failed password for root from 51.15.64.137 port 37722 ssh2Sep 17 03:28:25 hlmcen69n3 sshd[13292]: Received disconnect from 51.15.64.137: 11: Bye Bye
總結
以上所述是小編給大家介紹的Linux服務器被黑以后的詳細處理步驟，希望對大家有所幫助，如果大家有任何疑問請給我留言，小編會及時回復大家的。在此也非常感謝大家對VEVB武林網網站的支持！
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