1.原因：本來在家正常休息了，我們放在上海託管機房的線上服務器突然蹦了遠程不了，服務啓動不了，然後讓上海機房重啓了一次，還是直接掛了，一直到我遠程上才行。
2.現象：遠程服務器發現出現這類信息
Hi, please view: 
http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files!
Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files!
Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files!
Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files!
Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files!
Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files!
登錄信息
然後***去了國外網站查看
Greetings,
Your server has been hacked and your files have been deleted.
Before they were deleted, we backed them up to a server we control.
You must send a total of 3 BTC to the address: 1B1oU6EdREYffif3**********
Failure to do so will result in your files being deleted after 5 days.
We may also leak your files.
You can e-mail [email protected] for support. We will not give any files before a payment has been made.
Goodbye!
發現被黑。
3.開始排查：
首先檢查日誌，以前做過安全運維，所以寫過類似於檢查命令和工具，開始一一排查。
#查看是否爲管理員增加或者修改
find / -type f -perm 4000
#顯示文件中查看是否存在系統以外的文件
rpm -Vf /bin/ls
rpm -Vf /usr/sbin/sshd
rpm -Vf /sbin/ifconfig
rpm -Vf /usr/sbin/lsof
#檢查系統是否有elf文件被替換
#在web目錄下運行
grep -r "getRuntime" ./
#查看是否有***
find . -type f -name "*.jsp" | xargs grep -i "getRuntime"
#運行的時候被連接或者被任何程序調用
find . -type f -name "*.jsp" | xargs grep -i "getHostAddress"
#返回ip地址字符串
find . -type f -name "*.jsp" | xargs grep -i "wscript.shell"
#創建WshShell對象可以運行程序、操作註冊表、創建快捷方式、訪問系統文件夾、管理環境變量
find . -type f -name "*.jsp" | xargs grep -i "gethostbyname"
#gethostbyname()返回對應於給定主機名的包含主機名字和地址信息的hostent結構指針
find . -type f -name "*.jsp" | xargs grep -i "bash"
#調用系統命令提權
find . -type f -name "*.jsp" | xargs grep -i "jspspy"
#Jsp***默認名字
find . -type f -name "*.jsp" | xargs grep -i "getParameter"
fgrep - R "admin_index.jsp" 20120702.log > log.txt
#檢查是否有非授權訪問管理日誌
#要進中間件所在日誌目錄運行命令
fgrep - R "and1=1"*.log>log.txt
fgrep - R "select "*.log>log.txt
fgrep - R "union "*.log>log.txt
fgrep - R "../../"*.log >log.txt
fgrep - R "Runtime"*.log >log.txt
fgrep - R "passwd"*.log >log.txt
#查看是否出現對應的記錄
fgrep - R "uname -a"*.log>log.txt
fgrep - R "id"*.log>log.txt
fgrep - R "ifconifg"*.log>log.txt
fgrep - R "ls -l"*.log>log.txt
#查看是否有shell***
#以root權限執行
cat /var/log/secure
#查看是否存在非授權的管理信息
tail -n 10 /var/log/secure
last cat /var/log/wtmp
cat /var/log/sulog
#查看是否有非授權的su命令
cat /var/log/cron
#查看計劃任務是否正常
tail -n 100 ~./bash_history | more
查看臨時目錄是否存在***者***時留下的殘餘文件
ls -la /tmp
ls -la /var/tmp
#如果存在.c .py .sh爲後綴的文件或者2進制elf文件。
檢查出有點類似於***的ip，只能猜測然後查看ip地址過濾出這個ip的訪問信息 並查看ip地址是那邊的
Apr 17 03:14:56 localhost sshd[11499]: warning: /etc/hosts.deny, line 14: missing ":" separator
Apr 17 03:15:01 localhost sshd[11499]: Address 46.214.146.198 maps to 46-214-146-198.next-gen.ro, but this does not map back to the address - POSSIBLE BREAK-IN ATTEMPT!
Apr 17 03:15:01 localhost sshd[11499]: Invalid user ubnt from 46.214.146.198
Apr 17 03:15:01 localhost sshd[11500]: input_userauth_request: invalid user ubnt
Apr 17 03:15:01 localhost sshd[11499]: pam_unix(sshd:auth): check pass; user unknown
Apr 17 03:15:01 localhost sshd[11499]: pam_unix(sshd:auth): authentication failure; logname= uid=0 euid=0 tty=ssh ruser= rhost=46.214.146.198
Apr 17 03:15:01 localhost sshd[11499]: pam_succeed_if(sshd:auth): error retrieving information about user ubnt
Apr 17 03:15:03 localhost sshd[11499]: Failed password for invalid user ubnt from 46.214.146.198 port 34989 ssh2
Apr 17 03:15:03 localhost sshd[11500]: Connection closed by 46.214.146.198
就是他了，查看歷史記錄
日誌發現 Invalid user ubnt from 46.214.146.198
歷史記錄和相關訪問日誌已經被刪除，痕跡清除。
安裝chrootkit檢查是否有rootkit mkdir chrootkit cd chrootkit/ wget ftp://ftp.pangeia.com.br/pub/seg/pac/chkrootkit.tar.gz tar zxvf chkrootkit.tar.gz cd chkrootkit-0.50/ ls yum install -y glibc-static make sense ./chkrootkit
發現檢查沒有異常
打開 vi /etc/motd 發現
[root@mall ~]# vi /etc/motd Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files! Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files! Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files! Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files! Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files! Hi, please view: http://pastie.org/pastes/10800563/text?key=hzzm4hk4ihwx1jfxzfizzq for further information in regards to your files!
查找不出後門也找不到相關命令，感覺思路受損，暈頭轉向。
最後查找下單天的web訪問日誌和相關ip訪問
發現一條命令讓我好奇，GET /cgi-bin/center.cgi?id=20 HTTP/1.1
並且有點異常
發現像目前最流行的bash shell 漏洞，測試一下，果然存在漏洞。
env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
[root@mall ~]# env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
vulnerable
this is a test
4.修復升級命令：
yum -y install yum-downloadonly
yum -y install bash-4.1.2-33.el6_7.1.x86_64.rpm
[root@mall tmp]# yum -y install bash-4.1.2-33.el6_7.1.x86_64.rpm
已加載插件：fastestmirror, security
設置安裝進程
診斷 bash-4.1.2-33.el6_7.1.x86_64.rpm: bash-4.1.2-33.el6_7.1.x86_64
bash-4.1.2-33.el6_7.1.x86_64.rpm 將作爲 bash-4.1.2-15.el6_4.x86_64 的更新
Loading mirror speeds from cached hostfile
* base: ftp.sjtu.edu.cn
* extras: mirrors.skyshe.cn
* updates: ftp.sjtu.edu.cn
解決依賴關係
--> 執行事務檢查
---> Package bash.x86_64 0:4.1.2-15.el6_4 will be 升級
---> Package bash.x86_64 0:4.1.2-33.el6_7.1 will be an update
--> 完成依賴關係計算
依賴關係解決
======================================================================================================================================================================================
總文件大小：3.0 M
下載軟件包：
運行 rpm_check_debug
執行事務測試
事務測試成功
執行事務
正在升級 : bash-4.1.2-33.el6_7.1.x86_64
清理 : bash-4.1.2-15.el6_4.x86_64
Verifying : bash-4.1.2-33.el6_7.1.x86_64
Verifying : bash-4.1.2-15.el6_4.x86_64
更新完畢:
bash.x86_64 0:4.1.2-33.el6_7.1
完畢！
重新測試
[root@mall tmp]# env x='() { :;}; echo vulnerable' bash -c "echo this is a test"
this is a test
5.完成後做了如下措施：
1.修改了系統賬號密碼。
2.修改了sshd端口爲2220。
3.修改nginx用戶nologin。
4.發現系統服務器存在bash嚴重漏洞 破殼漏洞(Shellshock)並修復。
5.更新完成後後面沒有發現被***或者服務器自動宕機現象。
6.漏洞被利用過程：
我發送GET請求–>目標服務器cgi路徑
目標服務器解析這個get請求，碰到UserAgent後面的參數，Bash解釋器就執行了後面的命令
7.Shellshock介紹
Shellshock，又稱Bashdoor，是在Unix中廣泛使用的Bash shell中的一個安全漏洞，首次於2014年9月24日公開。許多互聯網守護進程，如網頁服務器，使用bash來處理某些命令，從而允許***者在易受***的Bash版本上執行任意代碼。這可使***者在未授權的情況下訪問計算機系統。
8.相關文章：
http://zone.wooyun.org/content/15392
http://www.freebuf.com/articles/system/50707.html
http://bobao.360.cn/news/detail/408.html
http://hacker-falcon.blog.163.com/blog/static/23979900320148294531576/
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