掃描與抓包分析
3.1 問題
本案例要求熟悉Linux主機環境下的常用安全工具，完成以下任務操作：
- 使用NMAP掃描來獲取指定主機/網段的相關信息
- 使用EtterCAP截獲明文通信的密碼、檢測非加密通信的脆弱性
- 使用Tcpdump分析FTP訪問中的明文交換信息
3.2 方案
使用兩台RHEL6虛擬機，其中svr5作為掃描、嗅探、抓包的操作用機，而mail作為測試用的靶機；另外准備一台Windows客戶機pc120，也可以作為靶機
3.3 步驟
實現此案例需要按照如下步驟進行。
步驟一：使用NMAP掃描來獲取指定主機/網段的相關信息
1）檢查目標主機mail所開啟的TCP服務
[root@svr5 ~]# nmap 192.168.4.100 Starting Nmap 5.51 ( http://nmap.org ) at 2015-05-17 17:55 CST Nmap scan report for 192.168.4.100 Host is up (0.00028s latency). Not shown: 990 closed ports PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh 25/tcp open smtp 80/tcp open http 110/tcp open pop3 111/tcp open rpcbind 143/tcp open imap 443/tcp open https 993/tcp open imaps 995/tcp open pop3s MAC Address: 00:0C:29:74:BE:21 (VMware) Nmap done: 1 IP address (1 host up) scanned in 1.31 seconds
2）檢查192.168.4.0/24網段內哪些主機開啟了FTP、SSH服務
[root@svr5 ~]# nmap -p 21-22 192.168.4.0/24 Starting Nmap 5.51 ( http://nmap.org ) at 2015-05-17 18:00 CST Nmap scan report for 192.168.4.1 Host is up (0.000025s latency). PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh Nmap scan report for 192.168.4.5 Host is up. PORT STATE SERVICE 21/tcp filtered ftp 22/tcp filtered ssh Nmap scan report for 192.168.4.120 Host is up (0.00052s latency). PORT STATE SERVICE 21/tcp open ftp 22/tcp open ssh MAC Address: 00:0C:29:74:BE:21 (VMware) Nmap scan report for pc110.tarena.com (192.168.4.110) Host is up (0.00038s latency). PORT STATE SERVICE 21/tcp closed ftp 22/tcp closed ssh MAC Address: 00:50:56:C0:00:01 (VMware) Nmap scan report for 192.168.4.120 Host is up (0.00051s latency). PORT STATE SERVICE 21/tcp closed ftp 22/tcp closed ssh MAC Address: 00:0C:29:DB:84:46 (VMware) Nmap done: 256 IP addresses (5 hosts up) scanned in 4.88 seconds
3）檢查192.168.4.0/24網段內哪些主機可以ping通
[root@svr5 ~]# nmap -n -sP 192.168.4.0/24 Starting Nmap 5.51 ( http://nmap.org ) at 2015-05-17 18:01 CST Nmap scan report for 192.168.4.1 Host is up. Nmap scan report for 192.168.4.5 Host is up. Nmap scan report for 192.168.4.120 Host is up (0.00027s latency). MAC Address: 00:0C:29:74:BE:21 (VMware) Nmap scan report for 192.168.4.110 Host is up (0.00016s latency). MAC Address: 00:50:56:C0:00:01 (VMware) Nmap scan report for 192.168.4.120 Host is up (0.00046s latency). MAC Address: 00:0C:29:DB:84:46 (VMware) Nmap done: 256 IP addresses (5 hosts up) scanned in 3.57 seconds
4）全面分析目標主機192.168.4.100、192.168.4.120的操作系統信息
[root@svr5 ~]# nmap -A 192.168.4.100,120 Starting Nmap 5.51 ( http://nmap.org ) at 2015-05-17 18:03 CST Nmap scan report for 192.168.4.100 //主機mail的掃描報告 Host is up (0.0016s latency). Not shown: 990 closed ports PORT STATE SERVICE VERSION 21/tcp open ftp vsftpd 2.2.2 | ftp-anon: Anonymous FTP login allowed (FTP code 230) | -rw-r--r-- 1 0 0 1719 Aug 17 13:33 UserB.pub | -rw-r--r-- 1 0 0 122 Aug 13 05:27 dl.txt | drwxr-xr-x 2 14 0 4096 Aug 13 09:07 pub | -rw-rw-r-- 1 505 505 170 Aug 17 13:18 tools-1.2.3.tar.gz |_-rw-rw-r-- 1 505 505 287 Aug 17 13:22 tools-1.2.3.tar.gz.sig 22/tcp open ssh OpenSSH 5.3 (protocol 2.0) | ssh-hostkey: 1024 86:be:d6:89:c1:2d:d9:1f:57:2f:66:d1:af:a8:d3:c6 (DSA) |_2048 16:0a:15:01:fa:bb:91:1d:cc:ab:68:17:58:f9:49:4f (RSA) 25/tcp open smtp Postfix smtpd 80/tcp open http Apache httpd 2.2.15 ((Red Hat)) |_http-methods: No Allow or Public header in OPTIONS response (status code 302) | http-title: 302 Found |_Did not follow redirect to https://192.168.4.100// 110/tcp open pop3 Dovecot pop3d |_pop3-capabilities: USER CAPA UIDL TOP OK(K) RESP-CODES PIPELINING STLS SASL(PLAIN) 111/tcp open rpcbind 143/tcp open imap Dovecot imapd |_imap-capabilities: LOGIN-REFERRALS STARTTLS IMAP4rev1 ENABLE AUTH=PLAIN LITERAL+ IDLE SASL-IR ID 443/tcp open ssl/http Apache httpd 2.2.15 ((Red Hat)) | http-methods: Potentially risky methods: TRACE |_See http://nmap.org/nsedoc/scripts/http-methods.html |_http-title: Site doesn't have a title (text/html; charset=UTF-8). 993/tcp open ssl/imap Dovecot imapd |_imap-capabilities: IMAP4rev1 AUTH=PLAIN ENABLE ID LITERAL+ IDLE SASL-IR LOGIN-REFERRALS 995/tcp open ssl/pop3 Dovecot pop3d |_pop3-capabilities: OK(K) CAPA RESP-CODES UIDL PIPELINING USER TOP SASL(PLAIN) MAC Address: 00:0C:29:74:BE:21 (VMware) No exact OS matches for host (If you know what OS is running on it, see http://nmap.org/submit/ ). TCP/IP fingerprint: OS:SCAN(V=5.51%D=8/19%OT=21%CT=1%CU=34804%PV=Y%DS=1%DC=D%G=Y%M=000C29%TM=52 OS:11ED90%P=x86_64-redhat-linux-gnu)SEQ(SP=106%GCD=1%ISR=10B%TI=Z%CI=Z%II=I OS:%TS=A)OPS(O1=M5B4ST11NW6%O2=M5B4ST11NW6%O3=M5B4NNT11NW6%O4=M5B4ST11NW6%O OS:5=M5B4ST11NW6%O6=M5B4ST11)WIN(W1=3890%W2=3890%W3=3890%W4=3890%W5=3890%W6 OS:=3890)ECN(R=Y%DF=Y%T=40%W=3908%O=M5B4NNSNW6%CC=Y%Q=)T1(R=Y%DF=Y%T=40%S=O OS:%A=S+%F=AS%RD=0%Q=)T2(R=N)T3(R=N)T4(R=Y%DF=Y%T=40%W=0%S=A%A=Z%F=R%O=%RD= OS:0%Q=)T5(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)T6(R=Y%DF=Y%T=40%W=0% OS:S=A%A=Z%F=R%O=%RD=0%Q=)T7(R=Y%DF=Y%T=40%W=0%S=Z%A=S+%F=AR%O=%RD=0%Q=)U1( OS:R=Y%DF=N%T=40%IPL=164%UN=0%RIPL=G%RID=G%RIPCK=G%RUCK=G%RUD=G)IE(R=Y%DFI= OS:N%T=40%CD=S) Network Distance: 1 hop Service Info: Host: mail.tarena.com; OS: Unix TRACEROUTE HOP RTT ADDRESS 1 1.55 ms 192.168.4.100 Nmap scan report for 192.168.4.120 //主機pc120的掃描報告 Host is up (0.00047s latency). Not shown: 997 closed ports PORT STATE SERVICE VERSION 135/tcp open msrpc Microsoft Windows RPC 139/tcp open netbios-ssn 445/tcp open microsoft-ds Microsoft Windows XP microsoft-ds MAC Address: 00:0C:29:DB:84:46 (VMware) Device type: general purpose Running: Microsoft Windows XP OS details: Microsoft Windows XP SP2 - SP3 Network Distance: 1 hop Service Info: OS: Windows Host script results: |_nbstat: NetBIOS name: PC-201307130328, NetBIOS user: <unknown>, NetBIOS MAC: 00:0c:29:db:84:46 (VMware) |_smbv2-enabled: Server doesn't support SMBv2 protocol | smb-os-discovery: | OS: Windows XP (Windows 2000 LAN Manager) | Name: WORKGROUP\PC-201307130328 |_ System time: 2015-05-17 18:04:40 UTC+8 TRACEROUTE HOP RTT ADDRESS 1 0.47 ms 192.168.4.120 OS and Service detection performed. Please report any incorrect results at http://nmap.org/submit/ . Nmap done: 2 IP addresses (2 hosts up) scanned in 43.01 seconds
步驟二：使用EtterCAP截獲明文通信的密碼，檢測非加密通信的脆弱性
1）安裝EtterCAP嗅探工具
下載（或老師提供）軟件包ettercap、依賴包libnet，執行rpm安裝。
[root@svr5 ~]# cd /var/ftp/pub [root@svr5 ~]# rpm -ivh libnet-1.1.5-1.el6.x86_64.rpm\ > ettercap-0.7.5-3.el6.1.20120906gitc796e5.x86_64.rpm warning: libnet-1.1.5-1.el6.x86_64.rpm: Header V3 RSA/SHA256 Signature, key ID 0608b895: NOKEY Preparing... ########################################### [100%] 1:libnet ########################################### [ 50%] 2:ettercap ########################################### [100%]
2）EtterCAP工具的命令行模式
執行ettercap命令，嗅探主機192.168.4.120與主機192.168.4.100的FTP服務（21端口）之間的數據通信，收集用戶名、密碼信息。
[root@svr5 ~]# ettercap -Tzq /192.168.4.100//21 /192.168.4.120// ettercap 0.7.5 copyright 2001-2012 Ettercap Development Team Listening on: eth0 -> 00:0C:29:AA:77:15 192.168.4.5/255.255.255.0 fe80::20c:29ff:feaa:7715/64 SSL dissection needs a valid 'redir_command_on' script in the etter.conf file Privileges dropped to UID 65534 GID 65534... plugin ec_sslstrip.so cannot be loaded... 30 plugins 40 protocol dissectors 55 ports monitored 13861 mac vendor fingerprint 1766 tcp OS fingerprint 2183 known services Starting Unified sniffing... //進入標准監聽狀態 Text only Interface activated... Hit 'h' for inline help
處於監聽狀態以后，從測試機pc120訪問主機mail的vsftpd服務，如圖-10所示。
圖-10
然后查看執行中的ettercap命令行界面，將會發現收集到的用戶名、密碼信息。
.. .. Text only Interface activated... Hit 'h' for inline help FTP : 192.168.4.120:21 -> USER: mickey PASS: pwd123
3）EtterCAP工具的圖形模式
在GNOME桌面環境下， 執行ettercap -G即可打開窗口程序。選擇菜單“Sniffer”-->“Unified Sniffer”監聽，指定網卡eth0；然后添加兩個主機192.168.4.100、192.168.4.120作為嗅探目標（Targets），選擇“Start”-->“Sniffing“即可進入監聽狀態。
參考前面的測試操作，再次從客戶機pc120訪問主機mail的vsftpd服務。然后查看執行中的ettercap監聽窗口程序，同樣可以收集到用戶名、密碼信息，如圖-11所示。
圖-11
步驟三：使用Tcpdump分析FTP訪問中的明文交換信息
1）啟用tcpdump命令行抓包
執行tcpdump命令行，添加適當的過濾條件，只抓取訪問主機192.168.4.100的21端口的數據通信 ，並轉換為ASCII碼格式的易讀文本。
[root@svr5 ~]# tcpdump -A host 192.168.4.100 and tcp port 21 tcpdump: verbose output suppressed, use -v or -vv for full protocol decode listening on eth0, link-type EN10MB (Ethernet), capture size 65535 bytes .. .. //進入等待捕獲數據包的狀態
2）執行FTP訪問，並觀察tcpdump抓包結果
參考前面的測試操作，再次從客戶機pc120訪問主機mail的vsftpd服務。然后查看執行中tcpdump程序的輸出，仔細分析FTP連接的建立過程、確認收集到的用戶名和口令信息。
.. .. 18:47:25.964110 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [S], seq 1201822818, win 65535, options [mss 1460,nop,wscale 0,nop,nop,sackOK], length 0 E..4..@.@......x...d.*..G.\b........;............... 18:47:25.964268 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [S.], seq 2284929633, ack 1201822819, win 14600, options [mss 1460,nop,nop,sackOK,nop,wscale 6], length 0 E..4..@.@......d...x...*.1BaG.\c..9.7............... 18:47:25.964436 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [.], ack 1, win 65535, length 0 E..(..@.@.. ...x...d.*..G.\c.1BbP............. 18:47:25.967592 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [P.], seq 1:21, ack 1, win 229, length 20 E..<FJ@.@.jE...d...x...*.1BbG.\cP...V...220 (vsFTPd 2.2.2) 18:47:26.117057 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [.], ack 21, win 65515, length 0 E..(..@.@......x...d.*..G.\c.1BvP............. 18:47:27.960530 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [P.], seq 1:14, ack 21, win 65515, length 13 E..5..@.@......x...d.*..G.\c.1BvP.......USER mickey 18:47:27.960544 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [.], ack 14, win 229, length 0 E..(FK@.@.jX...d...x...*.1BvG.\pP............. 18:47:27.960783 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [P.], seq 21:55, ack 14, win 229, length 34 E..JFL@.@.j5...d...x...*.1BvG.\pP...i~..331 Please specify the password. 18:47:28.085168 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [.], ack 55, win 65481, length 0 E..(..@.@......x...d.*..G.\p.1B.P............. 18:47:29.657364 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [P.], seq 14:27, ack 55, win 65481, length 13 E..5..@.@......x...d.*..G.\p.1B.P.......PASS pwd123 18:47:29.696968 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [.], ack 27, win 229, length 0 E..(FM@.@.jV...d...x...*.1B.G.\}P............. 18:47:29.702671 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [P.], seq 55:78, ack 27, win 229, length 23 E..?FN@.@.j>...d...x...*.1B.G.\}P.......230 Login successful. 18:47:29.835258 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [.], ack 78, win 65458, length 0 E..(..@.@......x...d.*..G.\}.1B.P............. 18:47:31.716375 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [P.], seq 27:33, ack 78, win 65458, length 6 E.....@.@......x...d.*..G.\}.1B.P... ...QUIT 18:47:31.716532 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [.], ack 33, win 229, length 0 E..(FO@.@.jT...d...x...*.1B.G.\.P....}........ 18:47:31.716634 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [P.], seq 78:92, ack 33, win 229, length 14 E..6FP@.@.jE...d...x...*.1B.G.\.P.......221 Goodbye. 18:47:31.716677 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [F.], seq 92, ack 33, win 229, length 0 E..(FQ@.@.jR...d...x...*.1B.G.\.P....n........ 18:47:31.717053 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [.], ack 93, win 65444, length 0 E..(..@.@......x...d.*..G.\..1B.P............. 18:47:31.718796 IP 192.168.4.120.novation > 192.168.4.100.ftp: Flags [F.], seq 33, ack 93, win 65444, length 0 E..(..@.@......x...d.*..G.\..1B.P............. 18:47:31.719097 IP 192.168.4.100.ftp > 192.168.4.120.novation: Flags [.], ack 34, win 229, length 0 E..(..@.@......d...x...*.1B.G.\.P....m........