Let’s try to run WCE using the -w option. Note that you must be a priveliged user to run this tool.

It’s pretty simple: WCE shows every passwords cached; in clear text.
Let’s assume that the pc CLI01 is joined to a domain and let’s see what happen if some service is started using domain admin password:

WOW! The domain admin password stored locally is showed.

How many service are misconfigured in your network? Let’s hope very few because you are a very good sysadmin and no service starts with domain sensitive password, but what about social engeneering?
Each time a user is begging for a password for an installation or he asks to you something that leads to digit your admin password on his pc, is it a legittimate request or does he wants your password cached?
So, you domain admin, what kind of password do you use on company users pc? The domain-admin-super-God password or the local pc password?

Basing ourselves on this and the previous post let’s now compile an hypothetical roadmap from simple user to domain admin:
1- Boot the company Microsoft PC using a CD/DVD with a bootable operating System
2- Use the sethc “feature” to become local admin
3- Begging for a domain admin password (“Please I need the latest java update, but I need your password”, “I’m trying to add a new charset, but the pc is asking for an admin password…”)
4- Run WCE and become domain admin
5- Use some other tool like pstool and collect the password of every user of the network

I think that these are the defences that a network/system admin can adopt:
1- No external device boot allowed and PC and case locked
2- No remediation on this (may be some domain policy). Remember that also Linux has a level 1 booting.
3- Users are invasive and dangerous, even if they don’t want your password. So Always log on their PCs always with the lowest privileges you can.
4- WCE must blocked to users (AV rule, policy, firewall)
5- If an attacker reach this point you will probably spend the next weeks searching another job in another city

The scope of this post is to make system admininistrators and everyone else aware on how to take care about IT security.
Many times, working as sysadmin, we make mistakes, we are pressured and we sometimes left open ports saying “I will patch them later”, but we always have to remember what risks we are taking.
An attack, talking about computer and network, often starts from the bottom and, little by little, try to reach the top; a small door open gives the way for another gate an so on. This process is called Privilege Escalation.

The Password Attacks on Kali Linux [Part 2]

Offline Password attack
The service that use as authentication a keyword needs to store it somewhere and somehow. Think about /etc/shadow or SAM in Windows, but also browsers, routers, switches and any kind of client (ftp, e-mail, smb). The password can be stored in clear text, in databases or hashed in files; every time you copy these files and then you try, even in other environment, to extract the passwords you are doing an offline password attack. With administrative rights is possible, for example, to dump password hash from Windows and Linux system. The same operation can be done mounting the target system disk on the Kali system, also without credentials, or starting the system to attack using a bootable Kali distribution.
Files that contain hashed or plaintext passwords can be found in every place: sometimes the database backup is directly hosted in a web folder, let alone files named password.txt that can be found directly using Google; also htaccess and htpasswd can be dumped sometimes. FTP client, zip files, RDP connection files are a mine of keywords easy to collect too. Sniffing traffic waiting for a pop3/ snmp clear-text request or taking a 4 way handshake from an access point are just other options you have to perform an offline attack.
Remember that keys are often reused throughout the network, so a complex password simply sniffed with Wireshark in a not encrypted packet like pop3 (see Figure 1) can be the same unbreakable and encrypted 15-chars password used for ssh service.

Figure 1

Windows SAM file and Linux shadow
Windows stores the hash of local passwords in a file named SAM “Security Accounts Manager” present in c:\windows\system32\config\. Of course the file isn’t plain text, but it has to be merged to another file (SYSTEM) present in the same folder. The union of these two files leads to a readable one where you can see the passwords hash just like thise in Figure 2.
These two files can be accessed only when the operating system is down or using tolls like PWdump or FGdump. The other choice is to dump the system backup of these; in fact, up to Windows Vista, you can find them in c:\windows\repair\ folder. To merge the SAM and the SYSTEM file you can use bkhive and samdump2; after getting the hash, John the Ripper is used to extract the password.

As said previousely, if you own the target machine, you can take advantage of tools like FGdump too or, if you have established a meterpreter session, of the hashdump command (see Figure 2).

Figure 2

Note that you need to be Admin or System to launch these commands and you have to upload to the target machine some lines of code that sometimes can be blocked by antivirus.
Since it’s one of the “most wanted” tools, let’s see also JtR in action:

Note that most passwords are immediately decrypted (nina, administrator, user, jasmine, albert, peru) when others only in part.
This is caused by the old windows method to store password called LM. This kind of hashing, putted next to the newer NTLMv2, is present by default up to Vista to guarantee the backward compatibility. LM can be disabled and Microsoft recommended that, but de facto this is a vulnerability that users are carrying on for many years.
The LM hash works as follow:
• the user password is converted in an all upper case string;
• the password is cutted after 14 bytes (max password length);
• the password is splitted in 2 pieces of 7 bytes max;
• this two pieces are encoded using DES.
This is a simple view of what is LM, but your interest is that JtR has the task to crack an hash with no more than 7 chars-upper-case. This is really different from finding a key with 14 chars, upper and lower case. in addition to this DES kind of encrypting is well known and john use this to speed up the work.

Also, Linux stores keys in two files: /etc/passwd and /etc/shadow. In this case it’s not essential the merge of the two files, but it’s better for decrypting. You can use the JtR command unshadow to join the two.
In Kali Linux you will be able to call any tool from anywhere on the system as every application is included in the system path so you can call unshadow and john just like this:

Then you use john to decrypt:

Sometimes you can try to use john on /etc/shadow without unshadowing it, but in this case john will not use the GECOS info (complete name, telephone number…) that helps to perform a better crack. Also the use of some features like -shells will be lost if you don’t perform the unshadow.

Some small words about using Google as hash cracker.
Google is a big container of everything. It’s not unusual to take an encrypted string, paste it in the browser and find the key.
One of the easiest hash to find is the MD5 one. The Message Digest algorithm 5 is an old method of hashing; it is already obsolete and insecure, but users and programs still employ it to encode passwords. If you try to paste an MD5 string in Google you’ll likely find it. Before trying everything else paste the hash in the search engine or use some online rainbowtable program.

The cache and the sniffing
Although the cache and the packet analysis are not pure offline password attacks, they deserve to be mentioned. If you finally own a PC in the net you have to test, squeeze it. Extract all what you are able to take.
First start a sniffing session using Wireshark or, if you can’t, use Ettercap to perform a man in the middle and wait for unencrypted password. These are some normalized output of Ettercap. The first is the capture of a webmail account on an insecure http page instead of more secure https:

Then some capture of POP3 and FTP packets:

This is why is always better to use an ssl version of all protocols, also in internal communications.

If you have access to a PC search for client’s programs like FileZilla or browsers and take note of passwords archived using meterpreter or search in Internet where the client stores it:

Then use ms-cache option of JtR or program like Windows Credentials Editor that locate system cached password: if you are lucky a sysadmin has been logged or some service is misconfigured and the password is stored (not encoded) in the cache.
In the following case of study the user HP\Nina, present in Domain Administrators group, is simply logged on. In this machine is present an agent misconfigured that use HP\administrator credential to work:

Note that cache keys “ninaanin” and “password” are not encoded.

SMB pass-the-hash
Like in the previous example, not always you’ll have to spend time in decrypting operations. Sometimes you can use the hash you get as it is. Ok, you can’t take the string and just paste it in a authentication window request and login using Remote Desktop, but there is a quite controversial feature in Windows on the authentication management of shared folders.

Consider this example:
Computer A has a c:\share and Computer B tries to connect to that share. B sends its credential in hash format (“hello! I am Administrator and my password is e52cac67419a9a224a3b108f3fa6cb6d”) and A verify if it has this credential, if so it connects Computer B to the share. If not it prompts for username and password.
All this process is in clear text!
So, what about If the Computer A is an attacker and has a network sniffer? It collects the Computer B hash! Now attacker on Computer A can try to decode the hash, but not only that. He can use Metasploit, taking advantage of the module pass the hash, and own the B machine.
He uses the Administrator hash to connect to ADMIN$ of B and execute some code like reverse shell. The SMB_relay exploit, present in Metasploit, has everything you need to test this Windows vulnerability: it creates a fake sharing folder, captures the hash, pushes a payload and establishes a connection. Of course the pass the hash function can be also used with hashes previously collected:

Are you still secure to connect to a network shared folder? So, if you have to secure a network, remember the users: force a strong domain policy, patch the systems, use SSL wherever you can, set different passwords for different services and, above all, educate the people.

The Password Attacks on Kali Linux [Part 1]

What is the weakest part of the security chain? You know the answer: the one who stand between the keyboard and the desk chair. And what does this user do on her/his first job day? Set a password. Yes, a big part of our security environment lies around that password.

Of course we talk about internal password because Nerwork Administators have well learned the lesson and secure their external accounts with encryption, strong policy, access restriction; in spite of this the internal accounts are the heaven for hackers (and the hell of sysadmins).
Nowadays internal users are, fortunately, low-privileged and some kind of policy forces a little of security, but even if your policy is set with more than 8 characters with numbers, upper and lower case, there will be a user that set as password something like AAAAaaaa1 or Password1.

The complete takeover of a net is a stairway that goes through information gathering, network discovering, password cracking and system owning. Also, finding a low-privilege password is one stair over and it’s actually one of the biggest gap that a penetration tester has to pass. If you find a password, you can quickly test it on other systems and services previously discovered (ssh, ftp, mail): users have the bad routine to use the same keyword for different services.
When you discover a password, you can make an idea about the security company policy and you can try a widespread brute-force attack. If you find, for example, a key of 8 characters, all low case, you can try an attack using this setting on all systems of the LAN. Even if you find a key word from user that isn’t administrator or root there are lot of well-known privilege escalations that can be attempted, especially for old or unpatched system.
Other options that can be used, when you owned a PC with an unprivileged account, are: sniffing traffic,
extracting stored credentials or pivoting other attacks. All these things lead you over and over inthe stairway. In substance, a right association user-password is one of the core success on a pentest and it’s all trusted to an user and his password, that he has chosen on his first job day.

Some terms
Let’s start making a specification. There are two common names you can hear talking about password attack: BruteForce and WordList.
Brute force is when the password is tested using all designated characters, using a set length. The following is an example: use character ‘a’, ‘b’ and set length 2. The password that will be tested are aa, bb, ab and ba; these are 4 tries. You can calculate the amount of attempts: quantity of characters elevated to length used, in this case 2^2=4. Because it is an exponential, it can be become very difficult to test something with ten characters using full ASCII set: according to Password time calculator by lastbit.com this BruteForce attack will take up to 4274902 years.
BruteForce attack, but a WordList one, where what will be used as keys are all single words present in one list.
Note that the password used is exactly the same written in the list. So if in the document there’s the word ‘backup’ only this word will be tested and not ‘Backup’ or ‘back-up’; fortunately there are programs that make these permutations automatically.
So wordlists are often a smarter attempt than a bruteforce attack; in spite of this, during a pen test, you must have a very strong reason to spend hours for this kind of attack.
Of course the following password attacks are done using Kali Linux, because it has every tool you’ll need. Thanks to OffensiveSecurity, Kali Linux, like its father BackTrack, is one of the most used pentesting distributions. If you are reading here you known what we are talking about.

Create your user and password list
To perform a wordlist attack you need, of course, a list of words. There are many techniques to create it, and many places where you can find a precompiled one, but the best way is to create a document based on your needs. From my personal opinion, in this case, is necessary to start from locating valid usernames from the network I‘m testing and using these as a first simple list, trying blank, username as password or very simple passwords.
The harvest, by Edge-Security Research, is a very useful tool that helps you by searching for a company name in various resources database (Google, Linkedin, PGP, Bing…) and then extracts for you probable user names. In the Figure 1 you can see the result of a research: maybe vdiaz, cdelojo and cmartorella are also FTP, SSH or RDP users.
Then you can try to locate some useful accounts from the company website: e-mails and documents such as pdfs, docs or similar can be downloaded to gain such information. You can automate the operation by using another tool by Edge-Security Research: metagoofil (see Figure 2).

Figure 1

Figure 2

Another way to find usernames, when you are in the testing-Company LAN, is to locate a mail server and an SNMP service. Mail server can be vulnerable to VRFY command and you can use it to probe the system for login names. The VRFY is a licit command and fortunately, in modern system, is disabled to patch this security issue, but sometimes you can still use it. Let’s look how it works using a simple Netcat connection:

If the system is vulnerable, smtp-user-enum program can be used to get some usernames; the following is the basic command to use it:

Note that the option -U uses a wordlist in order to find names. If you haven’t one you can find some preloaded in Kali using a command like this:

However the suggestion is to keep your list under 100-150 names. Smtp-user-enum can also be used to test the EXPN function; EXPN is similar to VRFY, but it is used on distribution list and it lists all its users. This can be a bigger problem than the VRFY since sites sometimes have an alias such as “all”.
Another way to compile your focused user list is SNMP analysis. SNMP is a protocol based on UTP that is often used to monitor servers’ service status.
The distribution lists (community strings) are passed in clear and often have the default state (public or private), so you can easily try to find it in order to query the server and get many information.
You can use a combination of Onesixtyone and Snmpcheck; the first can be used to enumerate community strings, so, after locking on the hosts with SNMP service, the program can be run.

The dict.txt is a wordlist (another one) of possible community strings and it is already present in Kali; the host-snmp.txt is a file with the IPs of all hosts with the SNMP service active in the network. The word in the square brackets (see Figure 3) is what you are searching for and the next step is to use this word combined to Snmpcheck to extract data from the service.

Figure 3

In this example the output is limited to the user accounts (grep -a “User accounts” -A 11), but you can get much more info using SNMP such as processes running, programs installed, open ports, network and routing configurations, storages information and much more.

There are several ways to find a username in the net: if something similar to PC-pedro or Maria’s MacBook is found the assumption is that Pedro and Maria are likely to be usernames that will have access on these computers. It’s important to compile the user list meticulously and add every possible username you find, so you can use it later.

Finally you have a user list that will help you in a first simple password attack.
If you will have no results you’ll wish to make some simple extensions to that list using John the Ripper (JtR) or you’ll try another small wordlist like /usr/share/john/password.lst; also in this case JtR can be used to make some little changes.
Let’s see some usage of John the Ripper password cracker by Openwall. Note that this program does more than what you’ll read here. You will see now, how make some simple mutations in order to upgrade your user list and use it as a password list.
The idea is to create something that leads from an input as ‘root’ to an output like Root, ROOT, rootroot, toor, Root1 and so on. Well, let’s expand a small file (wordlist.lst) with only ‘root’ and ‘password’:

In this case a default rule set is used (--rules), but you can modify it using /etc/john/john.conf; note that with 2 words JtR generates 100 words instantly.
The output is normalized, in this case, using tr -s '\n' ' ', but you can remove this part of command and redirect all in a file that fits your needs. Later,
talking about offline attacks, you’ll come across JtR again and you’ll find some other awesome features. Even though, I think, using a huge wordlist is not a good idea, it can be useful to know how to make it, so here are two great tools.
The first is CeWL, you can use it to dig a Company web site to extract words and convert these in a list. The basic usage is very simple and the impact awesome:

You can even use it to extract usernames by pointing CeWL to sites that collect popular birth names. Similarly you can use it to create monothematic wordlists: animals, plants, countries, cars, “Lord of the Rings”, topic words and so on.
The concept I’d like to remark is that in an online password attack you are connected to the LAN: you make network traffic, you stress systems and you can’t stay there all night and day long.
The second tool is Crunch. It can be used to create a word list too, but starts from a different point of view compared with CeWL. Crunch is more like a bruteforce: it generates all words using some parameters you set. Essentially you establish min and max length and a charset (or use the default one); so you can create all possible combinations of characters a, b, c with length from 2 to 4 using the following command:

More specific and interesting usage can be read in the manual page, like the -t option: you can take one word and append some characters to it:

The output can be sent to the screen, to a file, or to another program; this last option allows the use of Chunch directly on an online/offline cracking operation without physically generating a wordlist, saving hard disk space.

Online Password Attack
One of the best tools to complete the online attack is Hydra. This program is tasked to join your lists and to perform the attack over a network service.
The figure 4 explains how it works: it puts together a username list, a password list and a host list split by services to attack (FTP, RDP, SSH, MySQL…).
Then it starts to try every username and password associations on every hosts. Some other parameters can be set such as proxy or the number of tasks; very useful when attacking some cranky service like RDP.

Figure 4

The following is the command that performs a wordlist attack against all FTP hosts in the net:

The -L, -P and -M options are used to point to the wordlists of users, passwords and hosts and can be replaced by -l, -p and a IP to use a single name, password or target. -s is the port to attack and the ftp at the end is the service used as target. -V stands for verbose and -e option tries n null password, s login as pass and/or r reversed login. Finally -t is the number of task that Hydra will use.
The simplest way to learn the use of this tool is to take a look at the GUI xHydra (see Figure 5).

Figure 5

Hydra is the end (maybe happy) of the online password attack, but it is no more than a task executor. Its force lies in the wordlists you will be able to create, don’t forget this.

[end of part 1]

Some scenarios:
– Sniffing traffic
I setup a RAP and start wireshark, ettercap or another network sniffer. Every connections that pass through my PC are intercepted.
– Phishing
I setup a RAP and force it to use mine DNS Server. If someone will connects to me and start to surf I am able to redirect traffic using my DNS. In this case I can implement some kind of phishing.
– Company network back door
I setup, may be using a small RaspberryPi, an access point using the Company network as wired interface. This is an hot spot directly connectet to the Company LAN.
– Caffè-Latte attack
Locoking at the wireless packets you can see the client trying to connect to the previusly registred access point (eg. MY_NETWORK). I Can setup an access point using the same SID the client is searching for. When the client, that is serching for a known SSID, find my RAP named MY_NETKORK it immediatly try to connect. I can use this connection to sniff WPA handshakes or WEP packets and try to decode passwords.
– Extend my connection
I have a notebook connected to a LAN but no access point. I also have a smartphone and I want a wireless connection on-the-fly.

The basic configuration:
– eth0, the wired connection linked to the network
– a DHCP server working on the LAN where eth0 is connected
– wlan0, a wireless interface able to be setted up in monitor mode

I start the monitor mode on wlan0:

This will create the mon0 interface.
Now I setup an AP on mon0, named “MY_network”, channel 11 and WEP autentication. I can also set it as a free wifi without password (airbase-ng --help).

This will create the at0 interface.
Now the AP is started, in another terminal window I make a bridge named rougue-bridge and link at0 to eth0 using the bridge-utils. Note that in Kali Linux the bridge-utils have to be installed (apt-get install bridge-utils) in order to use brctl command.

I can release the IPs of eth0 and at0. This is because the two interfaces are now integrated in the virtual bridge and don’t need an IP anymore:

I need also the IP forwarding:

At the end I configure the test-bridge. Differently from eth0 and ap0 the bridge needs an IP of the LAN where eth0 is connected.

Note that these are temporary operations that will be discarded by rebooting the system.

Extra
Starting an AP to sniffing handshake.

-z sets WPA1 tags (2 = TKIP)
-W set WEP flag in beacons. The option -W 1 is recommended when using -z or -Z
-F where to store the cap file.

Here’s my old simple script to start a Rougue Access Point using Linux Bash. It may need some adjustment, but I think it will work.

Sharpen your axe with BackTrack – Gathering phase [Part 2]

Find your account
As for the hosts, users discovering can be done using many methods. You can scan Google searching for email accounts of your target company, explore corporate Web pages looking at pdf or word documents and who are the creators of this documents; if you have access to the LAN you are testing, you can try to get information from SNMP or SMTP protocol. Below are some scripts and programs that will help you, present in BT.
The harvest, by Edge-Security Research, is a very useful one. It searches for a company name in various resources database (Google, Linkedin, PGP, Bing) and can be used to extract probable username. In Figure 5 you can see the result of a research: maybe vdiaz, cdelojo, cmartorella, and xmendez are also FTP, SSH or RDP users.
Again by Edge-Security.com, you can use metagoofil (/pentest/enumeration/google/metagoofil/) to try to find users that create documents, downloadable from the domain you point at, such as docs or pdfs.

Figure 5

As well as using Web search to catch company users’ names/usernames, you can try to obtain information by SNMP or SMTP.
SNMP is a protocol based on UTP that is often used to monitor server service status. The authentication methods (community strings) are passed in clear and often have the default state (public or private), so you can easily try to find it in order to get many information.
You can use programs such Snmpenum and Onesixtyone for this. Let’s see how they work.
Initially you have to use Onesixtyone to enumerate comunity strings; with the info collected before, make a list of hosts and write it down to a file (/tmp/hosts.txt), then point to pentest/enumeration/snmp/onesixtyone and do the following:

In this command you use a file dict.txt, already present in the onesixtyone folder, to ‘brute force’ the community strings; you use the hosts file you have found before to set targets and, at the end, make a log file.
In Figure 6 you can find a sample of what you can get. In the sample you see some printers, some switches and a server (192.168.1.10).

Figure 6

Go on and use snmpenum over 192.168.1.10 setting ‘public’ as community string, and the windows.txt template (already present) to merge output information (see Figure 7).

Figure 7

This is just a sample, but you can get much more information than these using SNMP. You can find processes running, opened ports, system information and much more.
For now, limit yourself to the users. What you want is to create a document like hosts.txt but with possible user names.
There are many other methods to identify users such as using SMTP server (smtpscan) and try to test the VRFY functionality (smtp-user-enum). Spidering a target website to collect unique words (/pentest/password/cewl) or sniffing network traffic (Wireshark) can also be useful. In the Backtrack > Information Gathering > Network analysis menu you can find many tools to reach your target. Try to find as many names as you can, but do not forget to add to your list the most common user names (root, admin, administrator).

Map the NET
Let’s have a look at network scanners, limiting us to a simple scan, with the only objective to find some services that can be used as a target.
Please, make sure to keep in mind that scanners are much more than what you will read here.
Of course, NC can be used as a network scanner, but the best programs are Unicorscan and Nmap so let’s start with the first one. The commands in Figure 8 perform a simple scan, pointing at a single target (192.168.34.135), testing common TCP (-m T) and UTP (-m U) ports, typically those used by common services such as FTP, SSH, SMB, MySQL. The last command in Figure 8 is a scan of all the subnet 192.168.34.*, but only on FTP, SSH, SMB, and RDP ports.

Figure 8

You can perform the same thing using Nmap. The command nmap 192.168.34.135 scans TCP common port; if you add -sU option it will scan UDP ports. The single target can be replaced with 192.168.34.*, 192.164.34.0/24 or your hosts.txt to explore all subnet or specific IPs; adding the option
-p 21-23,3389 you will limit the scan to port 21, 22, 23 and 3389. The result will be probably the same but if you try Nmap you will see more information. In addition, it can be quickly implemented to determinate what kind of program is listening over the port discovered (-sV) and what operating system is installed (-O). Please, take a look at the Nmap help to learn more options and remember that man command or help are always your friends. If you are afraid to use the Terminal, use the Nmap GUI: Zenmap.
You have to remember that every GUI is at least one layer over its command-line program; anyway let’s use the graphic interface of Nmap and try to find FTP, SSH, Telnet and RDP services in the subnet (Figure 9).
Scanners make a list of hosts using FTP, another one of hosts using RDP, and so on.

Figure 9

Get the Keys
Well done! You have completed your basic network gathering phase, now you can merge all your lists and launch your first attack. What do you need? A username list, a file listing hosts with the specific service, a password list, and a program to put everything together. You don’t have the password list, but one can be easily found in the folder /pentest/password/wordlist/ or by a search on the Web. The kind of attack you will do is called ‘wordlist attack’: it is not the most elegant way to perform a penetration test, but it may be very incisive.
The program you can use to join your lists is Hydra (or its GUI xHydra). Figure 10 explains how it works.
Open the Hydra GUI (Privilege Escalation > Password Attacks > Online Attacks > Hydra-gtk)
and, in the Target tab, insert the target list (e.g.FTP_hosts.txt), the port to test and the protocol (21 / FTP).

Figure 10

The options ‘Show attempts’ and ‘Be verbose’ are useful to better understand what the program does. Go in the Password tab and insert the user and the password lists; don’t forget to check ‘try login as password’ and ‘try empty password’. For a basic test don’t use Tuning and Specific tabs; move to the Start tab and run the attack. It takes a while, but I Hope you can find some user and password association.
You can also try to extend your lists to have more chances, but remember that such attack may take a very long time. In a pen test you must have a very strong reason to spend 8 or more hours for a word list attack.
Anyway, if you find some associations, write them down and be ready to reuse it: users are used to use the same password for more than one service.
You can start to write a file with user:password, you will use it on Hydra in the Password tab instead of users and passwords lists. When you discover a new service, you can first use Hydra with the new file created and then the lists of users and passwords. This will speed up your work.

I hope you now have the user/password to access the FTP, SMB or, if you are lucky, the SSH, or RDP.
This is not the end of the test, this is the beginning. You will use this access to gain more information and to find more vulnerability all over the LAN.
But what about if you can’t find anything? Don’t worry, these are just the first arrows in your quiver. After these, you can try many other things such as web vectors, exploit some vulnerability, or ARP poissoning. There are so many options that the only limit is you and every discovery is the start for the next one.

So when you open a new port, restart from the beginning, restart from sharpenning your axe.

Sharpen your axe with BackTrack – Gathering phase [Part 1]

Abraham Lincoln said ‘Give me six hours to chop down a tree and I will spend the first four sharpening the axe’. This is really the basic concept and the start point of every penetration test.

In a pen test you have to sharpen your axe first by gathering information. The more you obtain, the more surface to attack you will have. The gathering phase isn’t the most exciting one, but surely it is the one that will let you make things better and smarter. So what do you need? Let’s see.
First, you need an adequate system with the right toolkit and a little knowledge of how they work. We will use one of the latest versions of BackTrack (BT) because it is a powerful and widespread operating system, so it will be quite simple to get support or tutorials on the Web: Youtube has a video for almost all the BT tools.
The best way to start with BT is virtualization: you can download its virtual machine ready to be started. In addition, using virtualization, you can easily start a cheap and smart LAB to perform your tests. If you already have a test network, you can also use the bootable CD.

Next you have to be calm and patient, only this way you can collect information and inspect them rightly. You can make your own check-list of tests to do or copy one from the Web, but, when you have your list, you have to follow it meticulously. Remember that you are sharpening.

Now you need to write down all the data you collected in order to have everything recorded so that you can analyze it even when you aren’t connected to the LAN you have to test. Furthermore you will use these records to make a detailed report for your customer or to roll back in case you mess something up.
I use Keepnote to keep track of all my operations and results and Zenmap (Nmap GUI) to map the net, but BT has many more powerful tools than these. Maltego, for example, is awesome.

My friend Netcat
Now let’s start to use the father of all tools, the famous ‘Swiss-army knife for TCP/IP: Netcat‘. Essentially, NC, is a utility which reads and writes data across network connections, using TCP or UDP transport. Nothing more, nothing less.
So why is it so important? When a PC user without experience wants to test if his machine is browsing the Internet, he opens his browser and points to a common address: www.google.com.
This is not the best test he could do, he only finds out if he is browsing, but what about if he is not browsing? So the approach must be different. He has to start from a layer closer to the PC, not closer to the user, and investigate the causes, step by step, up to the human layer.
You are not an inexperienced person, so you start by opening a command shell and pinging your gateway. Is it responding? If not, check it. Then ping an external IP address (e.g. 8.8.8.8 that is the Google DNS). Is it responding? Alright, you are able to go out of your network. Next you test if your DNS is working by pinging a DNS name like www.google.com. Only if all works fine, you open your browser and test the connection. Also, from the browser you can have a problem (e.g. a misconfigured proxy set in the browser) but, after all the tests you have done previously, you can rule out all lower layers and focus on the current one.
That’s why NC is so important. It allow you to start from the lowest layer, it is the equivalent of the ping command used in the example, but it has many more applications.

Well, open your Terminal window and have a look at the NC help.

At the beginning you will use options -l(set NC in listening mode), -v (verbose mode is always better) and -p (set port where NC is listening).Try this:
Open two Terminal windows in the same machine. In the first window start a service that listens
on a specific port using Netcat (it is called the listener).

If you have a look at the network connection of your BT machine, using the command netstat -nat, you will find a listening connection on port 4444 (tcp 0.0.0.0:4444 LISTEN).
In the second window use NC as a client and connect to localhost on port 4444

Hit enter and you establish a simple connection with NC, but what is this?
Essentially, it is a simple chat. If you write something in window 1, it will redirect to windows 2 andvice versa (see Figure 1).

Figure 1

So NC is a program that allows you to communicate using TCP or UDP protocols and you can use it whether as a client or as a server. TCP/UDP connections are more useful than a simple chat: you can use NC to test if a remote port is open, to grab information about a service listening on a remote PC (the banner) and to connect to this service; otherwise you can use it to redirect text, request html page, and, last but not least, remotely admin a PC.
If you have two PCs try to use NC between them or just continue the testing in the same machine (that is the lower layer).
For example, you can try to pass text:

…and if the listener is as the following, you can also
create a file with the text sent:

You can also try the -c option for remote administration.
I suggest you to dig the Internet to search more about Netcat use.

Network hosts identification
As I said, finding information about the target is the base of a successful test. What is the first thing you have to do when you reach a LAN you have to check? Find hosts to use as targets. If you can, create your own hosts individuation scripts using ping and NC or use some of the wonderful tools present in BT. In my opinion, the best are Unicornscan and Nmap, but, since I will shortly explain them later, let’s explore some other programs with less possibility, but working as well.
Start using netdiscover to find live hosts. Using netdiscover -P a network scan is started using common LAN address (the one you are connected to) (see Figure 2).
Netdiscover can be also used on another network interface (-i) and IP range (-r). The -P option is useful for a better output. Netdiscover is a continuing scan tool: it scans over and over the net in order to find new hosts and it could be used to
implement a very simple intrusion detection system. To stop the scan you have to use [CTRL+C].
In a similar way you can use fping with option -g to analyze a range of IPs. Note that fping uses ICMP protocol, whereas netdiscover uses ARP protocol to locate network hosts – this is a good double check.

Figure 2

Don’t forget to write down everything and trace all. Particularly start to compile a list of live hosts. You can also try to give a DNS name to the hosts you find using smbscan, but you will notice that the program can find only a few, those with net bios name enable.
Let’s now try to find something more using DNS discovering. If you are in a domain or if you are scanning for DNS name in the Web, you can try to operate a DNS zone transfer and capture DNS records.
When you can perform this operation, you get other sensible information and, maybe, hosts not previously discovered.
The DNS transfer zone is a query that synchronizes Primary and Secondary DNS servers but if administrators misconfigure them, everyone can query for transfer and get all DNS records. DNSenum is a tool that tries to make a zone transfer and catch the results. The basic operation is quite simple: you just have to set the domain name to target.
Note that you can try the zone transfer both on a local (see Figure 3) or an Internet domain (see Figure 4).
You have to notice that a DNS zone transfer, even if successfully done, does not give hackers a direct access to the servers, but gives them many information that can be useful to expand the attack surface. Look at Figure 4; the DNS transfer zone highlights at least 3 attack vectors: webmail, ftp, sftp.

Figure 3

Figure 4

It is therefore essential to block all the attacks and scans you can. Also ARP and ICMP scans must be stopped in a protected LAN. Unfortunately this isn’t always practicable: in a Microsoft domain, for example, some administrative system tools do not work with restrictive local firewall policies.
It is not easy to find balance between security and efficiency.

You have done a good hosts analysis and you have a list of IPs alive in the network. Now you can start user account identification.

[end of part 1]

You can find other NetCat info in this post

On the local PC I start a logging process:

On the PC to test, maybe using a blind command:

Again on local PC I collect and normalize the log:

I based this Proof of Concept on the article “Blind Command Line Injection” from PenTest Magazine by Mr. Chris Duffy: thank you.