What is Footprinting?

Defining Foot printing

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      Foot printing is the blueprinting of the security profile of an organization, undertaken in a methodological manner.
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      Foot printing is one of the three pre-attack phases. The others are scanning and enumeration.
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      Foot printing results in a unique organization profile with respect to networks (Internet / Intranet / Extra net / Wireless) and systems involved.

      There is no single methodology for foot printing, as a hacker can choose several routes to trace the information. Foot printing therefore, needs to be carried out precisely and in an organized manner. The information unveiled at various network levels can include details of domain name, network blocks, network services and applications, system architecture, intrusion detection systems, specific IP addresses, access control mechanisms and related lists, phone numbers, contact addresses, authentication mechanisms and system enumeration.

      The information gathering activity can be broadly divided into seven phases:

          o The attacker would first unearth initial information (such as domain name),

          o locate the network range of the target system (using tools such as Nslookup, whois etc),

          o  ascertain the active machines (for instance by pinging the machine),

          o discover open ports or access points (using tools such as port scanners),

          o detect operating systems (for instance querying with telnet),

          o uncover services on ports and

          o ultimately map the network.

      This not only speeds up the real attack process, but also aids in helping the attacker prepare better for covering his tracks and thereby leave a smaller or minimal footprint.

      Initial Information:

      Commonly includes:
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            Domain name lookup
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            Locations
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            Contacts (Telephone / mail)

      Information Sources:
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            Open source
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            Who is
          o

            Nslookup

      Hacking Tool:
          o

            Sam Spade

            Open Source Foot printing is the easiest and safest way to go about finding information about a company. Information that is available to the public, such as phone numbers, addresses, etc. Performing whois requests, searching through DNS tables are other forms of open source foot printing. Most of this information is fairly easy to get, and within legal limits. One easy way to check for sensitive information is to check the HTML source code of the website to look for links, comments, Meta tags etc

What is Enumeration ??

Friends, for next few days, I will introduces the enumeration phase of hacking to you. I will try to explain different aspects of enumeration. After this you will be familiar with the following topics:

    * Understanding Windows 2000 enumeration
    * How to Connect via Null Session
    * How to disguise NetBIOS Enumeration
    * Disguise using SNMP enumeration
    * How to steal Windows 2000 DNS information using zone transfers
    * Learn to enumerate users via CIFS/SMB
    * Active Directory enumerations

This is the basis behind stating that while countermeasures the generic approach of hackers towards a system.

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Footprinting - Attack Methods

Attack Methods





The attacker may choose to source the information from:


* A web page (save it offline, e.g. using offline browser such as Teleport pro


* Yahoo or other directories. (Tifny is a comprehensive search tool for USENET newsgroups.


* Multiple search engines (All-in-One, Dogpile), groups.google.com is a great resource for searching large numbers of news group archives without having to use a tool.


* Using advanced search (e.g. AltaVista),


* Search on publicly trade companies (e.g. EDGAR).


* Dumpster diving (To retrieve documents that have been carelessly disposed)


* Physical access (False ID, temporary/contract employees, unauthorized access etc)

There are four RIRs, each maintaining a whois database holding details of IP address registrations in their regions. The RIR whois databases are located at:
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ARIN (North America and sub-Saharan Africa)
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APNIC (Asia Pacific region)
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LACNIC (Southern and Central America and Caribbean)
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RIPE NCC (Europe and northern Africa)
Tools
There are tools available to aid a whois lookup. Some of them are Sam Spade (downloadable from www.samspade.org). Smart Whois (downloadable from www.tamos.com). Netscan (downloadable from www.netscantools.com) and GTWhois (Windows XP compatible) (www.geektools.com) etc.

What is Enumeration (PART 2)???

#If acquisition and non intrusive probing have not turned up any results, then an attacker will next turn to identifying valid user accounts or poorly protected resource shares.
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Enumeration involves active connections to systems and directed queries.
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The type of information enumerated by intruders:

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      Network resources and shares
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      Users and groups
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      Applications and banners

      The objective of the attacker will be to identify valid user accounts or groups where he can remain inconspicuous once he has compromised the system. Enumeration involves active connections being made to the target system, or subjecting it to directed queries made to a system. Normally, an alert and secure system will log such attempts. Often the information gathered is what the target might have made public - such as a DNS address. However, it is possible that the attacker stumbles upon a remote IPC share such as the IPC$ in windows, that can be probed with a null session and shares and accounts enumerated.
          Concept     

      On ascertaining the security posture of the target, the attacker can turn this information to this advantage by exploiting some resource sharing protocol or compromising an account. The type of information enumerated by hackers can be loosely grouped into the following categories:
         1.

            Network resources and shares
         2.

            Users and Groups
         3.

            Applications and Banners


            ---

Net Bios Null Sessions

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  The null session is often refereed to as the Holy Grail of Windows hacking. Null Sessions take advantage of flaws in the CIFS/SMB (Common Internet File System/ Server Messaging Block).
  
  
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  You can establish a Null Session with a Windows (NT/2000/XP) host by logging on with a null user name and password.
  
  
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  Using these null connections allows you to gather the following information from the host:
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    List of users and groups
    
    
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    List of machines
    
    
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    List of shares
    
    
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    Users and host SIDs (Security Identifiers)
    In the enumeration phase, the attacker gathers information such as network user and group names, routing tables, and Simple Network Management Protocol (SNMP) data
    
    However, in addition to the standard user, the OS also supports a unique type of user called the 'null' user, which is basically a pseudo-account that has no username or password, but is allowed to access certain information on the network.
    
    
    
    The Null user is capable of enumerating account names and shares on domain controllers, member servers, and workstations. This makes the Null user, a user with no credentials, a potential means of attack by crackers to elicit information and compromise the system.
    Let us take a look at a typical LANMAN sessions on Windows NT 4.0
    
    
    
  
  

Remote machines establish a session with the Windows NT server using a challenge response protocol. The security of the information channel is ensured through a sequence of communications as outlined below.

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  The remote machine (or session requestor / client) sends a request to the session server (or session acceptor). This may be within the same domain or across domains.
  
  
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  The session server responds by sending across a random 64-bit challenge question to the client. The client responds to the question with a 24-bit answer which is hashed with the password of the user account that is requesting the session.
  
  
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  The session server accepts the response and verifies with the local security authority regarding the authentication of the user account and password.
  
  
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  The LSA confirms the identity of the requestor by verifying that the response was hashed with the correct password for the user that the requestor purports to be. This confirmation occurs locally if the requestor's account is a local account on the server. However, if the requestor's account is a domain account, the response is forwarded to the concerned domain controller for authentication.
  
  
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  On authenticating the response, an access token is generated by the session server and sent across to the client.
  
  
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  The client then uses this access token to connect to resources on the server till the newly established session is terminated.
  
  
  Windows 2000 provides three groups whose membership is controlled by the administrator: Users, Power Users, and Administrators. The group whose membership is controlled by the operating system or domain is Authenticated Users. It is the same as the Everyone group, except that it does not contain anonymous users or guests. Unlike the Everyone group in Windows NT 4.0, the Authenticated Users group is not used to assign permissions. Only groups controlled by the administrator, primarily Users, Power Users, and members of the Administrators group, are used to assign permissions.
  
  
  
  
  

Now, let us take a look at a typical LANMAN sessions on Windows 2000

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  Here, the client sends a pre-authenticated (hash of user password) request along with a time stamp to the key distribution center (KDC) that resides on the domain controller (DC) of the concerned domain, requesting for a ticket granting ticket (TGT).
  
  
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  The KDC extracts the hash of the user identity from its database and decrypts the request with it, noting the time stamp as well for recentness of request. A valid user account results in successful decryption.
  
  
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  The KDC sends back a TGT, that contains among other information the session key (encrypted with users password) and the security identifiers (SID) identifying the user and the group among other things.
  
  
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  The client uses the ticket to access the required resources.
  
  

  A null session is an insecure (unauthenticated) connection with no proof of identity. No user and password credentials are supplied in the establishment of the session. No session key is exchanged when establishing a null session, and hence it is impossible for the system to send encrypted or even signed messages on behalf of the user under a null session.

  When the LSA is asked to create a token for a remote client communicating via a null session, it produces a token with a user SID of S-1-5-7 (the null logon session), and a user name of anonymous logon. We have seen earlier that Everyone is included in all tokens, and the null session is classified as a network logon. This gives the null user access to file system shares and named pipes.
  
  
  Other areas where null sessions are considered useful is when the LMHOSTS.SAM file uses the "#INCLUDE " tag. The share point that contains the included file must be setup as a null session share. Additionally where a service, running under the local "SYSTEM" account, needs access to some network resource, a null session may be established to access these resources.
  
  
  An interesting part is that Null sessions can also be established at the API level with languages such as C++. Null sessions can be used to establish connections to 'null session pipes', if it is allowed by the server. A 'pipe' is a facility that allows a process on one system to communicate with a process on another system, while a inter process communication share allows communication between two processes on the same system.
  
  
  Null sessions can also be used to establish connections to shares, including such system shares as \\servername\IPC$. The IPC$ is a special hidden share. It may be noted that the IPC$ share is an interface to the 'server' process on the machine, also associated with a pipe so it can be accessed remotely. Null sessions make the enumeration of users, machines, and resources easier for administrative purposes especially across domains. This is the lure for the attacker who intends to use a null session to connect to the machine.
  
  
  During port scanning, the attacker takes note of any response from TCP port 139 and 445. Why would these ports interest an attacker? The answer lies in the SMB protocol.
  The SMB (Server Message Block) protocol is known for its use in file sharing on Windows NT / 2000 series among other things. Attackers can potentially intercept and modify unsigned SMB packets then modify the traffic and forward it so that the server might perform undesirable actions. Alternatively, the attacker could pose as the server or client after a legitimate authentication and gain unauthorized access to data.
  
  
  SMB is the resource sharing protocol supported by many Microsoft operating systems; it is the basis of network basic input/output system (NetBIOS) and many other protocols. SMB signing authenticates both the user and the server hosting the data. In Windows NT it ran on top of NBT (NetBIOS over TCP/IP), making it a bulky protocol with a large header as well as consuming greater time. In Windows NT, it used the ports 137, 138 (UDP) and 139 (TCP). In Windows 2000, SMB was allowed to directly run over TCP/IP, without the extra layer of NBT. Therefore, port 445 started being used for this purpose.
  
  
  Each SMB session consumes server resources. Establishing numerous null sessions will slow or possibly crash the server even in Windows 2003. An attacker could repeatedly establish SMB sessions until the server stops responding. SMB services will become slow or unresponsive.

NetBIOS connection - So What's the Big Deal?

• Anyone with a NetBIO S connection to your computer can easily get a full dump of all your usernames, groups, shares, permissions, policies, services and more using the Null user.
  
  
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  The above syntax connects to the hidden Inter Process Communication 'share' (I PC $) at IP address 192.34.34.2 with the built- in anonymous user (/u:"") with ("") null password.
  
  
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  The attacker now has a channel overwhich to attempt various techniques.
  
  
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  The CIFS/SMB and NetBIOS standards in Windows 2000 include API s that return rich information about a machine via TCP port 139 - even to unauthenticated users.
  
  
  C: \>net use \\192.168.104.81 \IPC$ "" /u: ""
  The enumeration of machines and resources in a domain also makes it easier for an attacker to break in. If he is able to anonymously obtain the names of all of the machines in a domain, and then list the resource shares on those machines, it is only a matter of time before he finds a share which is open to "Everyone". Other possibilities include password cracking for a username that was enumerated, planting a backdoor for later access, dumping sensitive information etc.
  Let us see how a null session is established and how a remote computer can be enumerated from the command line prompt of a windows machine. In the example shown below, we can see that establishing a null session on the target host reveals that the system root can be easily compromised as the default setting of 'Everyone' may not have been changed, and the shares are visible to all.
  
  
  
  

In a NULL session, the TCP/IP connection to port 139 is made first with the following: net use \\127.0.0.1.i\ipc$ "" /user:"". This is followed by using the session layer protocols SMB and NetBIOS to access the hidden remote IPC share IPC$. The IPC$ is a special hidden share which allows communication between two processes on the same system (Inter Process Communication). The IPC$ share is an interface to the 'server' process on the machine. It is also associated with a pipe so it can be accessed remotely. This technique was programmatically written into an old exploit called the Red Button attack. This was addressed and fixed by Microsoft in Service Pack 3 for NT 4.0.

Once the attacker has a list of the remote shares, he could then attempt to map to a remote share. An example of the command structure for the attack is shown in the screenshot above. This attack will only work if the share is not password protected or shared out to the 'everyone' group.

Access to the hard drive is a serious security breach. Even if the attacker does not map a drive, he can gather sensitive information such user accounts, password policy and similar data that he can exploit later to continue his attack on the system. This may not be apparent to the victim initially, and the attacker can take the advantage of the time lapse for more information gathering and planting malicious code such as a virus or a Trojan. The open file share attack generally makes Trojan planting extremely easy to do. For instance, an intruder might try to place a key logger batch into the start-up folder to collect further information and perhaps log on later as an authenticated users.

NetBIOS connection - So What's the Big Deal?

• Anyone with a NetBIO S connection to your computer can easily get a full dump of all your usernames, groups, shares, permissions, policies, services and more using the Null user.
  
  
• 
  
  
  The above syntax connects to the hidden Inter Process Communication 'share' (I PC $) at IP address 192.34.34.2 with the built- in anonymous user (/u:"") with ("") null password.
  
  
• 
  
  
  The attacker now has a channel overwhich to attempt various techniques.
  
  
• 
  
  
  The CIFS/SMB and NetBIOS standards in Windows 2000 include API s that return rich information about a machine via TCP port 139 - even to unauthenticated users.
  
  
  C: \>net use \\192.168.104.81 \IPC$ "" /u: ""
  The enumeration of machines and resources in a domain also makes it easier for an attacker to break in. If he is able to anonymously obtain the names of all of the machines in a domain, and then list the resource shares on those machines, it is only a matter of time before he finds a share which is open to "Everyone". Other possibilities include password cracking for a username that was enumerated, planting a backdoor for later access, dumping sensitive information etc.
  Let us see how a null session is established and how a remote computer can be enumerated from the command line prompt of a windows machine. In the example shown below, we can see that establishing a null session on the target host reveals that the system root can be easily compromised as the default setting of 'Everyone' may not have been changed, and the shares are visible to all.
  
  
  
  

In a NULL session, the TCP/IP connection to port 139 is made first with the following: net use \\127.0.0.1.i\ipc$ "" /user:"". This is followed by using the session layer protocols SMB and NetBIOS to access the hidden remote IPC share IPC$. The IPC$ is a special hidden share which allows communication between two processes on the same system (Inter Process Communication). The IPC$ share is an interface to the 'server' process on the machine. It is also associated with a pipe so it can be accessed remotely. This technique was programmatically written into an old exploit called the Red Button attack. This was addressed and fixed by Microsoft in Service Pack 3 for NT 4.0.

Once the attacker has a list of the remote shares, he could then attempt to map to a remote share. An example of the command structure for the attack is shown in the screenshot above. This attack will only work if the share is not password protected or shared out to the 'everyone' group.

Access to the hard drive is a serious security breach. Even if the attacker does not map a drive, he can gather sensitive information such user accounts, password policy and similar data that he can exploit later to continue his attack on the system. This may not be apparent to the victim initially, and the attacker can take the advantage of the time lapse for more information gathering and planting malicious code such as a virus or a Trojan. The open file share attack generally makes Trojan planting extremely easy to do. For instance, an intruder might try to place a key logger batch into the start-up folder to collect further information and perhaps log on later as an authenticated users.