Good morning friends. In the previous part of the tutorial, we performed a vulnerability scan on our target Metasploitable and got some high ranking vulnerabilities. Although little bit boring, it can be very helpful for the success of the hack in real time. In our previous parts, we have performed scanning and banner grabbing. So we already know what services are running on the target machine. We can perform enumeration on all these services. It also provides an authenticated inter-process communication mechanism.
To know more about SMB please go here. SMB enumeration can provide a treasure trove of information about our target. The first tool we will use is enum4linux. As the name suggests, it is a tool used for enumeration of Linux. Using this tool, first let us see the users of the SMB service.
As we can see above, this system is part of a workgroup. Know the difference between domain and workgroup. We can see below that it has listed all the SMB users present on the target. Of all the usernames the tool got us, I am assuming only three usernames are useful to us: user,root and msfadmin since others seem more like processes but we will keep our fingers crossed. Before we check for validity of these credentials, let us perform a full enumeration with enum4linux.
As you can see below, it lists us Nbtstat information of what services are active on the target. Ok, now we know the users. We will use a tool called acccheck for this purpose.
We will see more about password cracking later. So I specify a dictionary which consists of most common passwords used. Here, I am just guessing that the user may be using a common password. After specifying all the options, Hit Enter. The cracking process starts as shown below. Once the tool gets the correct password, it stops the scan and displays a success message as shown below.
Seeing this result, I get a new idea. There might be a possibility that all the users may be using their username as password. To find out this, I create a new file called user.
For this, we will use another tool called SMBMap. SMBMap allows users to enumerate samba share drives across an entire domain. Since we have READ privileges, let us read the drive on the target system as shown below. Your email address will not be published.
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Of all the common protocols a new analyst encounters, perhaps none is quite as impenetrable as Server Message Block SMB. Its enormous size, sparse documentation, and wide variety of uses can make it one of the most intimidating protocols for junior analysts to learn. But SMB is vitally important: lateral movement in Windows Active Directory environments can be the difference between a minor and a catastrophic breach, and almost all publicly available techniques for this movement involve SMB in some way.
While there are numerous guides to certain aspects of SMB available, I found a dearth of material that was accessible, thorough, and targeted towards network analysis. The goal of this guide is to explain this confusing protocol in a way that helps new analysts immediately start threat hunting with it in their networks, ignoring the irrelevant minutiae that seem to form the core of most SMB primers and focusing instead on the kinds of threats an analyst is most likely to see.
This guide necessarily sacrifices completeness for accessibility: further in-depth reading is provided in footnotes. There are numerous simplifications throughout to make the basic operation of the protocol more clear; the fact that they are simplifications will not always be highlighted.
Lastly, since this guide is an attempt to explain the SMB protocol from a network perspective, the discussion of host based information windows logs, for example has been omitted. At its most basic, SMB is a protocol to allow devices to perform a number of functions on each other over a usually local network.
SMB has been around for so long and maintains so much backwards compatibility that it contains an almost absurd amount of vestigial functionality, but its modern core use is simpler than it seems.
For the most part, today SMB is used to map network drives, send data to printers, read and write remote files, perform remote administration, and access services on remote machines. In this case, the machine If you open this PCAP in wireshark and look at the packet details, you will find a lot of information, and it can sometimes be difficult to tell what is relevant. Fortunately, as analysts we are mostly unconcerned with the details of these setup packets with the exception of those relevant to authentication, which is discussed below.
For the most part it is sufficient to make note of the machine and share being accessed and move on. It does not map to the file system directly, instead providing an interface through which remote procedure calls RPC can be performed, as discussed below. It looks like this : .
Next We append some metadata including timestamps to the complete remote file 5 and close it. Our file transfer is now complete. Reads work similarly; the following PCAP shows the write operation exactly reversed.
Tutorial: Reconnaissance alerts
Host We use GetInfo to get a number of pieces of metadata from the file 2and then make read requests for the actual file bytes 3. These simply allow two commands to be packaged as one, with one SMB header. For most purposes, you can treat them as two separate commands. An unusual login on a device can be a thread that unravels an entire lateral movement attempt. NTLM, the older of the two, has been in use since the release of Windows NT in but remains supported in the latest versions of Windows.
It is thus extremely vulnerable to pass-the-hash type attacks,  and Kerberos is the recommended authentication protocol for Active Directory environments. NTLM continues to be used in Workgroup environments Windows environments without domain controllers and some older systems.
A full explanation of Kerberos is beyond the scope of this paper,  so we will instead focus on the two aspects of the protocol that are important for our discussion here. One, Kerberos authentication happens separately from SMB, and involves interaction with a TGS and the service you are attempting to authenticate to.
Two, Kerberos tickets, used to access services on remote machines, do not contain user information that is useful to us in cleartext. Pass-the-hash attacks on NTLM and pass-the-ticket attacks on Kerberos  can both be very difficult to detect at a network level, since the traffic often looks the same as legitimate use.
It is key for network defenders to have an understanding of what users should be logged into which machines, as well as to maintain good discipline about which accounts are used to access which resources.This issue has been around since at least but has proven either difficult to detect, difficult to resolve or prone to being overlooked entirely.
The primary failure of VA in finding this vulnerability is related to setting the proper scope and frequency of network scans. It is vital that the broadest range of hosts active IPs possible are scanned and that scanning is done frequently. We recommend weekly. Your existing scanning solution or set of test tools should make this not just possible, but easy and affordable. If that is not the case, please consider AVDS. Penetration Testing pentest for this Vulnerability The Vulnerabilities in SMB Shares Enumeration is prone to false positive reports by most vulnerability assessment solutions.
AVDS is alone in using behavior based testing that eliminates this issue. For all other VA tools security consultants will recommend confirmation by direct observation. In any case Penetration testing procedures for discovery of Vulnerabilities in SMB Shares Enumeration produces the highest discovery accuracy rate, but the infrequency of this expensive form of testing degrades its value. The ideal would be to have pentesting accuracy and the frequency and scope possibilities of VA solutions, and this is accomplished only by AVDS.
Hackers are also aware that this is a frequently found vulnerability and so its discovery and repair is that much more important.Basics of Hacking - Enumeration
If your current set of tools is indicating that it is present but you think it is probably a false positive, please contact us for a demonstration of AVDS. There was an industry wide race to find the most vulnerabilities, including Vulnerabilities in SMB Shares Enumeration ,and this resulted in benefit to poorly written tests that beef up scan reports by adding a high percentage of uncertainty. This may have sold a lot of systems some years ago, but it also stuck almost all VA solutions with deliberately inaccurate reporting that adds time to repairs that no administrator can afford.
Beyond Security did not participate in this race to mutually assured destruction of the industry and to this day produces the most accurate and actionable reports available. Vulnerabilities in SMB Shares Enumeration is a Medium risk vulnerability that is also high frequency and high visibility. This is the most severe combination of security factors that exists and it is extremely important to find it on your network and fix it as soon as possible.
Home Solutions. This feature is active only when viewing files and folders in a shared folder; it is not active when viewing files and folders in the local file system. Impact: Attackers can access those shares remotely.
Request Info.The options allow the name queries to be directed at a particular IP broadcast area or to a particular machine. All queries are done over UDP. As you can observe it has dumped almost the same result as above, but the most important fact is that it enumerates the whole subnet. SMBMap allows users to enumerate samba share drives across an entire domain.
Finding and Fixing Vulnerabilities in SMB Shares Enumeration , a Medium Risk Vulnerability
This tool was designed with pen testing in mind and is intended to simplify searching for potentially sensitive data across large networks. As you can observe, this tool not only shows share files even show their permission.
It offers an interface similar to that of the FTP program. Operations include things like getting files from the server to the local machine, putting files from the local machine to the server, retrieving directory information from the server and so on. Moreover, we can use smbclient for sharing the file in the network. Here you can observe we had login successfully using anonymous login and transferred the user.
It has undergone several stages of development and stability. Further, we had use enumerate user command, and you can see the usernames as well as their RID the suffix of their SID in hexadecimal form. We have to use the queryuser command to catch-all kinds of information related to an individual user based uniquely on the users RID in hex form, here RID: 0x3e8 denotes root user account. Here note that the output result shows the last logon time for the user root, as well as the Password last set Time.
Such kind of things is very valuable for penetration testers. And, this all can be achieved without an admin username and password. Following Script attempts to detect if a Microsoft SMBv1 server is vulnerable to a remote code execution vulnerability ms, a. The vulnerability is actively exploited by WannaCry and Petya ransomware and other malware.
Additionally, it checks for known error codes returned by patched systems. From the given below image you can observe, it found the target machine is vulnerable to ms due to SMBv1.
Enum4linux is a tool for enumerating information from Windows and Samba systems. It attempts to offer similar functionality to enum. It is written in Perl and is basically a wrapper around the Samba tools smbclient, rpclient, net, and nmblookup. As you can observe, it has shown target belongs to Workgroup and dump NetBIOS name along with their suffix and much more information. Also, perform enumerate user along with their RID in hexadecimal form with the help of rpcclient.
Hence enum4linux is Swiss-knife when it comes to performing enumeration. But it cannot identify SMB vulnerability like Nmap. Hi, very good article lots of info for me. My teacher says enum4linux is funny.
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Like this: Like Loading Leave a Reply Cancel reply Your email address will not be published.Once a user is connected to the a share through a null session they can enumerate information about the system and environment.
Easy to use tools are freely available that can automate the enumeration and gathering of this data, providing an attacker with a wealth of information that may aid in an internal attack. For example, the enumeration of identified user accounts in combination with details of the password policy in use, provides an attacker with the ability to conduct specific targeted password guessing attacks. Setting the value to 1 allows anonymous access but will deny enumeration of user accounts and admin shares.
Once the value has been changed, verify the changes a have taken affect by rebooting the devices and attempting to initiate a null session. Note: Disabling anonymous access could have a negative impact on functionality that relies on it. The business landscape has undergone a sudden, drastic shift to remote access, in order to cope with the current social isolation requirements. The team here at 7 Elements are proud to be a supporter of the Scottish Business Hub.
The hub, created by ScotlandIS with support across industry, … Read more Follow: Twitter Linked In. Information that can be gained includes but not limited to : Users and groups Operating system information Password policies Privileges Available shares Easy to use tools are freely available that can automate the enumeration and gathering of this data, providing an attacker with a wealth of information that may aid in an internal attack. Blog Zooming in on security The business landscape has undergone a sudden, drastic shift to remote access, in order to cope with the current social isolation requirements.Attempts to enumerate the users on a remote Windows system, with as much information as possible, through two different techniques both over MSRPC, which uses port or ; see smb.
The goal of this script is to discover all user accounts that exist on a remote system. This can be helpful for administration, by seeing who has an account on a server, or for penetration testing or network footprinting, by determining which accounts exist on a system.
A penetration tester who is examining servers may wish to determine the purpose of a server. By getting a list of who has access to it, the tester might get a better idea if financial people have accounts, it probably relates to financial information.
Additionally, knowing which accounts exist on a system or on multiple systems allows the pen-tester to build a dictionary of possible usernames for bruteforces, such as a SMB bruteforce or a Telnet bruteforce. These accounts may be helpful for other purposes, such as using the accounts in Web applications on this or other servers.
From a pen-testers perspective, retrieving the list of users on any given server creates endless possibilities. By default, both are used, but they have specific advantages and disadvantages. Using both is a great default, but in certain circumstances it may be best to give preference to one.
More information is returned more than just the username. Every account will be found, since they're being enumerated with a function that's designed to enumerate users.
Advantages of using LSA bruteforcing: More accounts are returned system accounts, groups, and aliases are returned, not just users. Requires a lower-level account to run on Windows XP and higher a 'guest' account can be used, whereas SAMR enumeration requires a 'user' account; especially useful when only guest access is allowed, or when an account has a blank password which effectively gives it guest access.
If this succeeds, it will return a detailed list of users, along with descriptions, types, and full names. This can be done anonymously against Windowsand with a user-level account on other Windows versions but not with a guest-level account. EnumDomains : get a list of the domains. QueryDomain : get the sid for the domain. OpenDomain : get a handle for each domain. QueryDisplayInfo : get the list of users in the domain.
Close : Close the domain handle. Close : Close the connect handle. The advantage of this technique is that a lot of details are returned, including the full name and description; the disadvantage is that it requires a user-level account on every system except for Windows Additionally, it only pulls actual user accounts, not groups or aliases. Regardless of whether this succeeds, a second technique is used to pull user accounts, called LSA bruteforcing.
LSA bruteforcing can be done anonymously against Windowsand requires a guest account or better on other systems. It has the advantage of running with less permission, and will also find more account types i.
The disadvantages is that it returns less information, and that, because it's a brute-force guess, it's possible to miss accounts. It's also extremely noisy.GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together. This feature exists to allow unauthenticated machines to obtain browse lists from other Microsoft servers. A null session also allows unauthenticated hackers to obtain large amounts of information about the machine, such as password policies, usernames, group names, machine names, user and host SIDs.
The solution to this is to disable Netbios from broadcasting. The setting for this is in, what i hope, a very familiar place thaet you might not have really paid attention too before.
One of the unexpected consequences of disabling Netbios completely on your network is how this affects trusts between forests. Windows let you create an external non-transitive trust between a domain in one forest and a domain in a different forest so users in one forest could access resources in the trusting domain of the other forest.
Windows Server takes this a step further by allowing you to create a new type of two-way transitive trusts called forest trusts that allow users in any domain of one forest access resources in any domain of the other forest.
An Introduction to SMB for Network Security Analysts
But Windows is pretty old, since as of writing we are generally on Windows now. So if you would like to disable Netbios on your servers yet will be effected by the side effect for Forest trusts then ideally you should upgrade and keep up with the times anyway.
See below for step by step instructions on disabling Netbios on workstations:. Under Tasks, click Manage network connections. Under Network and Internet, click View network status and tasks. Click Change adapter settings. Right-click Local Area Connection, and then click Properties. Skip to content. Permalink Dismiss Join GitHub today GitHub is home to over 40 million developers working together to host and review code, manage projects, and build software together.
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