Extracting Kerberos Credentials from PCAP

NetworkMiner is one of the best tools around for extracting credentials, such as usernames and passwords, from PCAP files. The credential extraction feature is primarily designed for defenders, in order to analyze credential theft and lateral movement by adversaries inside your networks. But the credential extraction feature is also popular among penetration testers. In this blog post I will demo how Kerberos hashes can be extracted from captured network traffic with NetworkMiner, and how these hashes can be cracked in order to retrieve the clear text passwords.

Installing NetworkMiner in Kali Linux

I’m using a clean install of Kali Linux 2019.3, on which I have installed NetworkMiner by following the step-by-step instructions in our guide for installing NetworkMiner in Ubuntu, Fedora and Arch Linux.

Extracting Kerberos Hashes from PCAP

There is a capture file in Wireshark’s sample captures called krb-816.cap. This capture file contains Kerberos traffic from a Windows XP machine, as two user accounts perform a domain logon. Let’s download that PCAP file and open it in NetworkMiner.

The “Credentials” tab contains the extracted Kerberos hashes. Right-click on the first $krb5pa$23$ hash and select “Copy Password” to put the password into the system clipboard.

Paste the password to a text file, either using a text editor or directly from a shell.

Note: You'll need to do press Ctrl+Shift+Insert in GNOME Terminal to paste from the system clipboard, which is where NetworkMiner has put the password.

You can now try to crack the hash, for example by running John the Ripper (JtR) or hashcat.

Yay! We now know that the password of user “des” was “123”. Let’s try to recover the password of the user “u5” as well, but this time we’ll use the $krb5asrep$23$ hash.

Apparently the password for user u5 was “123” as well.

If you wanna replace JtR with hashcat, then make sure to use the following hash modes:

• $krb5pa$23$: hashcat -m 7500
• $krb5tgs$23$: hashcat -m 13100
• $krb5asrep$23$: hashcat -m 18200

Running the Command Line version of NetworkMiner

The commercial version of NetworkMiner comes with a command line tool called NetworkMinerCLI. You can extract the Kerberos hashes from a PCAP file and save them to a CSV file using NetworkMinerCLI like this:

NetworkMinerCLI has now created a set of CSV files, one for each type/class of information found in the capture file. In this case we want the krb-816.cap.Credentials.csv file, in which the hashes and passwords are in column 5:

Posted by Erik Hjelmvik on Thursday, 14 November 2019 12:25:00 (UTC/GMT)

Tags: #PCAP​ #Kerberos​ #Linux​ #hashcat​ #John​ #JtR​ #NetworkMinerCLI​

NetworkMiner 2.5 Released

I am happy to announce the release of NetworkMiner 2.5 today! This new version includes new features like JA3 and parsers for the HTTP/2 and DoH protocols. We have also added support for a few older protocols that are still widely used, such as Kerberos and the CIFS browser protocol. Additionally, NetworkMiner can now parse PCAP files up to twice as fast as before!

Improving Passive TLS Analysis with JA3

Almost all web traffic is TLS encrypted nowadays, which prevents incident responders, analysts and investigators from inspecting otherwise unencrypted HTTP traffic for clues about malicious behavior or criminal intent. This requires analysts to use alternative approaches, such as looking at hostnames and X.509 certificates. This type of analysis is supported by NetworkMiner, since it parses Server Name Indication fields in client TLS handshakes and extracts X.509 certificates automatically when PCAP files are loaded.

In this release we’ve also added support for another passive TLS analysis technique called JA3, which is a method for fingerprinting TLS client implementations.

NetworkMiner leverages the JA3 fingerprint database from Trisul Network Analytics in order to match observed JA3 hashes to hashes of known malware and “normal” applications. This is what it looks like when the capture file “snort.log.1428364808”, from the FIRST 2015 “Hands-on Network Forensics” training (available here), has been loaded into NetworkMiner 2.5:

Image: JA3 fingerprint of a Skype client in NetworkMiner 2.5

The JA3 hash is also available in the “Parameters” tab, which is useful in order to find out what hosts that particular TLS implementation was reaching out to.

Image: Filtering on JA3 hash 06207a1730b5deeb207b0556e102ded2

HTTP/2 and DoH Support

Passive analysis of TLS traffic, such as HTTPS, often doesn’t give sufficient visibility. Many organizations therefore use TLS proxies in order to decrypt the traffic going in and out from their networks. However, more than half of all HTTPS traffic is actually http2 (RFC 7540) nowadays. This has previously been an issue for users who wanted to analyze decrypted http2 traffic from their TLS intercepting proxies with NetworkMiner. We’re happy to announce that NetworkMiner now can parse http2 traffic, that has been decrypted by a TLS proxy, and extract files from the http2 transfers.

NetworkMiner 2.5 also supports the DNS over HTTPS (DoH) protocol (RFC 8484), which is a technique for sending DNS queries as http2 POST requests and parsing the returned data as DNS responses. We’ve incorporated the DoH data into NetworkMiner’s DNS tab, so that you can analyze it just like normal DNS traffic.

Image: DoH traffic to mozilla.cloudflare-dns.com in NetworkMiner’s DNS tab

Please note that NetworkMiner 2.5 does not perform TLS decryption. This means that NetworkMiner can only parse the contents of a TLS stream if it has been decrypted by a TLS proxy, such as PolarProxy.

Extracting Kerberos Hashes from PCAP

NetworkMiner’s support for the Kerberos protocol allows you to passively track which user accounts that are authenticating to what services, simply by monitoring network traffic. This is a feature is essential in order to track credential theft and lateral movement by adversaries inside your networks. After implementing kerberos username and hash extraction we realized that this feature could also be valuable for penetration testers. We therefore decided to present extracted Kerberos credentials in a format that is compatible with tools like hashcat and John the Ripper.

Image: Kerberos krb5pa, krb5asrep and krb5tgs credentials extracted from the Wireshark sample capture file Krb-contrained-delegation.cap

For more information about Kerberos hashes, please see our Extracting Kerberos Credentials from PCAP blog post.

Even more NetBIOS and CIFS Artifacts!

NetworkMiner is a popular tool for extracting files transferred over SMB and SMB2 from capture files. It can also extract a great deal of information about the communicating hosts from protocols like NetBIOS and SMB/CIFS, but earlier this year Chris Raiter notified us about an important piece of information that was missing in NetworkMiner: NetBIOS Name Service (NBNS) lookups and responses!

A couple of months later Dan Gunter sent us another great feature request for another protocol that runs on top of NetBIOS: the CIFS Browser Protocol (aka MS-BRWS).

We’re happy to announce that NBNS queries and responses are now shown in NetworkMiner’s Parameters tab, and details like hostnames, domain names, Windows versions and uptime us extracted from the MS-BRWS protocol. See the screenshots below, which were created by loading the capture file “case09.pcap” from Richard Bejtlich’s TCP/IP Weapons School 2.0 Sample Lab into NetworkMiner 2.5. Thanks for sharing Richard!

Image: Hostname, domain and Windows version extracted from MS-BRWS traffic

Image: NBNS queries and responses in NetworkMiner’s Parameters tab

Mono 5 Required for Linux and MacOS

Linux and MacOS users, who run NetworkMiner with help of Mono, will need to ensure they have Mono 5 (or later) installed in order to run NetworkMiner 2.5. We recommend using at least Mono 5.18.

Instructions for installing NetworkMiner on Linux can be found in our blog post ”HowTo install NetworkMiner in Ubuntu Fedora and Arch Linux”.

MacOS users can refer to our “Running NetworkMiner on Mac OS X” blog post.

Users who are unable to install Mono 5 are recommended to use the old NetworkMiner 2.4 release, which can be downloaded here:
https://www.netresec.com/?download=NetworkMiner_2-4

NetworkMiner Professional

Apart from the features mentioned so far, our commercial tool NetworkMiner Professional now comes with a few additional new features. One of these features is port independent identification of RDP traffic, so that mstshash credentials can be extracted from RDP sessions even if the service doesn’t run on port 3389. The OSINT lookup context menus in NetworkMiner Professional have also been enriched with the following online services:

• ja3er.com JA3 lookup
• abuse.ch JA3 lookup
• urlscan.io URL, DNS and IP lookup
• IPAddress.com IP lookup
• OpenDNS DNS lookup
• circl.lu IP/BGP lookup (thank you Raphaël)
• GreyNoise Visualizer IP lookup
• RIPEstat IP lookup

Several new features have also been included in the command line tool NetworkMinerCLI, including:

• Recursive loading of PCAP files with the "-R” switch.
• Configurable export types (hosts, files, DNS etc) with the “-x” switch.
• Relative paths in CSV, XML and JSON/CASE exports unless the “-- absolutePaths” switch is used.

Credits

I’d like to thank Dan Gunter, Chris Raiter, Chris Sistrunk and a few more (who I cannot mention here) for contributing with feature requests and bug reports that have helped improve NetworkMiner.

Upgrading to Version 2.5

Users who have purchased a license for NetworkMiner Professional 2.x can download a free update to version 2.5 from our customer portal, or use the “Help > Check for Updates” feature. Those who instead prefer to use the free and open source version can grab the latest version of NetworkMiner from the official NetworkMiner page.

Posted by Erik Hjelmvik on Thursday, 07 November 2019 11:45:00 (UTC/GMT)

Tags: #NetworkMiner​ #JA3​ #HTTP/2​ #http2​ #DoH​ #Kerberos​ #PCAP​ #hashcat​ #John​ #NetworkMinerCLI​ #OSINT​

NetworkMiner 2.4 Released

We are proud to announce the release of NetworkMiner 2.4 today! The new version comes with several improvements, such as username extraction from Kerberos traffic, better OS fingerprinting and even better Linux support.

Protocol Updates

The Kerberos v5 implementation in NetworkMiner 2.4 can be used to to extract usernames, hostnames and realms (domains) from unencrypted Kerberos requests/responses on port 88. NetworkMiner also parses and extracts usernames etc. from HTTP auth headers and SMB security blobs when they use Kerberos for authentication.

NetworkMiner also automatically attempts to parse traffic to TCP port 11371 as HTTP in order to extract GPG keys sent using the HKP protocol.

MAC Address Magic

We’ve added two new features related to MAC addresses to this release. One of them is the “MAC Age” field (showing “2000-11-09” in the previous screenshot), which is a guesstimate of how hold a device/host is based on its MAC address. This functionality uses HD Moore’s mac-ages database, which contains approximate dates for when hardware address ranges were allocated by IEEE (original concept from DeepMac).

The second MAC feature is a simple yet useful feature that adds links between hosts that share the same MAC address. This feature is useful for linking a host's IPv6 and IPv4 addresses with each other, but it can also be used to track if a physical host has changed its IP address. The MAC address links can be accessed by expanding the MAC address node in NetworkMiner’s Hosts tab.

ICS Asset Inventory

We’ve put in some ground work in order to create OS fingerprinting signatures for several Industrial Control System (ICS) devices. Our signatures have been submitted and merged into Eric Kollmann’s Satori TCP database, which NetworkMiner uses to passively fingerprint hosts by examining various TCP and IP fields in the initial SYN/SYN+ACK packets of TCP sessions. The ICS devices we’ve added include PLCs, RTUs as well as rugged network equipment from vendors like ABB, Allen-Bradley, Modicon, Moxa, Phoenix Contact and Siemens. Some ICS vendors even got an icon showing their logo in the Hosts tab (see the Siemens/RUGGEDCOM device in the screenshot below) while the others got a yellow hard hat.

EternalBlue

NetworkMiner isn’t designed to be used as an IDS. Nevertheless we decided to add detection for the EternalBlue exploit to NetworkMiner 2.4. The fact that NetworkMiner parses NetBIOS and SMB makes it pretty straightforward to identify when an attacker is attempting to allocate a large non-paged pool in srvnet.sys by using a vulnerability in Microsoft’s SMB implementation (see MS17-010 for reference). This type of detection is difficult to perform using a standard IDS solution that cannot parse the NetBIOS and SMB protocols. Detected EternalBlue exploit attempts are listed in NetworkMiner's “Anomalies” tab. Example PCAP files with attackers/malware using the EternalBlue exploit can be found here:

• https://www.malware-traffic-analysis.net/2018/10/04/index.html
• https://www.malware-traffic-analysis.net/2018/08/17/index.html
• https://packettotal.com/app/analysis?id=c8850b1fe07572c82c6fac5db5aae0c9
• https://packettotal.com/app/analysis?id=8d2fdb7698c27e32e88bde809c89216f

NetworkMiner in Linux

NetworkMiner is a Windows tool, but it actually runs just fine also in other operating systems with help of the Mono Framework (see our guide “HowTo install NetworkMiner in Ubuntu Fedora and Arch Linux”). However, there are a few pitfalls that must be avoided to get the software running smoothly using Mono. With this release we’ve implemented workarounds for two bugs in Mono’s GUI implementation (System.Windows.Forms).

The first workaround handles a Mono bug that sometimes could be triggered by Drag-and-Dropping a file or image from NetworkMiner to another application, such as a browser, text editor or image viewer. Doing so would previously trigger a NullReferenceException in System.Windows.Forms.X11Dnd+TextConverter.SetData under certain conditions. We’re happy to report that you can now reliably drag and drop files extracted by NetworkMiner to other tools, even when running Linux.

The second workaround handles a bug in Mono’s GDIPlus implementation related to rendering of Unicode characters. We were unfortunately not able to reliably get Mono to render Unicode characters, NetworkMiner will therefore convert all Unicode MIME data to ASCII when using Mono (typically in Linux). Windows users will still get the proper Unicode representations of exotic characters and emojis in NetworkMiner though. ☺

NetworkMiner Professional

The commercial version of NetworkMiner, i.e. NetworkMiner Professional, comes with a few additional improvements. One of them is is that the following additional online sources have been added to the OSINT lookup feature:

• Wayback Machine (URL lookup)
• Alexa Rank (DNS lookup)
• Kaspersky Application Advisor (file hash lookup)

The CSV export from NetworkMinerCLI has been updated to use the ISO 8601 format with explicit time zone for timestamps. An exported timestamp now look something like this:

2019-01-08T13:37:00.4711000+02:00

NetworkMiner Professional 2.4 also identifies application layer protocols regardless of port number (a.k.a. PIPI) with much better precision than earlier versions. It also extracts audio from VoIP calls (SIP) more reliably than before.

Credits

I would like to thank Chris Sistrunk for requesting GUI support to link IPv4 and IPv6 hosts with the same MAC address and Jonas Lejon for the HKP GPG key extraction idea. I would also like to thank Phil Hagen for notifying us about the issue with Unicode in emails when running NetworkMiner under Mono and Ahmad Nawawi for notifying us about the protocol identification shortages in the previous version.

Upgrading to Version 2.4

Users who have purchased a license for NetworkMiner Professional 2.x can download a free update to version 2.4 from our customer portal. Those who instead prefer to use the free and open source version can grab the latest version of NetworkMiner from the official NetworkMiner page.

⛏ FOR GREAT JUSTICE! ⛏

Posted by Erik Hjelmvik on Thursday, 10 January 2019 14:20:00 (UTC/GMT)

Tags: #NetworkMiner​ #ICS​ #Kerberos​ #SIP​ #VoIP​ #IPv6​ #Mono​ #Linux​ #OSINT​ #PIPI​