NETRESEC Network Security Blog - Tag : Protocol Detection

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CapLoader 1.9.4 Released

CapLoader 1.9.4

A new version of our advanced PCAP filtering tool CapLoader was released today. The new CapLoader 1.9.4 release includes features like JA3 hash extraction from TLS traffic and a fantastic thing called Select Similar Flows, which is a unique feature that you will only find in CapLoader! We have also included a VXLAN parser, so that flows tunneled inside of overlay networks can be presented directly in the CapLoader GUI.

Select Similar Flows or Services

If you right-click a flow or service in CapLoader you’ll now be presented with an option to “select similar flows” (or services). This feature causes CapLoader to read through the loaded PCAP files again in order to find other flows that are similar to the one that was right-clicked. CapLoader doesn’t care about IP addresses or port numbers when assessing this similarity. Instead it looks at behavioral patterns in the traffic itself, such as packet sizes and byte patterns. In practice, this feature will select flows that are communicating using the same protocol as the one you clicked, regardless of which port it runs on. CapLoader already comes with an advanced feature for doing port-independent protocol identification, which currently detects over 170 protocols. But the “select similar” feature can even be used to find odd or proprietary protocols that aren’t in CapLoaders protocol database.

There is also a feature called “select VERY similar flows” which, instead of searching for flows with the same protocol, looks for flows with the same implementation or dialect of that particular protocol. This feature can be used to single out the network traffic of a particular software or tool from a haystack of network traffic from multiple applications, which all run the same application layer protocol. Another use case is to find additional malicious C2 sessions that run on top of a standard protocol like HTTP, TLS or DNS – provided that you’ve located at least one such malicious flow or service.

JA3 and JA3S Hashes for TLS Flows

We added JA3 extraction to NetworkMiner back in 2019, with the release of NetworkMiner 2.5. It’s now time to bring this useful little TLS fingerprinting feature into CapLoader as well. As of version 1.9.4 CapLoader attempts to extract JA3 and JA3S hashes from all TCP flows. The JA3 and JA3S hashes are presented in the Flows and Services tabs as separate columns. This allows users to filter flows based on a JA3 hash directly in CapLoader instead of having to export a filtered PCAP to an external tool to calculate JA3 hashes.

CapLoader with Column Critera filter for JA3 hash

Image: Column criteria filter “JA3 = a72f351cf3c3cd1edb345f7dc071d813” on PCAP from CERT-SE’s 2021 CTF.

Extraction of Flows Inside of VXLAN Tunnels

VXLAN is a network virtualization technology that can be used to create overlay networks, where Ethernet frames are encapsulated inside of UDP packets (see RFC 7348). The UDP port used for VXLAN is 4789 or 8472. We added support for VXLAN to NetworkMiner in 2017, but CapLoader has until now only presented the VXLAN tunnels in the GUI when VXLAN traffic is loaded. We’re happy to announce that CapLoader now extracts flows for the VXLAN tunnels and the traffic inside of those tunnels.

ICMP flow extracted from VXLAN tunnel

Image: ICMP flow extracted from VXLAN tunnel. PCAP file is Virtual_Extensible_LAN-VXLAN.pcap from Xena Networks

Additional GUI Improvements

We’ve also made several minor improvements to CapLoader’s user interface, such as a “Save Visible Flows” option on the File menu, which can be used to save the filtered traffic in the current view to a PCAP file. Another nice addition is the “Copy from Selected Rows” menu option, which can be used to copy text from a particular column.

CapLoader’s OSINT lookup context menus have also been updated to include some very useful services like Feodo Tracker, Hatching Triage and IPVoid.

Free Trial versus Full Version

Many of the new additions to CapLoader are only available in the full version, but the VXLAN extraction and some of the GUI additions are also available in the free trial version of CapLoader. No registration is required to download the trial — just download, extract and run for 30 days. If you like it, then please consider purchasing the full version!

Updating to the Latest Release

Users who have already purchased a license for CapLoader can download a free update to version 1.9.4 from our customer portal.

Posted by Erik Hjelmvik on Thursday, 16 June 2022 11:44:00 (UTC/GMT)

Tags: #CapLoader#JA3#JA3S#Protocol Identification#Protocol Detection#PCAP#TLS#VXLAN

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NetworkMiner 2.7.3 Released

NetworkMiner 2.7.3

NetworkMiner now extracts meterpreter payloads from reverse shells and performs offline lookups of JA3 hashes and TLS certificates. Our commercial tool, NetworkMiner Professional, additionally comes with a packet carver that extracts network packets from memory dumps.

Extraction of Meterpreter Payloads

NetworkMiner 2.7.3 supports extraction of meterpreter DLL payloads from reverse shell TCP sessions deployed with Metasploit. The free version of NetworkMiner will try to extract the meterpreter DLL from TCP sessions going to "poker-hand ports" commonly used for meterpreter sessions, such as 3333, 4444, 5555, etc. The port-independent protocol detection feature available in NetworkMiner Professional additionally enables extraction of meterpreter DLLs regardless which LPORT the attacker specifies when deploying the reverse shell.

Meterpreter DLL extracted from PCAP file in NetworkMiner Professional

Image: Meterpreter DLL extracted from DFIR Madness' case001.pcap

Packet Carving in NetworkMiner Professional

If you try to open anything other than a PCAP, PcapNG or ETL file in NetworkMiner Professional, then you'll be presented with an option to carve packets from the opened file as of this release.

NetworkMiner Unknown Capture File Format

The packet carver can extract packets from any structured or unstructured data, such as memory dumps and proprietary packet capture formats. NetworkMiner Pro's carver is a simplified version of the packet carving feature in CapLoader.

Loading the 1GB "memdump.mem" from Ali Hadi's Challenge #1 - Web Server Case into NetworkMiner Professional takes roughly five seconds, during which 612 packets get extracted.

NetworkMiner Professional with packets extracted from memory dump

Image: Information about network hosts carved from memory dump

In this scenario the memory was dumped on the host, which NetworkMiner identifies as "WIN-L0ZZQ76PMUF". The carved packets also indicate that this computer had an outgoing TCP connection to, which appears to be a Linux machine called "kali". As you can see in the screenshot, the packets carved from the memory dump also reveal a great deal about other hosts on the network, such as the host, which seems to be a Windows 7 machine called "IT104-00".

Offline Matching of JA3 and X.509 hashes

NetworkMiner 2.7.3 comes with a local copy of the SSL Certificate and JA3 Fingerprint Blacklists from the awesome project. JA3 hashes and extracted X.509 certificates are matched against these lists in order to see if they are associated with any piece of malware or botnet.

Here's one example showing the default Cobalt Strike certificate being identified as "AKBuilder C&C", since that's how it is listed in's SSL certificate database.

CobaltStrike default X.509 certificate

Image: Cobalt Strike's default certificate identified as "AKBuilder C&C"
PCAP: Cobalt Strike PCAP from

The port-independent protocol detection feature in NetworkMiner Professional additionally enables X.509 certificates to be extracted even from non-standard TLS ports, such as this certificate, which is identified as "BitRAT" with help of the certificate block-list.

NetworkMiner Professional with BitRAT TLS traffic

Image: Both X.509 certificate and JA3 hash identified as BitRAT
PCAP: BitRAT PCAP from Joe Sandbox

The client's JA3 hash 8515076cbbca9dce33151b798f782456 is also associated with BitRAT according to

DBSBL Lookup Detection

DNSBL services are used by servers handling incoming email to verify that the sender's IP address isn't a known SPAM sender and that it isn't from a network that shouldn't be sending emails.

But DNSBL services can also be used by malware and botnets, such as TrickBot and Emotet, to verify that the public IP of a victim is allowed to send emails and that it hasn't already been blacklisted for sending SPAM. We have therefore decided to add DNSBL lookups to the Host Details section in NetworkMiner 2.7.3.

DNSBL lookups in NetworkMiner

Image: TrickBot victim checks if its public IP is blocked by DNSBL services
PCAP: TrickBot PCAP from

DNSBL lookups are also logged to the "Parameters" tab of NetworkMiner.

NetworkMiner with DNSBL parameters

Image: NetworkMiner's Parameters tab with "DNSBL" filter
PCAP: TrickBot PCAP from

Additional Features and Updates

We'd also like to mention some additional new features, bug fixes and improvements that have been included in this new release.

  • Support for HTTP CONNECT request method to extract artifacts like X.509 certificates and JA3 hashes from HTTPS traffic passing through a web proxy.
  • Traffic to TCP ports 3000 and 8000 are now configured to be parsed as HTTP by default in order to handle WEBrick traffic.
  • Improved extraction of SMTP credentials.
  • JA3 hashes were previously incorrect for clients that supported more than one EC point format (RFC 8422). This has now been fixed.
  • Support for SLL2 (Linux cooked capture v2) frames.
  • Improved handling of concurrent GUI events, for example when poking around in the "Hosts" tab while loading a PCAP file or doing live sniffing.
  • NetworkMiner's GUI no longer reloads between each PCAP file when multiple files are loaded at once.

New Features in NetworkMiner Professional

We have also added a few new features exclusively to NetworkMiner Professional, which is the commercial version of NetworkMiner. Apart from the packet carver feature, mentioned earlier in this blog post, we've also updated the collection of OSINT lookup services available in the GUI. One of the newly added services is Ryan Benson's unfurl, which picks apart URLs to reveal data that might have been encoded into a complex URL. The unfurl lookup can be found by right-clicking an URL in NetworkMiner Professional's "Browsers" tab and selecting the "Lookup URL" sub menu.

Other OSINT services that we've added are FileScan.IO and JoeSandbox lookups of extracted files. These lookups can be performed by right clicking a file in the "Files" tab and opening the sub-menu called "Lookup Hash".

Lookup of file hash on JoeSandbox

Image: OSINT lookup of an EXE file extracted from network traffic

The command-line version of NetworkMiner Professional, NetworkMinerCLI, has also been updated to allow extracted information to be printed directly on standard output instead of logging everything to files. Here is an example showing this feature while running NetworkMinerCLI in Linux (with help of Mono):

mono /opt/NetworkMinerProfessional_2-7-3/NetworkMinerCLI.exe -r 2022-03-14-Qakbot-with-Cobalt-Strike-and-VNC-module.pcap -w /tmp/malware -X FileInfos | cut -d, -f 5,9
"Microsoft RSA TLS CA 01.cer","806f1c72f6d67c9c114eff43d3d84100"
"Microsoft RSA TLS CA 02.cer","65d17ecae5798c79db8e840fe98a53b9"

The command above extracts files from a PCAP file, which contains traffic from a Windows PC infected with Qbot. The "-w" switch specifies the output directory for the files extracted from network traffic, and the "-X FileInfos" specifies that metadata for these files should be sent to STDOUT instead of being written to log files. The cut utility was used to show only the filename (column 5) and MD5 hash (column 9) of the file info output.

The MD5 hashes of the extracted files confirm that this is indeed a Qbot infection:

  • 124207bc9c64e20e114bcaeabde12a4e (VT)
  • ca7ef367c935182a40a95b9ad8b95f42 (VT)
  • a9a8366fa6be54b45ca04192ca217b75 (VT)

NetworkMinerCLI previously printed some information about the parsing process to STDOUT. That output has now been moved to STDERR in order to provide the "-X [type]" output with exclusive access to STDOUT.


We'd like to thank Michael Taggart for noticing that NetworkMiner previously failed to parse HTTP traffic to ports 3000 and 8000.

Upgrading to Version 2.7.3

Users who have purchased NetworkMiner Professional can download a free update to version 2.7.3 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 Monday, 04 April 2022 06:52:00 (UTC/GMT)

Tags: #NetworkMiner#carve#JA3#X.509#CobaltStrike#Cobalt Strike#TrickBot#Emotet#PIPI#Protocol Detection#OSINT#NetworkMinerCLI

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