Network Forensics Training - Spring 2024

I will teach two live online network forensics classes in March, one on European morning time, and the other on US morning time. The subject for both classes is network forensics in an incident response context.

The training is split into four interactive morning sessions, so that you have the afternoon free to either practice what you learned in class or catch up with your “normal” day job. The number of attendees will be limited in order to provide a good environment for taking questions. A maximum of 15 attendees will be accepted per class. The registration will be closed once we reach this attendee limit.

• 🇪🇺 March 4-7, 2024: PCAP in the Morning Europe
  ⏲️ Time: 8:30 AM to 12:30 PM CET
  💸 Price: € 930 EUR per student
• 🇺🇸 March 25-28, 2023: PCAP in the Morning US
  ⏲️ Time: 9:30 AM to 1:30 PM EDT
  💸 Price: $1,000 USD per student

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! In this training you'll get first-hand experience looking at C2 and backdoor protocols, such as Cobalt Strike, TrickBot, njRAT and Meterpreter.

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!

Cheers,
Erik Hjelmvik
Creator of NetworkMiner and founder of Netresec

Posted by Erik Hjelmvik on Monday, 11 December 2023 12:55:00 (UTC/GMT)

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

CapLoader 1.9.6 Released

CapLoader now detects even more malicious protocols and includes several new features such as JA4 fingerprints, API support for sharing IOCs to ThreatFox and OSINT lookups of malware families on Malpedia. The new CapLoader 1.9.6 release also comes with several improvements of the user interface, for example interactive filtering of flows and services with regular expressions.

Detection of Malware C2 Protocols

Malware authors continually keep coming up with new C2 protocols for defenders to detect. Luckily we don’t need to manually create protocol signatures for CapLoader, we only need a few examples of traffic for a protocol to generate a statistical model that CapLoader can use to detect that protocol. We call this feature Port Independent Protocol Identification (PIPI).

We’ve added support for detecting of the following protocols in this new release of CapLoader:

Image: Protocols identified in PCAP files with malware traffic from various sandboxes (ANY.RUN, Hybrid-Analysis, Joe Sandbox and Triage)

Our PIPI feature can also detect protocols inside of other protocols, such as Cobalt Strike, DCRat, Emotet, Formbook, Gozi ISFB, GzipLoader and Socks5Systemz which all run on top of HTTP. It is sometimes even possible to identify malicious protocols that use TLS encryption, such as AsyncRAT, Cobalt Strike, Emotet, IcedID or Remcos. However, detection of malicious TLS encrypted protocols is a difficult challenge and might be subject to false positives.

Sharing IOCs to ThreatFox

ThreatFox is a free online service for sharing indicators of compromise (IOCs) from malware. ThreatFox can be queried for a particular malware family, such as RedLine Stealer, and it’ll return a list of URLs, domain names and IP:port pairs used for C2 communication or payload delivery for that malware. You can also query for a domain or IP address to see if it’s a known C2 address of any malware or botnet.

CapLoader has supported OSINT lookup of IP addresses and domains on ThreatFox since the release of version 1.9, but with this release we also add the ability to contribute by sharing IOCs with the infosec community. All you need to do is to enter your ThreatFox API-key in CapLoader’s settings, then right-click a flow, service or alert and select “Submit to ThreatFox”.

Image: Submission of microsoft.net.linkpc[.]net to ThreatFox

If the right-clicked item is an alert for a “Malicious protocol” then CapLoader will automatically populate the Mapledia Name field, as shown in the screenshot (win.loda).

TLS Client Fingerprinting with JA4

John Althouse announced the new JA4+ fingerprint methods a couple of months ago on the FoxIO blog. In short JA4+ is a suite of methods designed to fingerprint implementations of a specific set of protocols, including TLS, HTTP and SSH. As you’ve probably guessed JA4+ is a successor to the JA3 and JA3S hashes that we’ve learned to love (we added JA3 fingerprinting to NetworkMiner in 2019).

Most of the fingerprinting methods in the JA4+ suite are patent pending except for the TLS client fingerprinting method “JA4”, which FoxIO does not have patent claims and is not planning to pursue patent coverage for. We have therefore built a JA4 fingerprinting engine that we’ve included in this CapLoader release. Future releases of NetworkMiner will hopefully also include our JA4 fingerprinting engine.

Image: JA3 and JA4 hashes of Remcos C2 traffic

JA4 is similar to JA3 in many ways, but one essential difference is that JA4 fingerprints are something of a fuzzy hash of the client’s handshake rather than a MD5 hash of the raw fingerprint. JA3’s use of MD5 hashing has received criticism, for example in academic literature, partly due to the inability to see if two JA3 hashes have similar TLS handshakes.

JA4 does use hashes, but instead of just being one big hash it breaks the fingerprint into three separate sections; where the first section is used in its raw (non-hashed) format and the other two sections are hashed separately. Thus, an update of a TLS implementation, which only adds one additional cipher, will increment the cipher counter in the first section of the JA4 fingerprint by one and the ciphers hash (second section) will get a new value. The hash in the last section will remain intact.

In the previous CapLoader screenshot with Remcos C2 traffic we see TLS handshakes that have the same JA3 hash (a85be79f7b569f1df5e6087b69deb493) but the JA4 fingerprints have different values (t13i010400_0f2cb44170f4_5c4c70b73fa0 and t13i010400_0f2cb44170f4_1b583af8cc09). The reason why the last JA4 section is different even though the JA3 hash is the same is because some of these TLS handshakes present a different set of signature algorithms, which is a parameter that isn't being used in JA3.

Alerts Tab

CapLoader’s Alerts tab now includes more alert types than before and each alert has a severity rating graded as follows:

• High = 4
• Medium = 3
• Low = 2
• Info = 1

A typical high-severity alert is when a known malicious protocol is detected, while an “Info” type alert can provide a heads up about traffic from things like coin mining or legitimate remote admin tools. As you can see in the screenshot below the alerts are sorted based on severity to make it easier to prioritize them.

Image: CapLoader alerts for 2023-10-16-IcedID-infection.pcap

Here’s a breakdown of the alerts shown in the CapLoader screenshot above:

• GzipLoader traffic to 104.21.7.13:80 / aptekoagraliy[.]com
• BackConnect XOR traffic to 159.89.124.188:443
• IcedID over TLS traffic to 104.223.118.109:443 / seedkraproboy[.]com
• Port-protocol mismatch (non-TLS traffic to port 443) for 159.89.124.188:443
• Periodic connections every 5 minutes to 151.236.9.107:443 / lazirusairnaf[.]com
• Periodic connections every 5 minutes to 104.223.118.109:443 / seedkraproboy[.]com
• Long running TCP session to 159.89.124.188:443
• Long running TCP session to 104.248.81.48:443 / joekairbos[.]com

All these alerts are indicators of an IcedID infection, including the 5 minute C2 connection interval which I have mentioned before.

Other User Interface Improvements

CapLoader’s “Column Criteria” row filter could previously only be used to filter on columns with a specific value, such as “Protocol = TLS”. This new release of CapLoader additionally allows users to do substring matching with the “contains” keyword and regular expression (regex) matching with the “matching” keyword. In the screenshot below the Column Criteria “Hostname matches \.local$” is used to only show hosts that have a hostname ending with “.local”.

We’ve also added an often asked for feature to CapLoader, namely the ability to switch between different flows in the Transcript window.

The flows you can switch between depends on how the transcript window was opened. A flow transcript opened from the Flows tab will allow switching between the flows that were visible in the list from where the transcript was opened. A transcript opened from any of the other tabs (Services, Hosts or Alerts), on the other hand, allows switching between the different flows for the particular service, host or alert that was opened.

Credits

I would like to thank Nic Cerny, Trent Healy and Fredrik Ginsberg for their input on various improvements that have been implemented in CapLoader 1.9.6.

Updating to the Latest Release

Users who have already purchased a license for CapLoader can download a free update to version 1.9.6 from our customer portal or by clicking “Check for Updates” in CapLoader’s Help menu.

Posted by Erik Hjelmvik on Wednesday, 15 November 2023 12:08:00 (UTC/GMT)

Tags: #CapLoader​ #ThreatFox​ #JA3​ #IcedID​ #GzipLoader​ #regex​

Forensic Timeline of an IcedID Infection

The BackConnect and VNC parsers that were added to NetworkMiner 2.8.1 provide a unique possibility to trace the steps of an attacker with help of captured network traffic from a hacked computer.

In this blog post I use the free and open source version of NetworkMiner to see how GzipLoader downloads IcedID, after which the attacker deploys BackConnect VNC to purchase an iPhone 14 with a stolen credit card and then drops Cobalt Strike on the victim PC.

The analyzed pcap is 2022-10-31-IcedID-with-DarkVNC-and-Cobalt-Strike-full-pcap-raw.pcap from Brad Duncan's malware-traffic-analysis.net blog.

Safety First

I ran NetworkMiner in a Windows Sandbox when analyzing this PCAP file to avoid accidentally infecting my computer with any of the malicious artifacts that NetworkMiner extracts from the network traffic.

Another safe way to analyze Windows malware is to run NetworkMiner in Linux or macOS.

14:47 GzipLoader

This infection starts with GzipLoader (aka “IcedID Downloader”) reaching out to its C2 server on vgiragdoffy[.]com (67.205.184.237:80) to download IcedID.

The “_gat” cookie value in frame number 6 tells us that the victim machine is running a Windows 10 build 19045 (aka 22H2). The long “_u” value contains the victim’s username and hostname in hexadecimal representation and the “__io” value is the logged in user’s SID. NetworkMiner decodes these values from the GzipLoader request and displays them in the Hosts tab.

For more info about the GzipLoader cookie, see IcedID PhotoLoader evolution by Jason Reaves and the eSentire blog post on Gootloader and IcedID.

The response for this GzipLoader request is a 550 kB file (MD5 700c602086590b05dde8df57933c7e68) with a fake gzip header. This file actually contains the IcedID DLL (Odwikp.dll) and license.dat files.

14:47 IcedID

The banking trojan IcedID (aka BokBot) gets launched at 14:47:29 UTC (frame 641) after which it connects to these four IcedID servers used for payload delivery and C2:

• ringashopsu[.]com = 137.184.208.116
• sainforgromset[.]com = 138.68.255.102
• yeloypod[.]hair = 94.140.114.103
• airsaintol[.]beauty = 66.63.168.75

These four IcedID servers all run TLS servers with self signed certificates issued for "localhost" and doing TLS handshakes with JA3S hash ec74a5c51106f0419184d0dd08fb05bc. Both these properties can be used as filters in NetworkMiner's Hosts tab to only display the IcedID C2 servers.

14:59 BackConnect and Keyhole VNC

Shortly after the IcedID C2 traffic has been started the IcedID bot also initiates BackConnect C2 connections to 137.74.104.108 on TCP port 8080 (frame 4505 at 14:59:14 UTC).

The BackConnect C2 server tells the bot to sleep for 60 seconds two times before launching a reverse VNC session with command 0x11 (frame 4530 at 15:01.09 UTC).

15:06 Apple Store

The keylog of the attacker above reveals that the attacker is typing “iphone 14 apple store buy”. The VNC graphics that NetworkMiner extracted from the PCAP file additionally reveal that this was a Google search query typed into an Edge browser.

15:10 Credit Card payment

The attacker proceeds to the Apple Store, puts a black iPhone 14 Plus for $987.99 into the shopping cart, enters a delivery address in West Hartford (US) and then inputs credit card details for the payment.

Luckily, the transaction was denied by Apple Store.

15:12 Reverse Shell

After having failed to buy an iPhone through the hacked computer the attacker instead deploys three reverse shell sessions using the BackConnect C2 channel.

These three commands are issued in the first reverse shell session:

In the second shell session the attacker first runs these three commands:

...and then starts a file manager session through the BackConnect C2 channel.

15:40 Deploy Cobalt Strike

The BackConnect file manager is used to upload a Cobalt Strike binary called P2.dll to "C:\ProgramData\" on the victim computer in frame 144535.

The uploaded P2.dll is then executed by running this command in the reverse shell session (frame 144707):

NetworkMiner extracts this uploaded DLL from the BackConnect network traffic.

As you can see in the screenshot above, the MD5 hash of P2.dll is cc69a31a067b62dda5f2076f8ee335e1. This file is flagged as malicious by most AV vendors (P2.dll on VT). However, none of them label it as Cobalt Strike. Luckily I was able to use Triage's malware config extractor to verify that this was indeed Cobalt Strike (P2.dll on tria.ge). Triage also revealed that the CobaltStrike C2 URL was
clouditsoft[.]com:8008/static-directory/mg.jpg

After the DLL gets executed the victim PC establishes Cobalt Strike beacon C2 connections to clouditsoft[.]com on port 8008 (frame 144715).

15:41 MOAR COBALT STRIKE

The BackConnect Reverse Shell log in NetworkMiner's Parameters tab shows that the attacker also attempted to download Cobalt Strike using PowerShell at 15:41:59 UTC (frame 145176) with this command:

IOC List

• IP:port 67.205.184.237:80 (GzipLoader)
• DNS vgiragdoffy[.]com (GzipLoader)
• MD5 700c602086590b05dde8df57933c7e68 (Fake gzip file)
• MD5 f57ab2e5e5720572d5eb19010ec8dcb4 (IcedID Odwikp.dll from fake gzip)
• MD5 57a9d9acb389bd74a7423a16ef81ac18 (IcedID license.dat from fake gzip)
• DNS ringashopsu[.]com (IcedID C2)
• DNS sainforgromset[.]com (IcedID C2)
• DNS yeloypod[.]hair (IcedID C2)
• DNS airsaintol[.]beauty (IcedID C2)
• IP:port 137.184.208.116:443 (IcedID C2)
• IP:port 138.68.255.102:443(IcedID C2)
• IP:port 94.140.114.103:443 (IcedID C2)
• IP:port 66.63.168.7:443 (IcedID C2)
• JA3S hash ec74a5c51106f0419184d0dd08fb05bc (IcedID C2)
• IP:port 137.74.104.108:8080 (IcedID BackConnect C2)
• MD5 cc69a31a067b62dda5f2076f8ee335e1 (CobaltStrike P2.dll)
• DNS clouditsoft[.]com (CobaltStrike C2)
• IP:port 198.44.140.67:8008 (CobaltStrike C2)

Posted by Erik Hjelmvik on Thursday, 12 October 2023 13:23:00 (UTC/GMT)

Tags: #NetworkMiner​ #IcedID​ #GzipLoader​ #BackConnect​ #VNC​ #CobaltStrike​ #Cobalt Strike​ #Windows Sandbox​ #ec74a5c51106f0419184d0dd08fb05bc​ #JA3S​

NetworkMiner 2.8.1 Released

I am happy to announce the release of NetworkMiner 2.8.1 today!

This new release brings a VNC parser to NetworkMiner, so that screenshots, keystrokes and clipboard data can be extracted from unencrypted VNC traffic. NetworkMiner 2.8.1 additionally includes parsers for command-and-control (C2) protocols used by njRAT, IcedID, QakBot and Bazar. We have also added extraction of files sent using a HTTP PUT request, which is the rare cousin to the more common POST request. NetworkMiner’s Images tab has also been updated to enable filtering based on filename or pixel count.

VNC

NetworkMiner now supports the remote framebuffer (RFB) protocol (RFC 6143), which is the underlying protocol used in VNC software. VNC is used to remotely control another computer with help of a real-time video feed of the remote computer’s screen and the ability to control the remote desktop using a mouse and keyboard.

NetworkMiner reassembles the desktop graphics that get transferred between a VNC client and server to build a local representation of the remote desktop. Screenshots of that desktop then get extracted to disk by NetworkMiner as it gets updated. These desktop screenshots can be viewed in NetworkMiner’s Images tab. NetworkMiner also extracts keystrokes and clipboard data from the VNC traffic and displays them in the Parameters tab.

Limitations in VNC Extraction

Essential configuration of the VNC session is set up in the beginning of each TCP session. NetworkMiner therefore requires analyzed traffic to include this initial setup in order to successfully extract graphics from a VNC session.

Only traffic to TCP ports 5900 and 5901 will be parsed as VNC traffic by the free version of NetworkMiner. Our commercial tool NetworkMiner Professional has the ability to identify VNC traffic regardless of port number, but the free version will fail to extract screenshots from VNC traffic running on non-standard ports.

NetworkMiner’s VNC implementation is currently at an early stage, which is why it might fail to extract screenshots or other data from VNC sessions. If you encounter VNC traffic that NetworkMiner fails to parse, then we’d be very grateful if you would contact us and let us know so that we can improve NetworkMiner’s VNC extraction in future releases.

BackConnect

I have previously outlined the BackConnect protocol used by IcedID, QakBot as well as Bazar. This BackConnect protocol is used by botnet operators to remotely control a victim computer using a form of remote access trojan (RAT). This BackConnect protocol supports features such as tunneling network traffic through the victim’s computer, uploading files and the ability to control the victim’s computer using VNC.

NetworkMiner now has a parser for this BackConnect protocol, which allows analysts to see screenshots, keystrokes and file uploads from when the attacker interacts with the hacked computer. As you might have guessed, NetworkMiner’s VNC parser is reused in order to also parse reverse VNC traffic from BackConnect sessions.

I would like to thank Maxime Thiebaut for releasing his PCAPeek tool, which also reassembles reverse VNC traffic from BackConnect traffic. Maxime’s tool proved that it was possible to extract graphics from this C2 traffic, which motivated me to create a BackConnect VNC parser for NetworkMiner.

BackConnect VNC Replay

To demonstrate NetworkMiner’s reverse VNC reassembly I’d like to use the file “2023-07-26-IcedID-with-Keyhole-VNC-traffic.pcap” from Brad Duncan’s fantastic malware-traffic-analysis.net website. In this traffic the IcedID BackConnect C2 server listens to TCP port 443 on 165.232.175.216.

The screenshot thumbnails from the BackConnect VNC traffic shows that the attacker opens up the Amazon website on the victim’s computer. A copy of the full 1920x1152 screenshot, which NetworkMiner extracted from the VNC traffic, can be viewed here: VNC_73F81C83_230726142247.jpg

The parameters tab in NetworkMiner additionally confirms that the attacker manually typed “amazon.com” into the hacked computer’s web browser.

Limitations in BackConnect Parser

The BackConnect implementation in NetworkMiner 2.8.1 is pretty well tested and even supports the new “encrypted” version of BackConnect that IcedID has been deploying lately (we call it “BackConnect XOR”). NetworkMiner can parse the BackConnect C2 traffic as well as the traffic from modules for reverse VNC, reverse SOCKS, reverse shell and the file manager.

Unfortunately the BackConnect traffic typically runs on TCP ports like 443 or 8080, which are normally used for TLS or web proxies. The free open source version of NetworkMiner normally attempts to interpret traffic to port 443 as TLS and 8080 as HTTP proxy, even though it might be BackConnect. A hardcoded list of 32 verified BackConnect C2 servers, such as 165.232.175.216:443, 137.184.172.23:443 and 185.99.132.16:8080, has therefore been added to NetworkMiner’s source code. This enables NetworkMiner to interpret traffic to those IP:port combinations as BackConnect. Our commercial tool NetworkMiner Professional can identify protocols without relying on the port number though, this enables the “Pro” version to also parse BackConnect traffic to C2 servers that aren’t among the 32 hard coded ones in the source code.

njRAT

njRAT is an old, yet still very popular remote access trojan (RAT). It has been around for at least 10 years (since 2013) and can be used to do things like:

• Steal credentials
• Take screenshots of the desktop
• Start the camera
• Record audio with the microphone
• Start a reverse shell
• Upload or download files
• Execute a file or module
• Capture keystrokes with a keylogger
• Create, read or delete registry keys
• Run a command

I have been teaching students in my network forensics classes how to manually parse njRAT traffic since 2015, but from now on I’ll instead be able to tell them to load the njRAT traffic into NetworkMiner to see what the attacker did on the victim’s computer.

The NetworkMiner parameters and victim PC screenshot above were extracted from 2015-04-22_capture-win4.pcap in StratosphereIPS’ dataset CTU-Malware-Capture-Botnet-120-1. The victim PC desktop screenshot actually came out as a 51x4900 pixel image in NetworkMiner 2.8.1, so I had to manually reorganize the tiles to a 510x490 image instead. I’m planning to add an automatic retiling feature to NetworkMiner to avoid having to do this manually in the future.

Limitations in njRAT Parser

njRAT comes in many different versions, forks and flavors and the protocol even has a field delimiter sequence that can be customized for each njRAT backdoor. I can therefore not guarantee that NetworkMiner will be able to parse traffic from all njRAT sessions, but so far I’ve seen very good results – even when custom field delimiters are being used.

Nevertheless, this trojan has an abundance of features but only the most commonly used ones are implemented in NetworkMiner. More specifically NetworkMiner primarily supports extraction of screenshots, credentials, keylog data, file uploads and downloads. NetworkMiner also extracts exfiltrated metadata about the victim machine and bot, such as the hostname, operating system, logged in user, bot ID, botnet, njRAT version and njRAT install date.

Also, as previously mentioned, NetworkMiner doesn’t yet stitch together tiles of desktop screenshots correctly.

Another limitation is that an njRAT C2 server can be deployed on any TCP port, which might prevent the free version from interpreting the C2 traffic as njRAT. The free version of NetworkMiner currently tries to parse traffic to ports like 1177, 5050, 5552 and a few others as njRAT, while NetworkMiner Professional will automatically recognize the njRAT protocol regardless which port it runs on.

Bug Fixes

We’ve added support for SIP keepalive messages (RFC 5626) in NetworkMiner 2.8.1. NetworkMiner Professional would previously fail to extract VoIP calls, or text messages sent through SIP, if a keepalive packet was sent in the session prior to the call or text message. We have also fixed a bug in NetworkMiner’s CapWap parser.

Upgrading to Version 2.8.1

Users who have purchased NetworkMiner Professional can download a free update to version 2.8.1 from our customer portal, or use the “Check for Updates” feature from NetworkMiner's Help menu. 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, 02 October 2023 11:13:00 (UTC/GMT)

Tags: #NetworkMiner​ #VNC​ #BackConnect​ #IcedID​ #njRAT​

EvilExtractor Network Forensics

I analyzed a PCAP file from a sandbox execution of the Evil Extractor stealer malware earlier today. This stealer collects credentials and files of interest from the victim’s computer and exfiltrates them to an FTP server. It is designed to autonomously collect and exfiltrate data rather than receiving commands from an operator through a command-and-control channel. The EvilExtractor creators market this feature as a “golden bullet”.

Real hackers don’t use reverse shells right? If you have only one bullet, would you waste with reverse shell? Try Evil Extractor to have golden bullet.

I downloaded the Evil Extractor capture file from Triage to a Windows Sandbox environment, to avoid accidentally infecting my computer when extracting artifacts from the PCAP. I then opened it up in the free version of NetworkMiner.

NetworkMiner shows that after checking its public IP on ipinfo.io EvilExtractor makes an unencrypted HTTP connection to a web server on 193.42.33.232 to download KK2023.zip. This zip archive contains a file called “Lst.exe” which is used to steal browser data, cookies and credentials according to Fortinet.

Twenty seconds later an FTP connection is established to 89.116.53.55 on TCP port 21. The username and password used to authenticate to the FTP server was “u999382941” and “Test1234”.

On the FTP server EvilExtractor creates a directory named after the country and hostname of the victim's PC, such as “(Sweden)DESKTOP-VV03LJ”, in which it creates the following three sub directories:

• 1-Password-Cookies
• 2-Credentials
• 3-Files

After uploading browser cookies, browser history and cached passwords from Chrome, Firefox and Edge to the “1-Password-Cookies” directory EvilExtractor sends a file called “Credentials.txt” to the “2-Credentials” directory. The contents of this text file looks something like this:

Public IP: [redacted]
Location: [lat],[long]
Computer Name: [redacted]
Username: Admin
RAM: 4 GB
OS Name: Microsoft Windows 10 Pro
OS Bit: 64-bit
Keyboard Language: en-US
GPU: [redacted]
CPU: Intel [redacted]
MAC Address: [redacted]
Extracted WIFI: [redacted]

The stealer also exfiltrates files with mpeg, docx, jpeg, pptx, zip, avi and rar extensions from the victim PC to the “3-Files” directory on the FTP server. The directory structure of the victim’s PC is maintained on the FTP server, so that files from the victim's desktop end up in a folder called “Desktop” on the FTP server.

The stealer later downloaded a keylogger module (Confirm.zip) and a webcam module (MnMs.zip), but no additional data was exfiltrated from this particular victim PC after that point.

IOC List

• Web server: 193.42.33.232:80
• FTP server: 89.116.53.55:21
• EvilExtractor: 9650ac3a9de8d51fddab092c7956bdae
• KK2023.zip: f07b919ff71fb33ee0f77e9e02c5445b
• Lst.exe: 163d4e2d75f8ce6c838bab888bf9629c
• Confirm.zip: 30532a6121cb33afc04eea2b8dcea461
• Confirm.exe: 0c18c4669e7ca7e4d21974ddcd24fdca
• MnMs.zip: bda0bda512d3e2a81fc9e4cf393091eb
• MnMs.exe: fb970c4367609860c2e5b17737a9f460

Users with an account on Triage can download the analyzed PCAP file from here: https://tria.ge/230424-vv9wvsfb2v/behavioral2

Update 2023-04-27

Jane tweeted a link to an execution of this same sample on ANY.RUN. This execution showed very similar results as the one on Triage, but with an interesting twist. Not only did the ANY.RUN execution exfiltrate images and documents from the Desktop and Downloads folders, it also exfiltrated “vv9wvsfb2v_pw_infected.zip”, which contained the EvilExtractor EXE file that was being run!

The PCAP from the ANY.RUN execution can be downloaded from here: https://app.any.run/tasks/43a11a79-4d1f-406c-86d7-158efb5ede01/

Posted by Erik Hjelmvik on Wednesday, 26 April 2023 08:50:00 (UTC/GMT)

Tags: #FTP​ #NetworkMiner​ #Sandbox​ #Triage​ #ANY.RUN​

QakBot C2 Traffic

In this video I analyze network traffic from a QakBot (QBot) infection in order to identify the Command-and-Control (C2) traffic. The analyzed PCAP file is from malware-traffic-analysis.net.

IOC List

• C2 IP and port: 80.47.61.240:2222
• C2 IP and port: 185.80.53.210:443
• QakBot proxy IP and port: 23.111.114.52:65400
• JA3: 72a589da586844d7f0818ce684948eea
• JA3S: ec74a5c51106f0419184d0dd08fb05bc
• JA3S: fd4bc6cea4877646ccd62f0792ec0b62
• meieou.info X.509 cert hash: 9de2a1c39fbe1952221c4b78b8d21dc3afe53a3e
• meieou.info X.509 cert Subject OU: Hoahud Duhcuv Dampvafrog
• meieou.info X.509 cert Issuer O: Qdf Wah Uotvzke LLC.
• gifts.com X.509 cert hash: 0c7a37f55a0b0961c96412562dd0cf0b0b867d37
• HTML Body Hash: 22e5446e82b3e46da34b5ebce6de5751664fb867
• HTML Title: Welcome to CentOS

Links

• QakBot PCAP download (malware-traffic-analysis.net)
• 80.47.61.240 (VirusTotal)
• 80.47.61.240:2222 (ThreatFox)
• 80.47.61.240 (Feodo Tracker)
• 80.47.61.240 (Censys)
• 185.80.53.210 (Censys)

For more analysis of QakBot network traffic, check out my Hunting for C2 Traffic video.

Posted by Erik Hjelmvik on Thursday, 02 March 2023 12:43:00 (UTC/GMT)

Tags: #QakBot​ #QBot​ #C2​ #Video​ #malware-traffic-analysis.net​ #ThreatFox​ #ec74a5c51106f0419184d0dd08fb05bc​ #fd4bc6cea4877646ccd62f0792ec0b62​ #CapLoader​ #NetworkMiner​

TLS Redirection and Dynamic Decryption Bypass in PolarProxy

PolarProxy is constantly being updated with new features, enhanced performance and bug fixes, but these updates are not always communicated other than as a short mention in the ChangeLog. I would therefore like to highlight a few recent additions to PolarProxy in this blog post.

Custom TLS Redirection

One new feature in PolarProxy is the --redirect argument, which can be used to redirect TLS traffic destined for a specific domain name to a different domain. This feature can be used to redirect TLS-encrypted malware traffic going to a known C2 domain to a local HTTPS sandbox instead, for example INetSim.

This --redirect argument will cause PolarProxy to terminate outgoing TLS traffic to malware-c2.com and redirect the decrypted traffic into a new TLS session going to inetsim.local instead. The “--leafcert noclone” argument forces PolarProxy to generate a fake X.509 certificate for “malware-c2.com” rather than sending a clone of the certificate received from the INetSim server to the malware implant.

Note: You also need to specify a proxy mode, such as -p for transparent proxy or --socks for SOCKS proxy, to make the command above work.

The --redirect argument can also be used to perform domain fronting, which is a clever method for hiding the true destination of HTTPS based communication, in order to circumvent censorship or for other reasons conceal who you’re communicating with. The following command can be used to set up a local socks proxy that redirects traffic destined for YouTube to google.com instead:

A browser configured to use PolarProxy as a SOCKS proxy will send HTTPS requests for youtube.com to PolarProxy, which then decrypts the TLS layer and re-encrypts the HTTP communication in a new TLS session directed at google.com instead. Someone who monitors the outgoing traffic from PolarProxy will assume that this is normal Google traffic, since the SNI as well as certificate will be for google.com. On the server side however, after having decrypted the TLS layer, Google will kindly forward the client’s original HTTP request for youtube.com to an endpoint that serves the content for YouTube.

Dynamic TLS Decryption Bypass

PolarProxy is designed to block TLS connections that it can’t decrypt, except for when the server’s domain name is explicitly marked for decryption bypass with the “--bypass” command line argument. However, as of recently PolarProxy also supports dynamic TLS decryption bypass using a form of fail-open mode. When this fail-open mode is enabled, PolarProxy attempts to intercept and decrypt proxied TLS traffic, but allows connections to bypass decryption if the same client-server pair has previously rejected PolarProxy’s certificate. This method is convenient when monitoring network traffic from applications that enforce certificate pinning or for some other reason can’t be configured to trust PolarProxy’s root CA – provided that it’s acceptable to let traffic that can’t be decrypted to pass through untouched rather than blocking it, of course.

The following command line option configures PolarProxy to allow new TLS connections to bypass decryption for one hour (3600 seconds) after previously having failed to decrypt traffic between the same client and server.

A simple way to verify this fail-open feature is to do a simple test with curl. It doesn’t matter if the client you’re testing on is Windows, Linux or macOS, since PolarProxy as well as curl is available for all three platforms.

Web browsers that don’t trust PolarProxy’s root CA will display a certificate warning the first time they visit a website that PolarProxy tries to decrypt traffic for.

But once the dynamic bypass has kicked in the user will no longer see a certificate warning when visiting the same website again, since traffic between that client and server is now end-to-end encrypted.

Handling of non-TLS traffic and Better Logging

Other new features in PolarProxy is the “--nontls” argument, which can be used to specify how to handle connections that doesn’t use TLS. The default action is to block non-TLS connections, but they can also be allowed to pass through (if the target host is known) or to forward the connection to a specific host and port. There is even a “--nontls encrypt” argument, which can be used to encrypt traffic that isn’t already TLS-encrypted before forwarding it to a specific host. This feature can be used as an alternative to stunnel to wrap traffic from applications that lack TLS support inside a TLS tunnel.

PolarProxy now also produces less output to stdout, unless -v is used, and error messages have been improved to be more specific and easier to understand.

Posted by Erik Hjelmvik on Tuesday, 28 February 2023 13:42:00 (UTC/GMT)

Tags: #PolarProxy​ #TLS​ #redirect​ #bypass​ #SNI​ #ASCII-art​

How to Identify IcedID Network Traffic

Brad Duncan published IcedID (Bokbot) from fake Microsoft Teams page earlier this week. In this video I take a closer look at the PCAP file in that blog post.

Note: This video was recorded in a Windows Sandbox to minimize the risk of infecting the host PC in case of accidental execution of a malicious payload from the network traffic.

As I have previously pointed out, IcedID sends beacons to the C2 server with a 5 minute interval. According to Kai Lu’s blog post A Deep Dive Into IcedID Malware: Part 2, this 5 minute interval is caused by a call to WaitForSingleObject with a millisecond timeout parameter of 0x493e0 (300,000), which is exactly 5 minutes.

The IcedID trojan uses a custom BackConnect protocol in order to interact with victim computers through VNC, a file manager or by establishing a reverse shell. There was no IcedID BackConnect traffic in this particular PCAP file though, but several other IcedID capture files published on malware-traffic-analysis.net do contain IcedID BackConnect traffic. For more information on this proprietary protocol, please see our blog post IcedID BackConnect Protocol.

IOC List

Fake Microsoft Teams download page

• URL: hxxp://microsofteamsus[.]top/en-us/teams/download-app/
• MD5: 5dae65273bf39f866a97684e8b4b1cd3
• SHA256: e365acb47c98a7761ad3012e793b6bcdea83317e9baabf225d51894cc8d9e800
• More info: urlscan.io

IcedID GzipLoader

• Filename: Setup_Win_13-02-2023_16-33-14.exe
• MD5: 7327fb493431fa390203c6003bd0512f
• SHA256: 68fcd0ef08f5710071023f45dfcbbd2f03fe02295156b4cbe711e26b38e21c00
• More info: Triage

IcedID payload disguised as fake gzip file

• URL: hxxp://alishabrindeader[.]com/
• MD5: 8e1e70f15a76c15cc9a5a7f37c283d11
• SHA256: 7eb6e8fdd19fc6b852713c19a879fe5d17e01dc0fec62fa9dec54a6bed1060e7
• More info: IcedID GZIPLOADER Analysis by Binary Defense

IcedID C2 communication

• IP and port: 192.3.76.227:443
• DNS: treylercompandium[.]com
• DNS: qonavlecher[.]com
• X.509 certificate SHA1: b523e3d33e7795de49268ce7744d7414aa37d1db
• X.509 certificate SHA256: f0416cff86ae1ecc1570cccb212f3eb0ac8068bcf9c0e3054883cbf71e0ab2fb
• JA3: a0e9f5d64349fb13191bc781f81f42e1
• JA3S: ec74a5c51106f0419184d0dd08fb05bc
• Beacon interval: 5 minutes
• More info: ThreatFox

Network Forensics Training

Check out our upcoming live network forensics classes for more hands-on network forensic analysis. Our current class material doesn’t include any IcedID traffic though, instead you’ll get to investigate C2 traffic from Cobalt Strike, TrickBot, njRAT, Meterpreter and a few others.

Posted by Erik Hjelmvik on Wednesday, 15 February 2023 10:52:00 (UTC/GMT)

Tags: #IcedID​ #CapLoader​ #Video​ #Periodicity​ #GzipLoader​ #a0e9f5d64349fb13191bc781f81f42e1​ #ec74a5c51106f0419184d0dd08fb05bc​