NETRESEC Network Security Blog - Tag : SOCKS


TorPCAP - Tor Network Forensics

PcapTor

Unencrypted network traffic, destined for the Tor network, is sent between localhost TCP sockets on computers running Tor clients, such as the Tor Browser. In this blog post I show how anonymous Tor browsing can be visualized, by loading a PCAP file with localhost traffic into NetworkMiner. We call this technique TorPCAP.

Tor is a secure platform that enables users to browse the web anonymously. The Tor Project website describes the tool as:

“Tor is free software and an open network that helps you defend against traffic analysis”

It is also possible to host anonymous “onion services” on the Dark Web using Tor:

“Tor makes it possible for users to hide their locations while offering various kinds of services, such as web publishing or an instant messaging server. Using Tor "rendezvous points," other Tor users can connect to these onion services, formerly known as hidden services, each without knowing the other's network identity.”

Capturing Tor Traffic Before it gets Encrypted

Tor installations include a SOCKS proxy listening on TCP port 9150 on localhost (127.0.0.1). This local SOCKS proxy is used by the Tor Browser, which connects to the proxy in order to have its traffic encrypted and forwarded to the Tor network. This means that by sniffing traffic on localhost it’s actually possible to create a solid forensic trail of all traffic a PC sends to and from the Tor network.

Tor Browser and SOCKS

You can use tcpdump to capture the localhost traffic on PCs running the Tails OS or Tor Browser in MacOS or Linux. If you’re running the Tor Browser in Windows, then we recommend using RawCap to sniff the localhost traffic (RawCap is a portable standalone tool that doesn’t need WinPcap or NDIS drivers to work).

In order to make sense of the captured traffic you need a tool that can parse the SOCKS protocol (RFC 1928). NetworkMiner includes a SOCKS parser since version 2.1, which can be used to extract and reassemble data going to and from the Tor network.


   Image Credit: Ken Edge    Eldon by @kenedgeiscool

Demo: Analysing TorPCAP Network Traffic

A user, let’s call him “Eldon”, used Tor for some dark-web activity on November 30, 2018. Eldon was using the Tor Browser on a Windows PC and RawCap was used to capture the localhost network traffic from Eldon’s computer. A PCAP file with the captured packets from Eldon’s PC can be accessed here. Please feel free to open this capture file with NetworkMiner, in order to follow along in this analysis.


File   : rawcap-localhost-tor.pcap
Size   : 1.47 MB
SHA256 : 9134FA542B388498C2A58A2E1424FCD4AF466CE7117DBE9AAFD0A031CC8209B8


The “Files” tab in NetworkMiner contains a list of all files that have been reassembled from the analyzed PCAP file. This file listing reveals that Eldon used the “not Evil” search engine (hss3uro2hsxfogfq[.]onion) to search for “buy fake passports” in frame 1136.

NetworkMiner's Files tab with not Evil search

The search result page from not Evil has been reassemled by NetworkMiner as “index.php.CB66877E.html”. By opening this HTML document in a browser we can see which search results Eldon got (no Internet connection is needed to open the reassembled html).

not Evil search in Tor

The “Browsers” tab in NetworkMiner Professional shows that Eldon followed the link for entry #2 in his search results (BUY FAKE PASSPORTS [...]), leading him to the “fakeimz[...].onion” website.

HTML document in Edge reassembled by NetworkMiner

Eldon then proceeded to list the available passports (see the reassembled file “novelty_fake_id_samples.shtml” in frame 1837) and chose the UK passport (“pp-uk-open-big.jpg”).

novelty_fake_id_samples.shtml NetworkMiner Professional Images tab with pp-uk-open-big.jpg

As Eldon proceeded he got a price list for the fake passports offered at this site (“novelty_fake_id_pricing.shtml”), but we don’t see any evidence of him actually completing a purchase of a fake UK passport.

HTML file reassembled by NetworkMiner opened in Edge browser

If we go back to the Images tab in NetworkMiner, and scroll a bit further down we see a picture of a gun. Let’s see where it comes from.

NetworkMiner Images tab with gun pic

It turns out Eldon also searched for “buy guns for bitcoin UK”. You can list all search engine queries by looking for entries in the “Parameters” tab with parameter name “q”. This technique is applicable for the “not Evil” search engine as well as most clearnet search engines, like Google, Bing, Yahoo! and DuckDuckGo (disregarding the fact that they use TLS).

NetworkMiner Parameters tab with web searches

The Browsers tab shows us that Eldon clicked on a link to the “UK Guns and Ammo Store” (tuu66[...].onion).

not Evil search in NetworkMiner Professional Browsers tab

This website has also been passively reassembled by NetworkMiner and can be opened offline in a browser (see “index[2].html”).

UK Guns and Ammo Store (dark web)

The Credentials tab in NetworkMiner shows the username and password used by Eldon to log into the website:

Credentials tab in NetworkMiner Professional 2.3.1 showing username and password sent over Tor to an onion service

After logging in, Eldon puts two items in his shopping cart (see “cart.php[1].html”), but gets a message saying “Not enough balance for this order” when clicking the “Continue to Checkout” link. It seems Eldon’s account at the dark-web weapons store doesn’t have any Bitcoins (see “wallet.php.html”)

UK Guns and Ammo Store - Shopping Cart (dark web) UK Guns and Ammo Store - Bitcoin Wallet (dark web)

Side Note - Web Trackers and Tor

It is considered bad practice to use clear-net tracking services, like Google Analytics, to track users visiting an onion service. However, we noticed that the fake passports website uses a Google Analytics script with tracking ID “UA-19359933-1”.

Dark Web HTML with Googla Analytics ID UA-19359933-1

Googling this ID led us to this very similar website:
hxxp://www.buypassportsfake[.]cc

hxxp://www.buypassportsfake[.]cc

Posted by Leon Kowalski on Wednesday, 12 December 2018 09:33:00 (UTC/GMT)

Tags: #PCAP #NetworkMiner #RawCap #SOCKS

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NetworkMiner 2.2 Released

NetworkMiner 2.2 = Harder Better Faster Stronger

NetworkMiner 2.2 is faster, better and stronger than ever before! The PCAP parsing speed has more than doubled and even more details are now extracted from analyzed packet capture files.

The improved parsing speed of NetworkMiner 2.2 can be enjoyed regardless if NetworkMiner is run in Windows or Linux, additionally the user interface is more responsive and flickers way less when capture files are being loaded.

User Interface Improvements

The keyword filter available in the Files, Messages, Sessions, DNS and Parameters tabs has been improved so that the rows now can be filtered on a single column of choice by selecting the desired column in a drop-down list. There is also an “Any column” option, which can be used to search for the keyword in all columns.

Keyword drop-down in NetworkMiner's Parameters tab

The Messages tab has also received an additional feature, which allows the filter keyword to be matched against the text in the message body as well as email headers when the “Any column” option is selected. This allows for an efficient analysis of messages (such as emails sent/received through SMTP, POP3 and IMAP as well as IRC messages and some HTTP based messaging platforms), since the messages can be filtered just like in a normal e-mail client.

We have also given up on using local timestamp formats; timestamps are now instead shown using the yyyy-MM-dd HH:mm:ss format with time zone explicitly stated.

Protocol Parsers

NetworkMiner 2.2 comes with a parser for the Remote Desktop Protocol (RDP), which rides on top of COTP and TPKT. The RDP parser is primarily used in order to extract usernames from RDP cookies and show them on the Credentials tab. This new version also comes with better extraction of SMB1 and SMB2 details, such as NTLM SSP usernames.

RDP Cookies extracted with NetworkMiner 2.2

One big change that has been made behind the scenes of NetworkMiner is the move from .NET Framework 2.0 to version 4.0. This move doesn’t require any special measures to be taken for most Microsoft Windows users since the 4.0 Framework is typically already installed on these machines. If you’re running NetworkMiner in Linux, however, you might wanna check out our updated blog post on how to install NetworkMiner in Linux.

We have also added an automatic check for new versions of NetworkMiner, which runs every time the tool is started. This update check can be disabled by adding a --noupdatecheck switch to the command line when starting NetworkMiner.

NetworkMiner.exe --noupdatecheck capturefile.pcap

NetworkMiner Professional

Even though NetworkMiner 2.2 now uses ISO-like time representations NetworkMiner still has to decide which time zone to use for the timestamps. The default decision has always been to use the same time zone as the local machine, but NetworkMiner Professional now additionally comes with an option that allows the user to select whether to use UTC (as nature intended), the local time zone or some other custom time zone for displaying timestamps. The time zone setting can be found in the “Tools > Settings” menu.

UPDATE: With the release of NetworkMiner 2.3 the default time zone is now UTC unless the user has specifically selected a different time zone.

The Port-Independent-Protocol-Detection (PIPI) feature in NetworkMiner Pro has been improved for more reliable identification of HTTP, SSH, SOCKS, FTP and SSL sessions running on non-standard port numbers.

CASE / JSON-LD Export

We are happy to announce that the professional edition of NetworkMiner 2.2 now has support for exporting extracted details using the Cyber-investigation Analysis Standard Expression (CASE) format, which is a JSON-LD format for digital forensics data. The CASE export is also available in the command line tool NetworkMinerCLI.

We would like to thank Europol for recommending us to implement the CASE export format in their effort to adopt CASE as a standard digital forensic format. Several other companies in the digital forensics field are currently looking into implementing CASE in their tools, including AccessData, Cellebrite, Guidance, Volatility and XRY. We believe the CASE format will become a popular format for exchanging digital forensic data between tools for digital forensics, log correlation and SIEM solutions.

We will, however, still continue supporting and maintaining the CSV and XML export formats in NetworkMiner Professional and NetworkMinerCLI alongside the new CASE format.

Credits

I would like to thank Sebastian Gebhard and Clinton Page for reporting bugs in the Credentials tab and TFTP parsing code that now have been fixed. I would also like to thank Jeff Carrell for providing a capture file that has been used to debug an issue in NetworkMiner’s OpenFlow parser. There are also a couple of users who have suggested new features that have made it into this release of NetworkMiner. Marc Lindike suggested the powerful deep search of extracted messages and Niclas Hirschfeld proposed a new option in the PCAP-over-IP functionality that allows NetworkMiner to receive PCAP data via a remote netcat listener.

Upgrading to Version 2.2

Users who have purchased a license for NetworkMiner Professional 2.x can download a free update to version 2.2 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.

Posted by Erik Hjelmvik on Tuesday, 22 August 2017 11:37:00 (UTC/GMT)

Tags: #pcap #CASE #PIPI #HTTP #SOCKS #SSL #port #forensics

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CapLoader 1.5 Released

CapLoader 1.5 Logo

We are today happy to announce the release of CapLoader 1.5. This new version of CapLoader parses pcap and pcap-ng files even faster than before and comes with new features, such as a built-in TCP stream reassembly engine, as well as support for Linux and macOS.

Support for ICMP Flows

CapLoader is designed to group packets together that belong to the same bi-directional flow, i.e. all UDP, TCP and SCTP packets with the same 5-tuple (regardless of direction) are considered being part of the same flow.

5-tuple
/fʌɪv ˈtjuːp(ə)l/
noun

A combination of source IP, destination IP, source port, destination port and transport protocol (TCP/UDP/SCTP) used to uniquely identify a flow or layer 4 session in computer networking.

The flow concept in CapLoader 1.5 has been extended to also include ICMP. Since there are no port numbers in the ICMP protocol CapLoader sets the source and destination port of ICMP flows to 0. The addition of ICMP in CapLoader also allows input filters and display filters like “icmp” to be leveraged.

Flows tab in CapLoader 1.5 with display filter BPF 'icmp'
Image: CapLoader 1.5 showing only ICMP flows due to display filter 'icmp'.

TCP Stream Reassembly

One of the foundations for making CapLoader a super fast tool for reading and filtering PCAP files is that it doesn’t attempt to reassemble TCP streams. This means that CapLoader’s Transcript view will show out-of-order segments in the order they were received and retransmitted segments will be displayed twice.

The basic concept has been to let other tools do the TCP reassembly, for example by exporting a PCAP for a flow from CapLoader to Wireshark or NetworkMiner.

The steps required to reassemble a TCP stream to disk with Wireshark are:

  1. Right-click a TCP packet in the TCP session of interest.
  2. Select “Follow > TCP Stream”.
  3. Choose direction in the first drop-down-list (client-to-server or server-to-client).
  4. Change format from “ASCII” to “Raw” in the next drop-down-menu.
  5. Press the “Save as...” button to save the reassembled TCP stream to disk.

Follow TCP Stream window in Wireshark

Unfortunately Wireshark fails to properly reassemble some TCP streams. As an example the current stable release of Wireshark (version 2.2.5) shows duplicate data in “Follow TCP Stream” when there are retransmissions with partially overlapping segments. We have also noticed some additional  bugs related to TCP stream reassembly in other recent releases of Wireshark. However, we’d like to stress that Wireshark does perform a correct reassembly of most TCP streams; it is only in some specific situations that Wireshark produces a broken reassembly. Unfortunately a minor bug like this can cause serious consequences, for example when the TCP stream is analyzed as part of a digital forensics investigation or when the extracted data is being used as input for further processing. We have therefore decided to include a TCP stream reassembly engine in CapLoader 1.5. The steps required to reassemble a TCP stream in CapLoader are:

  1. Double click a TCP flow of interest in the “Flows” tab to open a flow transcript.
  2. Click the “Save Client Byte Stream” or “Save Server Byte Stream” button to save the data stream for the desired direction to disk.

Transcript window in CapLoader 1-5

Extracting TCP streams from PCAP files this way not only ensures that the data stream is correctly reassembled, it is also both faster and simpler than having to pivot through Wireshark’s Follow TCP Stream feature.

PCAP Icon Context Menu

CapLoader 1.5 PCAP icon Save As...

The PCAP icon in CapLoader is designed to allow easy drag-and-drop operations in order to open a set of selected flows in an external packet analysis tool, such as Wireshark or NetworkMiner. Right-clicking this PCAP icon will bring up a context menu, which can be used to open a PCAP with the selected flows in an external tool or copy the PCAP to the clipboard. This context menu has been extended in CapLoader 1.5 to also include a “Save As” option. Previous versions of CapLoader required the user to drag-and-drop from the PCAP icon to a folder in order to save filtered PCAP data to disk.

Faster Parsing with Protocol Identification

CapLoader can identify over 100 different application layer protocols, including HTTP, SSL, SSH, RTP, RTCP and SOCKS, without relying on port numbers. The protocol identification has previously slowed down the analysis quite a bit, which has caused many users to disable this powerful feature. This new release of of CapLoader comes with an improved implementation of the port-independent protocol identification feature, which enables PCAP files to be loaded twice as fast as before with the “Identify protocols” feature enabled.

Works in Linux and macOS

One major improvement in CapLoader 1.5 is that this release is compatible with the Mono framework, which makes CapLoader platform independent. This means that you can now run CapLoader on your Mac or Linux machine if you have Mono installed. Please refer to our previous blog posts about how to run NetworkMiner in various flavors of Linux and macOS to find out how to install Mono on your computer. You will, however, notice a performance hit when running CapLoader under Mono instead of using Windows since the Mono framework isn't yet as fast as Microsoft's .NET Framework.

CapLoader 1.5 running in Linux with Mono
Image: CapLoader 1.5 running in Linux (Xubuntu).

Credits

We’d like to thank Sooraj for reporting a bug in the “Open With” context menu of CapLoader’s PCAP icon. This bug has been fixed in CapLoader 1.5 and Sooraj has been awarded an official “PCAP or it didn’t happen” t-shirt for reporting the bug.

PCAP or it didn't happen t-shirt
Image: PCAP or it didn't happen t-shirt

Have a look at our Bug Bounty Program if you also wanna get a PCAP t-shirt!

Downloading CapLoader 1.5

Everything mentioned in this blog post, except for the protocol identification feature, is available in our free trial version of CapLoader. To try it out, simply grab a copy here:
https://www.netresec.com/?page=CapLoader#trial (no registration needed)

All paying customers with an older version of CapLoader can download a free update to version 1.5 from our customer portal.

Posted by Erik Hjelmvik on Tuesday, 07 March 2017 09:11:00 (UTC/GMT)

Tags: #CapLoader #PCAP #pcap-ng #Follow TCP Stream #Wireshark #Linux #Mac #RTP #SOCKS #Mono #Flow

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NetworkMiner 2.1 Released

NetworkMiner 2.1 Logo

We are releasing a new version of NetworkMiner today. The latest and greatest version of NetworkMiner is now 2.1.

Yay! /throws confetti in the air


Better Email Parsing

I have spent some time during 2016 talking to digital forensics experts at various law enforcement agencies. I learned that from time to time criminals still fail to use encryption when reading their email. This new release of NetworkMiner therefore comes with parsers for POP3 and IMAP as well as an improved SMTP parser. These are the de facto protocols used for sending and receiving emails, and have been so since way back in the 90’s.

Messages tab in NetworkMiner 2.1 showing extracted emails
Messages tab in NetworkMiner 2.1 showing extracted emails

Not only does NetworkMiner show the contents of emails within the tool, it also extracts all attachments to disk and even saves each email as an .eml file that can be opened in an external email reader in order to view it as the suspect would.

Extracted email Get_free_s.eml opened in Mozilla Thunderbird
Extracted email ”Get_free_s.eml” opened in Mozilla Thunderbird

Encapsulation Protocols

There are several protocols that can be used to provide logical separation of network traffic, in order to avoid using multiple physical networks to keep various network segments, security domains or users apart. Some of these techniques for logical separation rely on tagging or labeling, while others are tunneling the encapsulated traffic. Nevertheless, it’s all pretty much the same thing; an encapsulation protocol is used in order to wrap protocol X inside protocol Y, usually while adding some metadata in the process.

NetworkMiner has been able to parse the classic encapsulation protocols 802.1Q, GRE and PPPoE since 2011, but we now see an increased use of protocols that provide logical separation for virtualization and cloud computing environments. We have therefore added parsers in NetworkMiner 2.1 for VXLAN and OpenFlow, which are the two most widely used protocols for logical separation of traffic in virtualized environments. We have also added decapsulation of MPLS and EoMPLS (Ethernet-over-MPLS) to NetworkMiner 2.1.

Encapsulation examples for MPLS GRE and VXLAN

The new release additionally comes with support for the SOCKS protocol, which is an old school encapsulation protocol used by administrators as well as hackers in order to bypass firewalls or provide anonymous Internet access. The SOCKS parser in NetworkMiner can even be used to read network traffic from Tor in cleartext before it enters the Tor network. However, in order to capture Tor’s SOCKS traffic you’ll have to sniff traffic from the Tor client’s localhost interface on TCP port 9150.

PacketCache Logo

PacketCache

NetworkMiner 2.1 can read packets directly from a local PacketCache service by clicking ”File > Read from PacketCache”. This eliminates the need to run a PowerShell script in order to dump a PCAP file with packets recently captured by PacketCache.

HTTP Partial Content / Range Requests

Byte serving is a feature in HTTP that makes it possible to retrieve only a segment of a file, rather than the complete file, by using the “Range” HTTP header. This feature is often used by BITS in order to download updates for Windows. But we have also seen malware use byte serving, for example malware droppers that attempt to download malicious payloads in a stealthy manner. See Ursnif and Dridex for examples of malware that utilize this technique.

NetworkMiner has previously only reassembled the individual segments of a partial content download. But as of version 2.1 NetworkMiner has the ability to piece together the respective parts into a complete file.

SSL/TLS and X.509 Certificates

NetworkMiner has been able to extract X.509 certificates to disk for many years now, simply by opening a PCAP file with SSL traffic. However, in the 2.1 release we’ve added support for parsing out the SSL details also from FTP’s “AUTH TLS” (a.k.a explicit TLS or explicit SSL) and STARTTLS in SMTP.

NetworkMiner now also extracts details from the SSL handshake and X.509 certificate to the Parameters tab, such as the requested SNI hostname and the Subject CN from the certificate.

SSL and certificate information extracted by NetworkMiner from PCAP
SSL handshake details and certificate info passively extracted from captured HTTPS session to mega.co.nz

NetworkMiner Professional

The new features mentioned so far are all part of the free open source version of NetworkMiner. But we have also added a few additional features to the Professional edition of NetworkMiner as part of the 2.1 release.

The “Browsers” tab of NetworkMiner Professional has been extended with a feature for tracking online ads and web trackers. We are using EasyList and EasyPrivacy from easylist.to in order to provide an up-to-date tracking of ads and trackers. HTTP requests related to ads are colored red, while web tracker requests are blue. These colors also apply to the Files tab and can be modified in the Settings menu (Tools > Settings).

NetworkMiner Professional 2.1 showing Advertisments (red) and Trackers (blue)
NetworkMiner Professional 2.1 showing advertisments (red) and Internet trackers (blue).

The reason why NetworkMiner Pro now tracks ads and trackers is because these types of requests can make up almost half of the HTTP requests that a normal user makes while surfing the web today. Doing forensics on network traffic from a suspect criminal can be a very time consuming task, we therefore hope that being able to differentiate between what traffic that is initiated by the user rather than being triggered by an online advertisement service or internet tracker can save time for investigators.

The RIPE database previously contained a bug that prevented NetworkMiner Professional from properly leveraging netname info from RIPE. This bug has now been fixed, so that the Host Details can be enriched with details from RIPE for IP addresses in Europe. To enable the RIPE database you’ll first have to download the raw data by clicking Tools > Download RIPE DB.

Host Details with RIPE netname Host Details enriched with RIPE description and netname

We have also extended the exported details about the hosts in the CSV and XML files from NetworkMiner Professional and the command line tool NetworkMinerCLI. The exported information now contains details such as IP Time-to-Live and open ports.

Upgrading to version 2.1

Users who have purchased a license for NetworkMiner Professional 2.0 can download a free update to version 2.1 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.

Credits

There are several persons I would like to thank for contributing with feature requests and bug reports that have been used to improve NetworkMiner. I would like to thank Dietrich Hasselhorn, Christian Reusch, Jasper Bongertz, Eddi Blenkers and Daniel Spiekermann for their feedback that have helped improve the SMB, SMB2 and HTTP parsers as well as implementing various encapsulation protocols. I would also like to thank several investigators at the Swedish, German and Dutch police as well as EUROPOL for the valuable feedback provided by them.

Posted by Erik Hjelmvik on Wednesday, 11 January 2017 14:30:00 (UTC/GMT)

Tags: #NetworkMiner #SMTP #IMAP #X.509 #PCAP

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book

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)