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PolarProxy 0.9 Released

PolarProxy 0.9

PolarProxy was previously designed to only run as a transparent TLS proxy. But due to popular demand we’ve now extended PolarProxy to also include a SOCKS proxy and a HTTP CONNECT proxy. PolarProxy automatically decrypts all proxied SSL and TLS traffic, regardless if the remote server is running on TCP 443 or some other port, as long as the traffic passes through PolarProxy. As from now we also release a Windows build of PolarProxy, alongside the Linux x64, ARM and ARM64 builds.

SOCKS Proxy

Use the command line argument “--socks [port]” to start PolarProxy’s SOCKS proxy server. This SOCKS proxy supports multiple versions of the SOCKS protocol, including SOCKS 4, SOCKS 4a, SOCKS 5 and SOCKS 5h.

As an example, the command below starts a SOCKS server on TCP port 1080 and passes a copy of the decrypted TLS traffic as a PCAP stream to tshark.

PolarProxy --socks 1080 -w - | tshark -r - -d tcp.port==443,http2
Note: The “-d tcp.port==443,http2” argument in the command above is used to tell tshark to parse traffic to port 443 as HTTP/2 instead of TLS. An alternative method would be to instead configure PolarProxy to output decrypted 443 traffic as if it was port 80, by supplying the “-p 443,80” argument to PolarProxy.

You can then use curl to run some HTTPS traffic through the SOCKS proxy:

curl --insecure --socks4 localhost https://www.netresec.com

After doing this you should see the decrypted HTTP/2 traffic in tshark’s output.

HTTP CONNECT Proxy

We’ve also added a HTTP proxy to PolarProxy 0.9, but it only supports the CONNECT request method. This means that normal unencrypted HTTP requests, like GET or POST requests, will be rejected by PolarProxy. Most web traffic is TLS encrypted nowadays anyway, so we don't consider this limitation to be a big issue.

The HTTP CONNECT proxy service is activated with the “--httpconnect” argument. Decrypted TLS traffic from PolarProxy’s HTTP CONNECT proxy can be forwarded to tshark just like in the SOCKS example, but the traffic from these proxies can also be accessed through PCAP-over-IP like this:

PolarProxy --httpconnect 8080 -p 443,80 --pcapoverip 57012

You can then connect to PolarProxy’s PCAP-over-IP service with NetworkMiner by clicking File, Receive PCAP over IP, select “Connect to IP/port”, enter “localhost” and click the “Start Receiving” button. You’ll now be able to see a real-time feed of all the traffic that PolarProxy decrypts. As an example, let’s download the PolarProxy logo over HTTPS to see if NetworkMiner can extract it from PolarProxy’s decrypted PCAP-over-IP stream:

curl --insecure --proxy localhost:8080 https://www.netresec.com/images/PolarProxy_313x313.png

The PolarProxy logo immediately shows up in NetworkMiner’s images tab:

NetworkMiner reading PCAP-over-IP from PolarProxy

Port-Independent TLS Protocol Detection

When PolarProxy is running as a transparent TLS proxy all incoming traffic can be expected to be TLS. But that’s not the case when, for example, PolarProxy is running as a SOCKS proxy. We have therefore added port-independent TLS protocol detection for proxied traffic, so that TLS traffic can be detected and decrypted even when it runs on other ports than the standard 443, 465, 853, 990, 993, 995 and 5061 ones.

There is one crucial limitation to the automatic SSL/TLS protocol detection though, it doesn’t support explicit TLS traffic that relies on opportunistic encryption features like STARTTLS, which bootstraps TLS into an already established application layer session.

Allow Non-TLS Traffic

SOCKS and HTTP CONNECT proxies can both be used to transport other protocols than TLS. PolarProxy blocks all non-TLS traffic by default, but this setting can be overridden with the “--allownontls” argument to allow any traffic to be proxied. The allow non-TLS override has no effect on PolarProxy’s transparent proxy though, because it will need to see a valid SNI field in order to know whereto the traffic should be forwarded.

Windows Build

There wasn’t much need for a Windows build of PolarProxy prior to the release of version 0.9, because the Windows firewall can’t be configured to redirect outgoing port 443 traffic to a local service. However, now that PolarProxy also includes SOCKS and HTTP CONNECT services, the situation is completely different. There are many ways to configure a Windows PC, as well as web browsers and other applications, to use a local proxy server.

You can use the Proxy settings window in Windows 10 and 11 to enable a local HTTP proxy like this:

Windows 10 Proxy Settings

Another option is to run “inetcpl.cpl” (Internet Options), open the “Connections” tab and click the “LAN settings” button to configure an HTTP proxy.

Windows Internet Options LAN Proxy Settings

You can, of course, also configure your browser to use a local SOCKS or HTTP proxy in Windows, just as you’d do on any other operating system.

But don’t forget to configure your OS and/or browser to trust your PolarProxy instance’s root CA certificate first, as explained in the “Trusting the PolarProxy root CA” section of our PolarProxy documentation.

The Windows version of PolarProxy is a .NET framework-dependent application, which requires the .NET 6 runtime to be installed. The PolarProxy releases for other platforms (Linux x64, ARM and ARM64) are all self-contained applications, which are published with the .NET runtime built-in.

Visit our PolarProxy page to download and install PolarProxy.

Posted by Erik Hjelmvik on Thursday, 13 January 2022 10:15:00 (UTC/GMT)

Tags: #PolarProxy#proxy#SOCKS#TLS#SSL#decrypt#Windows#PCAP-over-IP#pcapoverip

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Open .ETL Files with NetworkMiner and CapLoader

NetTrace.ETL in CapLoader 1.9.3 and NetworkMiner 2.7.2

Windows event tracing .etl files can now be read by NetworkMiner and CapLoader without having to first convert them to .pcap or .pcapng. The ETL support is included in NetworkMiner 2.7.2 and CapLoader 1.9.3, which were both released this morning.

What is an ETL Trace File?

ETL is short for Event Trace Log, which is ETW session data that has been logged to a file. You can, for example, extract EVTX logs from ETL files. But in this blog post we're gonna focus on network traffic that has been captured to an ETL file with a command like:

netsh trace start capture=yes report=no tracefile=packets.etl
...wait while packets are being captured...
netsh trace stop

Pro-tip: You can specify a capture NIC explicitly with "CaptureInterface=<GUID>"

NetworkMiner and CapLoader can also read packets in Pktmon ETL files, which actually are different from those created with netsh. Capturing packets to an ETL file with Pktmon is very simple:

pktmon start --capture --pkt-size 0 -f packets.etl
...wait while packets are being captured...
pktmon stop

Pro-tip: You can specify capture filters with "pktmon filter add"

You can also capture packets to ETL files with PowerShell:

New-NetEventSession -Name sniffer -LocalFilePath C:\packets.etl
Add-NetEventPacketCaptureProvider -SessionName sniffer -TruncationLength 2000
Start-NetEventSession -Name sniffer
...wait while packets are being captured...
Stop-NetEventSession -Name sniffer
Remove-NetEventSession -Name sniffer

Pro-tip: You capture packets on a remote PC by specifying a CimSession

Advantages

The built-in support for ETL files in NetworkMiner and CapLoader makes it easy to work with ETL files. Not only will you no longer need to go through the extra step of converting the ETL file to PCAP using etl2pcapng or Microsoft Message Analyzer (which was retired in 2019), the analysis will also be faster because both CapLoader and NetworkMiner read ETL files faster compared to etl2pcapng and MMA.

Limitations

The primary limitation with NetworkMiner and CapLoader's ETL support is that it only works in Windows. This means that you will not be able to open ETL files when running NetworkMiner in Linux or macOS.

Another limitation is that both NetworkMiner and CapLoader might fail to parse logged packets if the event trace was created on an OS version with an event manifest that is incompatible with the OS version on which the ETL file is opened.

Under the Hood

Both NetworkMiner and CapLoader leverage Windows specific API calls to read packets from ETL files. An ETL file opened in CapLoader first get converted to PcapNG, then CapLoader parses that PcapNG file. NetworkMiner, on the other hand, parses the packets in the ETL file directly to extract artifacts like files, images and parameters. NetworkMiner's approach is both simpler and quicker, but by converting the ETL file to PcapNG CapLoader can utilize its packet indexing feature to rapidly extract any subset of the captured traffic upon request by the user.

CapLoader's approach is also useful for users who are wondering how to open ETL files in Wireshark, since the packets from an ETL file can be opened in Wireshark by dragging the PcapNG file from the CapLoader GUI onto Wireshark.

Drag-and-drop NetTrace.pcapng from CapLoader to Wireshark
Image: NetTrace.etl converted to PcapNG in CapLoader can be drag-and-dropped onto Wireshark.

Additional Updates in NetworkMiner

The ETL support is not the only new feature in NetworkMiner 2.7.2 though. We have also added support for the ERSPAN protocol. The FTP parser has also been improved to support additional commands, such as AUTH (RFC2228).

We've also added a useful little feature to the context menu of the Parameter's tab, which allows users to send extracted parameters to CyberChef (on gchq.github.io) for decoding.

Submit Parameter value from NetworkMiner to CyberChef
Image: Right-clicking a parameter brings up a context menu with "Submit to CyberChef" option.

Additional Updates in CapLoader

The only major improvement in CapLoader 1.9.3, apart from the built-in ETL-to-PcapNG converter, is that the protocol identification speed and precision has been improved. We've also separated the identification of SSL (version 2.0 to 3.0) and TLS (SSL 3.1 and later) as two separate protocols in this version, whereas they previously both were fingerprinted as "SSL".

Credits

We'd like to thank Dick Svensson and Glenn Larsson for their input on reading ETL files. We also want to thank Markus Schewe for recommending us to add ERSPAN support to NetworkMiner!

Posted by Erik Hjelmvik on Tuesday, 02 November 2021 07:15:00 (UTC/GMT)

Tags: #PowerShell#CapLoader#NetworkMiner#PcapNG#Windows#Wireshark#PCAP#CyberChef

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How the SolarWinds Hack (almost) went Undetected

My lightning talk from the SEC-T 0x0D conference has now been published on YouTube. This 13 minute talk covers tactics and techniques that the SolarWinds hackers used in order to avoid being detected.

Video: Hiding in Plain Sight, How the SolarWinds Hack went Undetected

Some of these tactics included using DNS based command-and-control (C2) that mimicked Amazon AWS DNS traffic, blending in with SolarWind’s legitimate source code and handpicking only a small number of targets.

One thing I forgot to mention in my SEC-T talk though, was the speed at which the attackers were working to analyze incoming data from the trojanized installs and selecting organizations to target for stage two operations.

SolarWinds Hack Timeline

For example, just during June 2020 the attackers got more than 1300 new organizations that started beaconing in using the DNS-based C2. The beaconed data only included the organizations’ Active Directory domain name and a list of installed security applications. Based on this information the attackers had to decide whether or not they wanted to target the organization. We have previously estimated that less than 1% of the organizations were targeted, while the malicious backdoor was disabled for all the other 99% who had installed the trojanized SolarWinds Orion update.

SolarWinds C2 IP addresses

The attackers typically decided whether or not to target an organization within one week from when they started beaconing. This means that the attackers probably had several hundred organizations in queue for a targeting decision on any given week between April and August 2020. That's a significant workload!

Posted by Erik Hjelmvik on Monday, 18 October 2021 10:30:00 (UTC/GMT)

Tags: #SolarWinds#SEC-T#video#backdoor#SUNBURST#Solorigate#STAGE2#Stage 2#DNS#C2#ASCII-art

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Start Menu Search Video

In this video I demonstrate that text typed into the Windows 10 start menu gets sent to Microsoft and how that traffic can be intercepted, decrypted and parsed.

What Was Sent?

The XML files shown in the video were sent by Cortana's "SmartSearch" app to https://www.bing.com/threshold/xls.aspx in HTTP/2 POST requests. As shown in the video, the POST'ed keystrokes can be found inside requestInfo XML tags that have a "RawQuery" key.

The following tcpdump and grep commands can be used to list the RawQuery data sent to Bing in these HTTP/2 requests:

tcpdump -A -r proxy-210927-134557.pcap | grep -a -o 'key="RawQuery" value="[^"]*"'

Running that command on the PolarProxy PCAP file from the video gives the following output:

key="RawQuery" value="n"
key="RawQuery" value="no"
key="RawQuery" value="not"
key="RawQuery" value="note"
key="RawQuery" value="notep"
key="RawQuery" value="notepa"
key="RawQuery" value="notepad"
key="RawQuery" value="s"
key="RawQuery" value="se"
key="RawQuery" value="sea"
key="RawQuery" value="sear"
key="RawQuery" value="searc"
key="RawQuery" value="search"
key="RawQuery" value="search .."
key="RawQuery" value="search ..e"
key="RawQuery" value="search ..er"
key="RawQuery" value="search ..e"
key="RawQuery" value="search .."
key="RawQuery" value="search"
key="RawQuery" value="search p"
key="RawQuery" value="search per"
key="RawQuery" value="search perm"
key="RawQuery" value="search permi"
key="RawQuery" value="p"
key="RawQuery" value="pr"
key="RawQuery" value="pri"
key="RawQuery" value="priv"
key="RawQuery" value="priva"
key="RawQuery" value="privac"
key="RawQuery" value="privacy"

The same data also gets sent in the query string variable "qry" of GET requests for https://www.bing.com/AS/API/WindowsCortanaPane/V2/Suggestions, as shown in this NetworkMiner screenshot.

Parameters tab in NetworkMiner
Image: NetworkMiner's Parameters tab with filter "qry" on "Parameter name" column

How to Intercept, Decrypt and Decode HTTPS Traffic

The following section presents the technical details regarding my setup, so that others can reproduce and verify these findings.

My first step was to install PolarProxy on a Linux machine on the local network. PolarProxy is a TLS proxy, which can intercept and decrypt TLS traffic. This TLS proxy is primarily designed to decrypt traffic from malware and hackers, but can also be used to decrypt legitimate traffic when needed.

PolarProxy was configured to listen for incoming TLS connections on TCP port 443 and output PCAP data with the decrypted traffic as if it had been transmitted over TCP 80. The decrypted traffic was accessible as a real-time stream through a PCAP-over-IP service running on port 57012. Here's the full command that was used to start PolarProxy:

sudo ./PolarProxy -p 443,80 --pcapoverip 0.0.0.0:57012 --certhttp 10080

In the video I showed the Windows 10 client's modified hosts file, which included an entry for www.bing.com pointing to the PolarProxy machine. What was not shown in the video though, is that PolarProxy's own CA certificate had been added to the Win10 machine's list of trusted root CA's, as explained in the "Trusting the PolarProxy root CA" section of the PolarProxy installation instructions. With these two changes in place all HTTPS requests for www.bing.com from the Win10 PC got diverted through the PolarProxy TLS inspection service, which then decrypted and re-encrypted the traffic before forwarding it to Bing.

The decrypted Bing requests could be accessed either locally on the Linux machine, or remotely using the PCAP-over-IP service on TCP port 57012. I used NetworkMiner to read the live PCAP stream with decrypted traffic from port 57012 and extract all files being sent and received in real-time.

Is it Possible to Disable the Cortana Search?

When Ars Technica reporters asked Microsoft back in 2015 if there was any way to disable this communication, Microsoft replied with the following statement:

As part of delivering Windows 10 as a service, updates may be delivered to provide ongoing new features to Bing search, such as new visual layouts, styles and search code. No query or search usage data is sent to Microsoft, in accordance with the customer's chosen privacy settings.

There are plenty of how-to guides online with instructions on how the Cortana search feature can be disabled. Most of these guides suggest disabling the AllowCortana setting in group policies or in the registry. We've tried several of the settings suggested in these how-to guides, but none of them seem to prevent Windows from sending keystrokes to Bing.

If you know how to successfully disable Cortana's Bing searches, then please feel free to reach out to us so that we can update this blog post.

UPDATE 210928 - How to Actually Disable Cortana Search

Twitter user @GeorgeProfonde3 reached out to suggest a fix that might prevent the start menu from sending data to Bing. We have now verified this fix and we're happy to announce that it works (at least for us).

  1. Start regedit.exe
  2. Open the following registry key:
    HKEY_CURRENT_USER\SOFTWARE\Microsoft\Windows\CurrentVersion\Search
  3. Ensure that the value for CortanaConsent is set to 0
  4. Create a new DWORD registry entry called "BingSearchEnabled" with value 0

You should no longer see any connections to www.bing.com when interacting with the start menu after implementing this fix.

UPDATE 211015 - Another way to Disable Cortana Search

You may need to use a different method to disable the start meny search, depending on your Windows version and build. Kimberly (@StopMalvertisin) suggested the following method, which seems to work on Windows 11:

  1. Start regedit.exe
  2. Create a registry key for:
    HKEY_CURRENT_USER\SOFTWARE\Policies\Microsoft\Windows\Explorer
  3. Create a new DWORD registry entry called "DisableSearchBoxSuggestions" with value 1

Disabling Start Menu Search from Group Policy

There are also a few different methods for disabling start menu searches using GPO. However, please note that your success will vary depending on your Windows version and build.

GPO Method #1

  1. Start gpedit.msc
  2. Open the following branch:
    User configuration\Administrative templates\Windows components\File Explorer
  3. Enable the following group policy:
    "Turn off display of recent search entries in the File Explorer search box"

GPO Method #2

  • Start gpedit.msc
  • Open the following branch:
    User Configuration\Administrative Templates\Start Menu and Taskbar
  • Enable the following group policy: "Do not search communications"

Posted by Erik Hjelmvik on Tuesday, 28 September 2021 08:24:00 (UTC/GMT)

Tags: #PCAP#NetworkMiner#PolarProxy#Microsoft#video#videotutorial#pcapoverip#PCAP-over-IP#HTTP/2#http2

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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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