NETRESEC Network Security Blog - Tag : DGA


CapLoader 1.8 Released

CapLoader 1.8

We are happy to announce the release of CapLoader 1.8 today!

CapLoader is primarily used to filter, slice and dice large PCAP datasets into smaller ones. This new version contains several new features that improves this filtering functionality even further. To start with, the “Keyword Filter” can now be used to filter the rows in the Flows, Services or Hosts tabs using regular expressions. This enables the use of matching expressions like this:

  • amazon|akamai|cdn
    Show only rows containing any of the strings “amazon” “akamai” or “cdn”.
  • microsoft\.com\b|windowsupdate\.com\b
    Show only servers with domain names ending in “microsoft.com” or “windowsupdate.com”.
  • ^SMB2?$
    Show only SMB and SMB2 flows.
  • \d{1,3}\.\d{1,3}\.\d{1,3}\.255$
    Show only IPv4 address ending with “.255”.

For a reference on the full regular expression syntax available in CapLoader, please see Microsoft’s regex “Quick Reference”.

One popular workflow supported by CapLoader is to divide all flows (or hosts) into two separate datasets, for example one “normal” and one “malicious” set. The user can move rows between these two sets, where only one set is visible while the rows in the other set are hidden. To switch which dataset that is visible versus hidden the user needs to click the [Invert Hiding] button (or use the [Ctrl]+[Tab] key combination). With this new release we’ve also made the “Invert Hiding” functionality available by clicking the purple bar, which shows the number of rows present in the currently viewed set.

CapLoader Invert Hiding GIF

Readers with a keen eye might also notice that the purple bar charts are now also accompanied by a number, indicating how many rows that are visible after each filter is applied. The available filters are: Set Selection, BPF and Keyword Filter.

NetFlow + DNS = Great Success!

CapLoader’s main view presents the contents of the loaded PCAP files as a list of netflow records. Since the full PCAP is available, CapLoader also parses the DNS packets in the capture files in order to enrich the netflow view with hostnames. Recently PaC shared a great idea with us, why not show how many failed DNS lookups each client does? This would enable generic detection of DGA botnets without using blacklists. I’m happy to announce that this great idea made it directly into this new release! The rightmost column in CapLoader’s hosts tab, called “DNS_Fails”, shows how many percent of a client’s DNS requests that have resulted in an NXRESPONSE or SRVFAIL response.

CapLoader 1.8

Two packet capture files are loaded into CapLoader in the screenshot above; one PCAP file from a PC infected with the Shifu malware and one PCAP file with “normal traffic” (thanks @StratosphereIPS for sharing these capture files). As you can see, one of the clients (10.0.2.107) has a really high DNS failure ratio (99.81%). Unsurprisingly, this is also the host that was infected with the Shifu, which uses a domain generation algorithm (DGA) to locate its C2 servers.

Apart from parsing A and CNAME records from DNS responses CapLoader now also parses AAAA DNS records (IPv6 addresses). This enables CapLoader to map public domain names to hosts with IPv6 addresses.

Additional Updates

The new CapLoader release also comes with several other new features and updates, such as:

  • Added urlscan.io service for domain and IP lookups (right-click a flow or host to bring up the lookup menu).
  • Flow ID coloring based on 5-tuple, and clearer colors in timeline Gantt chart.
  • Extended default flow-timeout from 10 minutes to 2 hours for TCP flows.
  • Changed flow-timout for non-TCP flows to 60 seconds.
  • Upgraded to .NET Framework 4.7.2.

Updating to the Latest Release

Users who have previously purchased a license for CapLoader can download a free update to version 1.8 from our customer portal. All others can download a free 30 day trial from the CapLoader product page (no registration required).

Credits

We’d like to thank Mikael Harmark, Mandy van Oosterhout and Ulf Holmström for reporting bugs that have been fixed in this release. We’d also like to thank PaC for the DNS failure rate feature request mentioned in this blog post.

Posted by Erik Hjelmvik on Tuesday, 28 May 2019 10:45:00 (UTC/GMT)

Tags: #CapLoader #NetFlow #regex #DNS #DGA #Stratosphere

More... Share  |  Facebook   Twitter   Reddit   Hacker News Short URL: https://netresec.com/?b=1950482


DNS whitelisting in NetworkMiner

Stack of Papers by Jenni C

One of the new features in NetworkMiner Professional 1.5 is the ability to check if domain names in DNS requests/responses are “normal” or malicious ones. This lookup is performed offline using a local copy of Alexa's top 1 million domain name list.

We got the idea for this feature via Jarno Niemelä's great presentation titled “Making Life Difficult for Malware”. Despite working for F-Secure Jarno presents several smart ideas for avoiding malware infections without having to install an AV-product.

One of Jarno's slides contains the following suggestions:

Block Traffic To Sites Your Users Don’t Go To

Block subdomain hosting TLDs
  • co.cc, co.tv, ce.ms, rr.nu, cu.cc, cz.cc, vv.cc, cw.cm, cx.cc, etc
Block domains that provide dynamic DNS
  • *dyndns*, *no-ip*, 8866.org, thescx.info, 3322.org, sock8.com
Block file sharing sites, some malware use them
  • fileleave.com, dropbox.com, rapidshare.com, megafiles.com
For strict policy, allow DNS resolving only to Alexa top 1M[1]
  • Tip: Instead of null routing domains set up landing page
  • Either with a link that allows domain or IT ticket

Preventing users from visiting sites outside of the top 1 million websites (according to Alexa) sounds a bit harsh. In fact, we at Netresec just recently made it into the top 1M list (the current rank for netresec.com is 726 922). There are also many good and legit sites that are not yet on this list. Our idea is, however, to give analysts a heads up on queried DNS names that are not on the top 1M list by displaying this information in NetworkMiner's DNS tab.

NetworkMiner Professional 1.5 with DNS tab showing Alexa result for office.windowupdate.com

The screenshot above contains a lookup for the domain “office.windowupdate.com” (note the missing “s” in “windows”). This domain name was previously used by the C2 protocol Lurk (see Command Five's report “Command and Control in the Fifth Domain” for more details). The “Alexa Top 1M” column in NetworkMiner's DNS tab indicates whether or not the domain name is a well known domain. The malicious “office.windowupdate.com” is marked with “No”, while the proper “www.update.microsoft.com” is indeed on the list. It is, however, important to note that only the second-level domain is checked by NetworkMiner; i.e. in this case “windowupdate.com” and “microsoft.com”.

The DNS whitelisting technique can also come in handy when dealing with malware that employs domain generation algorithms (DGAs) (see the Damballa blog for additional info regarding DGAs). It is probably safe to say that these auto-generated domains should never show up in the Alexa Top 1M list.

Posted by Erik Hjelmvik on Wednesday, 02 October 2013 22:30:00 (UTC/GMT)

Tags: #Netresec #DNS #domain #DGA #malware #Alexa

More... Share  |  Facebook   Twitter   Reddit   Hacker News Short URL: https://netresec.com/?b=13A66EB

twitter

NETRESEC on Twitter

Follow @netresec on twitter:
» twitter.com/netresec


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)