EscInSecurity: Weekly TrickBot Analysis - End of w/c 04-Jun-2018 to A-1000209, B-1000068, and C-1000198

Here are the results of my analysis of TrickBot Banking Trojan mcconfs shared up to the end of the week commencing 4th June 2018. This analysis covers 2,366 unique C2 IP addresses used in 460 mcconfs across 262 versions, with highest versions of A-1000209, B-1000068, and C-1000198.

Background:
Since its first use from approximately 19th October 2016, TrickBot has frequently issued new versions of its XML configuration file, mcconf. Originally there was a single chain of config versions which started at 1000002. (There may have been a 1000001 but it is not been shared publicly.) I refer to this original sequence as iteration A. On 16th November 2017 TrickBot mcconfs were issued for older version numbers than the current iteration A configs, but with different command and control (C2) servers to those in that version's iteration A config. This indicated the start of iteration B, a new sequence of configs believed to be for a second botnet. While there is a small amount of overlap of the C2 servers between iteration A and iteration B, the majority of C2 servers are specific to an iteration (hence botnet). The iteration B botnet stopped receiving new configs on 28th February 2018. As of 28th March 2018 another iteration, iteration C, was started, once again repeating previously used version numbers but with different C2 server lists. Victim hosts in that third botnet were merged into the iteration A botnet as of 23rd May 2018.

This week's analysis:
Figure 1 shows the rate of discovery of TrickBot versions in the wild, based on shared mcconfs. The flatter the line, the more frequently versions are discovered. Ignore the two long, almost vertical lines which coincide with the switch from one iteration to the next. These vertical lines are purely an artefact of graphing the data in a single series. (Note: Full size versions of all the graphs and tables are available via the link at the end of this post.)

There were four new config versions discovered in the week commencing 4th June 2018 (A-1000206, A-1000207, A-1000208, and A-1000209), five the week before, and six the week before that. All new config versions extend the iteration A botnet, taking this to 1000209. The secondary, iteration B, botnet was not extended in the discovered versions and remains unchanged since 1000068 of 28th February 2018. The tertiary, iteration C, botnet was merged into the iteration A botnet on 23rd May 2018.

Figure 1 - TrickBot Version Discovery Dates

The following graphs (Figures 2 and 3) show the number of server entries using ports:

443 (HTTPS);
444 (Simple Network Paging Protocol) -- INACTIVE;
445 (IBM AS Server Mapper) -- INACTIVE;
449 (Cray Network Semaphore Server); and
451 (SMB) -- INACTIVE.

Figure 2 is for iteration A configs, Figure 3 is for previous iteration B and C configs. Since mid April, the length of the C2 server lists has stabilised significantly in iteration A configs, with between 25 and 33 server entries. The percentage of :443 (HTTPS) servers in those lists has steadily increased, from 1/3rd to 2/3rd of the list, since late April.

Figure 2 - TrickBot SRV Port Usage (Iteration A)

Figure 3 - TrickBot SRV Port Usage (Iterations B and C)

Figure 4 shows the top 25 servers (of 2,366 unique) used within the 262 versions. There were a large number of changes in the top 25, with numerous servers used this week moving up the ranking (as can be seen by the last used version number). Notably, the top server, 185[.]42[.]192[.]194[:]449, pulled further into the lead and has been used in 35.7% more configs than any other server.

Figure 4 - TrickBot Top 25 SRV

Figure 5 shows the breakdown of detected TrickBot campaign 'gtag' (group tags) values used in the 460 mcconfs analysed. (Yes, I know it's unreadable - it's just here as a placeholder. A full size version is available in the downloadable zip file at the bottom of the post.)

Figure 5 - TrickBot gtag Breakdown

52 C2 servers were used in the mcconfs from this week, of which 27 (52%) were new. Figure 6 shows the proportional server count of mcconfs shared each week (when compared to the greatest count in a week), along with the percentage churn of the servers. The trend line highlights that the churn percentage is reducing, with an increasing number of servers being re-used from one week to the next.

Figure 6 - TrickBot Weekly Advertised SRV Count and Churn

The BGP prefix registrations for the C2 server IP addresses continue to be heavily biased to ASN routed through RU (and so Figure 7's Y-axis is cut short to allow clearer viewing of other country counts). The new servers' IP addresses are associated with ASN routed to: 13xRU, 3xPL, 3xUA, 2xID, 2xNL, 1xCL 1xCZ, 1xGH, and 1xUS.

Figure 7 - TrickBot SRV IP Address BGP Prefix Country Codes

Figure 8 shows the geographical location of 49 (those with location data) of 49 (scanned by Shodan) of the 52 C2 server IP addresses used in the analysed configs.

According to Shodan's most recent data:

16 are Ubiquiti devices and 10 are MikroTik devices.
20 are running Dropbear SSH, 17 are running OpenSSH, 14 are running nginx, four are running Apache, two are running Exim, two are running MySQL, 1 is running Microsoft FTP, 1 is running Postfix.

Figure 8 - TrickBot C2 Server IP Locations For New Configs

Figure 9 shows the BGP allocations of C2 servers' IP addresses to country by TrickBot version. (Once again, I know it's unreadable - it's just here as a placeholder. A full size version is available in the downloadable zip file at the bottom of the post.)