Crypto Mining Is More Popular Than Ever!
We already wrote some diaries about crypto miners and they remain more popular than ever. Based on my daily hunting statistics, we can see that malicious scripts performing crypto mining operations remain on top of the sample I detected for the last 24h:
(They are represented by the ‘PowershellSuspiciousStrings’ category)
But crypto miners are not only installed on workstations, servers are juicy targets too... because that’s where the real CPU power is available! The recent Apache Struts remote code execution vulnerability (amongst other like SOLR reported by Renato a few months ago[1]) is heavily used to drop crypto miners on vulnerable systems[2].
The classic behaviour of a crypto miner dropper is to try to gain as much as available resources. To do so, they usually try to kill competitors (See my previous diary[3]).
Yesterday I came across another shell script which drops a Monero crypto miner unknown on VT (SHA256:b565d406dbb6a3aa80bc1e514b176e9ee6415eb0f425d013154e0cde555374e7). The script has nothing fancy, it downloads a Monero crypto miner and adds persistency via a cron job. However, this one improved the detection of other CPU intensive processes!
Here are some examples extracted from the sample:
It kills processes containing the following IP addresses on the command line:
It removes the memory segment used by JBoss:
rm -rf /dev/shm/jboss
Here is the list of substrings searched to kill processes using the 'pkill' command:
$ grep ^pkill b565d406dbb6a3aa80bc1e514b176e9ee6415eb0f425d013154e0cde555374e7.vir | awk '{ print $NF }'|sort -u ./AnXqV.yam ./BI5zj ./Carbon ./Duck.sh ./Guard.sh ./JnKihGjn ./KGlJwfWDbCPnvwEJupeivI1FXsSptuyh ./NXLAi ./XJnRj ./accounts-daemon ./acpid ./askdljlqw ./atd ./bonn.sh ./bonns ./carbon ./conn.sh ./conns ./crypto-pool ./ddg ./donns ./gekoCrw ./gekoCrw32 ./gekoba2anc1 ./gekoba5xnc1 ./gekobalanc1 ./gekobalance ./gekobalanq1 ./gekobnc1 ./ir29xc1 ./irpbalanc1 ./jIuc2ggfCAvYmluL2Jhc2gi ./jaav ./jva ./kw.sh ./kworker34 ./kxjd ./lexarbalanc1 ./lower.sh ./lowerv2.sh ./lowerv3.sh ./minerd ./minergate ./minergate-cli ./minexmr ./mixnerdx ./mule ./mutex ./myatd ./performedl ./polkitd ./pro.sh ./pubg ./pvv ./root.sh ./rootv2.sh ./rootv3.sh ./servcesa ./sleep ./sourplum ./sshd ./stratum ./vsp ./watch-smart ./wget ./ysaydh /tmp/httpd.conf /tmp/m /tmp/wa/httpd.conf AnXqV.yam BI5zj Carbon Duck.sh Guard.sh JnKihGjn KGlJwfWDbCPnvwEJupeivI1FXsSptuyh NXLAi XJnRj accounts-daemon acpid askdljlqw atd bb bonn.sh bonns carbon conn.sh conns crypto-pool ddg donns gekoCrw gekoCrw32 gekoba2anc1 gekoba5xnc1 gekobalanc1 gekobalance gekobalanq1 gekobnc1 ir29xc1 irpbalanc1 irqba2anc1 irqba5xnc1 irqbalance irqbnc1 jIuc2ggfCAvYmluL2Jhc2gi jaav jva kw.sh kworker34 kxjd lexarbalanc1 lower.sh lowerv2.sh lowerv3.sh minerd minergate minergate-cli minexmr mixnerdx mule mutex myatd performedl polkitd pro.sh pubg pvv root.sh rootv2.sh rootv3.sh servcesa sleep sourplum stratum tratum vsp watch-smart wget yam ysaydh
You can see that the list keeps growing! Note that the script also tries to optimize the system performance by altering the memory paging mechanism[4]:
proc=`grep -c ^processor /proc/cpuinfo` cores=$(($proc+1)) num=$(($cores*3)) /sbin/sysctl -w vm.nr_hugepages=`$num`
Yes, the battle for more CPU cycles is still ongoing!
[1] https://isc.sans.edu/forums/diary/Apache+SOLR+the+new+target+for+cryptominers/23425
[2] https://www.volexity.com/blog/2018/08/27/active-exploitation-of-new-apache-struts-vulnerability-cve-2018-11776-deploys-cryptocurrency-miner/
[3] https://isc.sans.edu/forums/diary/The+Crypto+Miners+Fight+For+CPU+Cycles/23407
[4] https://wiki.debian.org/Hugepages
Xavier Mertens (@xme)
Senior ISC Handler - Freelance Cyber Security Consultant
PGP Key
Reverse-Engineering Malware: Advanced Code Analysis | Singapore | Nov 18th - Nov 22nd 2024 |
Comments
Anonymous
Aug 30th 2018
6 years ago
Crypto miners in the browser being mainly pieces of JavaScript, you could have a look at JavaScript blockers.
Anonymous
Aug 30th 2018
6 years ago