Egress Connection by a YUM Package Manager Descendant
Description
Detects suspicious network events executed by the Yum package manager, potentially indicating persistence through a Yum
backdoor. In Linux, Yum (Yellowdog Updater, Modified) is a command-line utility used for handling packages on
Fedora-based systems, providing functions for installing, updating, upgrading, and removing software along with managing
package repositories. Attackers can backdoor Yum to gain persistence by injecting malicious code into plugins that Yum
runs, thereby ensuring continued unauthorized access or control each time Yum is used for package management. For this
persistence mechanism to work, plugins need to be enabled in the /etc/dnf/dnf.conf and plugin.conf files.
Query · eql
sequence by process.entity_id with maxspan=5s
[process where event.type == "start" and event.action == "exec" and (
process.name : (
"bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish", "python*", "php*",
"perl", "ruby", "lua*", "openssl", "nc", "ncat", "netcat", "netcat.openbsd",
"netcat.traditional", "nc.openbsd", "nc.traditional", "telnet", "awk"
) or
process.executable : (
"./*", "/boot/*", "/dev/shm/*", "/etc/cron.*/*", "/etc/init.d/*", "/etc/update-motd.d/*", "/run/*", "/srv/*",
"/tmp/*", "/var/tmp/*", "/var/log/*"
)
) and descendant of [process where event.action == "exec" and process.name == "yum"] and not (
process.executable : "/run/user/*/newroot/*" or
process.args : "/usr/local/cpanel/*"
)
]
[network where event.action == "connection_attempted" and event.type == "start" and not (
destination.ip == null or destination.ip == "0.0.0.0" or cidrmatch(
destination.ip, "10.0.0.0/8", "127.0.0.0/8", "169.254.0.0/16", "172.16.0.0/12", "192.0.0.0/24", "192.0.0.0/29",
"192.0.0.8/32", "192.0.0.9/32", "192.0.0.10/32", "192.0.0.170/32", "192.0.0.171/32", "192.0.2.0/24",
"192.31.196.0/24", "192.52.193.0/24", "192.168.0.0/16", "192.88.99.0/24", "224.0.0.0/4", "100.64.0.0/10",
"192.175.48.0/24","198.18.0.0/15", "198.51.100.0/24", "203.0.113.0/24", "240.0.0.0/4", "::1", "FE80::/10",
"FF00::/8", "172.31.0.0/16"
) or
process.name in ("yumBackend.py", "urlgrabber-ext-down") or
process.executable in ("/usr/share/logstash/jdk/bin/java", "/opt/java/openjdk/bin/java", "/usr/local/cpanel/scripts/rebuildhttpdconf")
)
]