Elastic Defend high stable eql
Egress Network Connection from Memory File Descriptor
This rule detects when a process creates an in-memory file descriptor (memfd_create) followed by an egress network connection from an unusual executable. This activity indicates an active attempt to execute a fileless payload and should be considered highly abnormal or suspicious. This activity can occur when the memfd syscall is used to create a memory-resident file, such as a payload, and then execute it, after which it establishes outbound network connections for command-and-control (C2).
Detection Logic
sequence by process.entity_id with maxspan=10s
[process where event.type == "start" and event.action == "memfd_create" and (
process.executable like (
"memfd:*", "?memfd:*", "/tmp/*", "/var/tmp/*", "/dev/shm/*", "./*", "/run/user/*", "/var/run/user/*",
"/boot/*", "/sys/*", "/lost+found/*", "/proc/*", "/var/mail/*", "/var/www/*", "/home/*/*", "/root/*"
) or
(process.name like "python*" and process.args == "-c") or
(process.name like ("perl*", "ruby*", "lua*", "node", "nodejs") and process.args like "-e*") or
(process.name like "php*" and process.args like "-r*") or
process.name like (".*", "*.py", "*.pyc", "*.lua", "*.pl", "*.rb", "*.bin", "*.php", "*.js", "*.mjs") or
(
process.name like ("python*", "perl*", "php*", "ruby*", "lua*", "node", "java", "javaw") and
(
process.args like (
"/tmp/*", "/var/tmp/*", "/dev/shm/*", "./*", "/run/user/*", "/var/run/user/*",
"/boot/*", "/sys/*", "/lost+found/*", "/proc/*", "/var/mail/*", "/var/www/*",
"/home/*/*", "/root/*"
) and process.args_count <= 2
)
)
) and
process.parent.name in ("bash", "dash", "sh", "tcsh", "csh", "zsh", "ksh", "fish", "mksh", "busybox") and
not (
process.executable like (
"/tmp/.mount_*", "/nix/store/*/bin/.qemu-system-x86_64-wrapped", "/root/.local/share/claude/versions/*", "/home/*/*/*",
"/usr/bin/qgis.bin", "/app/bin/evolution.bin", "/opt/cpanel/ea-php*/root/usr/bin/php-cgi", "/nix/store/*/bin/.obs-wrapped"
) or
process.command_line == "/usr/bin/php /var/www/glpi/front/cron.php" or
(
process.executable == "/home/runner/bin/Runner.Listener" and
process.Ext.memfd.name == "memfd:doublemapper"
) or
(
process.name like "php*" and
process.Ext.memfd.name in ("opcache_lock", "anon_hugepage")
) or
(
process.executable == "/app/bin/evolution.bin" and
process.Ext.memfd.name == "memfd:WebKitSharedMemory"
) or
(
process.name like "python*" and
process.Ext.memfd.name == "wayland-shm"
) or
(
process.executable like "/home/*/.local/share/claude/versions/*" and
process.Ext.memfd.name in ("memfd:spawn_stdio_stdin", "spawn_stdio_stdin")
) or
(
process.executable like "/home/*/.elixir-install/installs/otp/*/bin/beam.smp" and
process.Ext.memfd.name == "memfd:vmem"
) or
(
process.name == "dotnet" and
process.Ext.memfd.name == "memfd:doublemapper"
) or
(
process.executable == "/usr/bin/php" and
process.args like "/var/www/html/*"
) or
(
process.executable like "/usr/bin/php*" and
process.working_directory like "/var/www/vhosts/*"
) or
(
process.executable like "*/.opencode/bin/opencode*" and
process.Ext.memfd.name == "memfd:spawn_stdio_stdin"
)
)]
[network where event.type == "start" and event.action == "connection_attempted" 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"
)
)]Field Validations
Loading…
Comments (0)
Loading comments...