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fix(rules): use exit event in reverse shell detection rule

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In some cases the rule is not triggered when a reverse shell is spawned.
That's because in the rule we are checking that the file descriptor passed
as argument to the dup functions is of type socket and its fd number is "0, 1, or 2"
and the event direction is "enter".
The following event does not trigger the rule: dup2(socket_fd, STDIN_FILENO);
But using the exit event the rule is triggered.

Signed-off-by: Aldo Lacuku <aldo@lacuku.eu>
This commit is contained in:
Aldo Lacuku 2022-06-20 10:33:44 +02:00 committed by poiana
parent 8a1f43f284
commit 07b4d5a47a
1 changed files with 1 additions and 1 deletions
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2
rules/falco_rules.yaml
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@ -2985,7 +2985,7 @@
- rule: Redirect STDOUT/STDIN to Network Connection in Container
desc: Detect redirecting stdout/stdin to network connection in container (potential reverse shell).
condition: evt.type=dup and evt.dir=> and container and fd.num in (0, 1, 2) and fd.type in ("ipv4", "ipv6") and not user_known_stand_streams_redirect_activities
condition: evt.type in (dup, dup2, dup3) and container and evt.rawres in (0, 1, 2) and fd.type in ("ipv4", "ipv6") and not user_known_stand_streams_redirect_activities
output: >
Redirect stdout/stdin to network connection (user=%user.name user_loginuid=%user.loginuid %container.info process=%proc.name parent=%proc.pname cmdline=%proc.cmdline terminal=%proc.tty container_id=%container.id image=%container.image.repository fd.name=%fd.name fd.num=%fd.num fd.type=%fd.type fd.sip=%fd.sip)
priority: WARNING