Add additional rules/tests for pipe installers.

Add additional rules related to using pipe installers within a fbash
session:

 - Modify write_etc to only trigger if *not* in a fbash session. There's
   a new rule write_etc_installer which has the same conditions when in
   a fbash session, logging at INFO severity.

 - A new rule write_rpm_database warns if any non package management
   program tries to write below /var/lib/rpm.

 - Add a new warning if any program below a fbash session tries to open
   an outbound network connection on ports other than http(s) and dns.

 - Add INFO level messages when programs in a fbash session try to run
   package management binaries (rpm,yum,etc) or service
   management (systemctl,chkconfig,etc) binaries.

In order to test these new INFO level rules, make up a third class of
trace files traces-info.zip containing trace files that should result in
info-level messages.

To differentiate warning and info level detection, add an attribute to
the multiplex file "detect_level", which is "Warning" for the files in
traces-positive and "Info" for the files in traces-info. Modify
falco_test.py to look specifically for a non-zero count for the given
detect_level.

Doing this exposed a bug in the way the level-specific counts were being
recorded--they were keeping counts by level name, not number. Fix that.

.gitignore

@@ -4,6 +4,8 @@ test/falco_test.pyc
 test/falco_tests.yaml
 test/traces-negative
 test/traces-positive
+test/traces-info
+test/job-results
 
 userspace/falco/lua/re.lua
 userspace/falco/lua/lpeg.so

rules/falco_rules.yaml

@@ -124,7 +124,7 @@
 # The truncated dpkg-preconfigu is intentional, process names are
 # truncated at the sysdig level.
 - macro: package_mgmt_binaries
-  condition: proc.name in (dpkg, dpkg-preconfigu, rpm, yum)
+  condition: proc.name in (dpkg, dpkg-preconfigu, rpm, rpmkey, yum)
 
 # A canonical set of processes that run other programs with different
 # privileges or as a different user.
@@ -141,7 +141,7 @@
   condition: proc.name in (sendmail, sendmail-msp, postfix, procmail)
 
 - macro: sensitive_files
-  condition: (fd.name contains /etc/shadow or fd.name = /etc/sudoers or fd.directory = /etc/sudoers.d or fd.directory = /etc/pam.d or fd.name = /etc/pam.conf)
+  condition: (fd.name contains /etc/shadow or fd.name = /etc/sudoers or fd.directory in (/etc/sudoers.d, /etc/pam.d) or fd.name = /etc/pam.conf)
 
 # Indicates that the process is new. Currently detected using time
 # since process was started, using a threshold of 5 seconds.
@@ -194,11 +194,18 @@
   priority: WARNING
 
 - rule: write_etc
-  desc: an attempt to write to any file below /etc
-  condition: evt.dir = < and open_write and not shadowutils_binaries and not sysdigcloud_binaries_parent and not package_mgmt_binaries and etc_dir
+  desc: an attempt to write to any file below /etc, not in a pipe installer session
+  condition: evt.dir = < and open_write and not shadowutils_binaries and not sysdigcloud_binaries_parent and not package_mgmt_binaries and etc_dir and not proc.sname=fbash
   output: "File below /etc opened for writing (user=%user.name command=%proc.cmdline file=%fd.name)"
   priority: WARNING
 
+# Within a fbash session, the severity is lowered to INFO
+- rule: write_etc_installer
+  desc: an attempt to write to any file below /etc, in a pipe installer session
+  condition: evt.dir = < and open_write and not shadowutils_binaries and not sysdigcloud_binaries_parent and not package_mgmt_binaries and etc_dir and proc.sname=fbash
+  output: "File below /etc opened for writing (user=%user.name command=%proc.cmdline file=%fd.name) within pipe installer session"
+  priority: INFO
+
 - rule: read_sensitive_file_untrusted
   desc: an attempt to read any sensitive file (e.g. files containing user/password/authentication information). Exceptions are made for known trusted programs.
   condition: open_read and not user_mgmt_binaries and not userexec_binaries and not proc.name in (iptables, ps, lsb_release, check-new-relea, dumpe2fs, accounts-daemon, bash, sshd) and not cron and sensitive_files
@@ -211,6 +218,13 @@
   output: "Sensitive file opened for reading by trusted program after startup (user=%user.name command=%proc.cmdline file=%fd.name)"
   priority: WARNING
 
+# Only let rpm-related programs write to the rpm database
+- rule: write_rpm_database
+  desc: an attempt to write to the rpm database by any non-rpm related program
+  condition: open_write and not proc.name in (rpm,rpmkey,yum) and fd.directory=/var/lib/rpm
+  output: "Rpm database opened for writing by a non-rpm program (command=%proc.cmdline file=%fd.name)"
+  priority: WARNING
+
 - rule: db_program_spawned_process
   desc: a database-server related program spawned a new process other than itself. This shouldn\'t occur and is a follow on from some SQL injection attacks.
   condition: db_server_binaries_parent and not db_server_binaries and spawned_process
@@ -312,17 +326,45 @@
 
 # fbash is a small shell script that runs bash, and is suitable for use in curl <curl> | fbash installers.
 - rule: installer_bash_starts_network_server
-  desc: an attempt by any program that is in a session led by fbash to start listening for network connections
+  desc: an attempt by a program in a pipe installer session to start listening for network connections
   condition: evt.type=listen and proc.sname=fbash
   output: "Unexpected listen call by a process in a fbash session (command=%proc.cmdline)"
   priority: WARNING
 
 - rule: installer_bash_starts_session
-  desc: an attempt by any program that is in a session led by fbash to start a new session
+  desc: an attempt by a program in a pipe installer session to start a new session
   condition: evt.type=setsid and proc.sname=fbash
   output: "Unexpected setsid call by a process in fbash session (command=%proc.cmdline)"
   priority: WARNING
 
+- rule: installer_bash_non_https_connection
+  desc: an attempt by a program in a pipe installer session to make an outgoing connection on a non-http(s) port
+  condition: outbound and not fd.sport in (80, 443, 53) and proc.sname=fbash
+  output: "Outbound connection on non-http(s) port by a process in a fbash session (command=%proc.cmdline connection=%fd.name)"
+  priority: WARNING
+
+# It'd be nice if we could warn when processes in a fbash session try
+# to download from any nonstandard location? This is probably blocked
+# on https://github.com/draios/falco/issues/88 though.
+
+# Notice when processes try to run chkconfig/systemctl.... to install a service.
+# Note: this is not a WARNING, as you'd expect some service management
+# as a part of doing the installation.
+- rule: installer_bash_manages_service
+  desc: an attempt by a program in a pipe installer session to manage a system service (systemd/chkconfig)
+  condition: evt.type=execve and proc.name in (chkconfig, systemctl) and proc.sname=fbash
+  output: "Service management program run by process in a fbash session (command=%proc.cmdline)"
+  priority: INFO
+
+# Notice when processes try to run any package management binary within a fbash session.
+# Note: this is not a WARNING, as you'd expect some package management
+# as a part of doing the installation
+- rule: installer_bash_runs_pkgmgmt
+  desc: an attempt by a program in a pipe installer session to run a package management binary
+  condition: evt.type=execve and package_mgmt_binaries and proc.sname=fbash
+  output: "Package management program run by process in a fbash session (command=%proc.cmdline)"
+  priority: INFO
+
 ###########################
 # Application-Related Rules
 ###########################

test/falco_test.py

@@ -18,6 +18,9 @@ class FalcoTest(Test):
         self.should_detect = self.params.get('detect', '*')
         self.trace_file = self.params.get('trace_file', '*')
 
+        if self.should_detect:
+            self.detect_level = self.params.get('detect_level', '*')
+
         # Doing this in 2 steps instead of simply using
         # module_is_loaded to avoid logging lsmod output to the log.
         lsmod_output = process.system_output("lsmod", verbose=False)
@@ -44,17 +47,29 @@ class FalcoTest(Test):
                 cmd, res.exit_status))
 
         # Get the number of events detected.
-        res = re.search('Events detected: (\d+)', res.stdout)
-        if res is None:
+        match = re.search('Events detected: (\d+)', res.stdout)
+        if match is None:
             self.fail("Could not find a line 'Events detected: <count>' in falco output")
 
-        events_detected = int(res.group(1))
+        events_detected = int(match.group(1))
 
         if not self.should_detect and events_detected > 0:
             self.fail("Detected {} events when should have detected none".format(events_detected))
 
-        if self.should_detect and events_detected == 0:
-            self.fail("Detected {} events when should have detected > 0".format(events_detected))
+        if self.should_detect:
+            if events_detected == 0:
+                self.fail("Detected {} events when should have detected > 0".format(events_detected))
+
+            level_line = '{}: (\d+)'.format(self.detect_level)
+            match = re.search(level_line, res.stdout)
+
+            if match is None:
+                self.fail("Could not find a line '{}: <count>' in falco output".format(self.detect_level))
+
+            events_detected = int(match.group(1))
+
+            if not events_detected > 0:
+                self.fail("Detected {} events at level {} when should have detected > 0".format(events_detected, self.detect_level))
 
         pass
 

test/run_regression_tests.sh

@@ -5,7 +5,8 @@ SCRIPTDIR=$(dirname $SCRIPT)
 MULT_FILE=$SCRIPTDIR/falco_tests.yaml
 
 function download_trace_files() {
-    for TRACE in traces-positive traces-negative ; do
+    for TRACE in traces-positive traces-negative traces-info ; do
+	rm -rf $SCRIPTDIR/$TRACE
 	curl -so $SCRIPTDIR/$TRACE.zip https://s3.amazonaws.com/download.draios.com/falco-tests/$TRACE.zip &&
 	unzip -d $SCRIPTDIR $SCRIPTDIR/$TRACE.zip &&
 	rm -rf $SCRIPTDIR/$TRACE.zip
@@ -21,6 +22,7 @@ function prepare_multiplex_file() {
 	cat << EOF >> $MULT_FILE
   $NAME:
     detect: True
+    detect_level: Warning
     trace_file: $trace
 EOF
     done
@@ -35,6 +37,17 @@ EOF
 EOF
     done
 
+    for trace in $SCRIPTDIR/traces-info/*.scap ; do
+	[ -e "$trace" ] || continue
+	NAME=`basename $trace .scap`
+	cat << EOF >> $MULT_FILE
+  $NAME:
+    detect: True
+    detect_level: Informational
+    trace_file: $trace
+EOF
+    done
+
     echo "Contents of $MULT_FILE:"
     cat $MULT_FILE
 }

userspace/falco/lua/rule_loader.lua

@@ -102,14 +102,13 @@ function set_output(output_format, state)
 end
 
 local function priority(s)
-   valid_levels = {"emergency", "alert", "critical", "error", "warning", "notice", "informational", "debug"}
    s = string.lower(s)
-   for i,v in ipairs(valid_levels) do
-      if (string.find(v, "^"..s)) then
+   for i,v in ipairs(output.levels) do
+      if (string.find(string.lower(v), "^"..s)) then
 	 return i - 1 -- (syslog levels start at 0, lua indices start at 1)
       end
    end
-   error("Invalid severity level: "..level)
+   error("Invalid severity level: "..s)
 end
 
 -- Note that the rules_by_name and rules_by_idx refer to the same rule
@@ -232,8 +231,8 @@ end
 
 local rule_output_counts = {total=0, by_level={}, by_name={}}
 
-for idx, level in ipairs(output.levels) do
-   rule_output_counts[level] = 0
+for idx=0,table.getn(output.levels)-1,1 do
+   rule_output_counts.by_level[idx] = 0
 end
 
 function on_event(evt_, rule_id)
@@ -265,8 +264,8 @@ function print_stats()
    print("Rule counts by severity:")
    for idx, level in ipairs(output.levels) do
       -- To keep the output concise, we only print 0 counts for error, warning, and info levels
-      if rule_output_counts[level] > 0 or level == "Error" or level == "Warning" or level == "Informational" then
-	 print ("   "..level..": "..rule_output_counts[level])
+      if rule_output_counts.by_level[idx-1] > 0 or level == "Error" or level == "Warning" or level == "Informational" then
+	 print ("   "..level..": "..rule_output_counts.by_level[idx-1])
       end
    end