osquery-defense-kit/detection/execution/unexpected-chmod-exec-event-linux.sql
2023-03-17 15:19:33 -04:00

116 lines
3.7 KiB
SQL

-- Things that call chmod to set executable permissions
--
-- references:
-- * https://www.microsoft.com/en-us/security/blog/2022/05/19/rise-in-xorddos-a-deeper-look-at-the-stealthy-ddos-malware-targeting-linux-devices/
--
-- false positives:
-- * loads of them
--
-- tags: transient process events
-- platform: linux
-- interval: 180
SELECT
IFNULL(
REGEX_MATCH (TRIM(pe.cmdline), '.* (/.*)', 1),
CONCAT (
pe.cwd,
'/',
REGEX_MATCH (TRIM(pe.cmdline), '.* (.*)', 1)
)
) AS f_path,
f.mode AS f_mode,
f.type AS f_type,
hash.sha256 AS f_hash,
magic.data AS f_magic,
-- Child
pe.path AS p0_path,
TRIM(pe.cmdline) AS p0_cmd,
pe.cwd AS p0_cwd,
pe.pid AS p0_pid,
-- Parent
pe.parent AS p1_pid,
p1.cgroup_path AS p1_cgroup,
TRIM(COALESCE(p1.cmdline, pe1.cmdline)) AS p1_cmd,
COALESCE(p1.path, pe1.path) AS p1_path,
COALESCE(p_hash1.sha256, pe_hash1.sha256) AS p1_hash,
REGEX_MATCH (COALESCE(p1.path, pe1.path), '.*/(.*)', 1) AS p1_name,
-- Grandparent
COALESCE(p1.parent, pe1.parent) AS p2_pid,
COALESCE(p1_p2.cgroup_path, pe1_p2.cgroup_path) AS p2_cgroup,
TRIM(
COALESCE(p1_p2.cmdline, pe1_p2.cmdline, pe1_pe2.cmdline)
) AS p2_cmd,
COALESCE(p1_p2.path, pe1_p2.path, pe1_pe2.path) AS p2_path,
COALESCE(
p1_p2_hash.path,
pe1_p2_hash.path,
pe1_pe2_hash.path
) AS p2_hash,
REGEX_MATCH (
COALESCE(p1_p2.path, pe1_p2.path, pe1_pe2.path),
'.*/(.*)',
1
) AS p2_name,
-- Exception key
REGEX_MATCH (pe.path, '.*/(.*)', 1) || ',' || MIN(pe.euid, 500) || ',' || REGEX_MATCH (COALESCE(p1.path, pe1.path), '.*/(.*)', 1) || ',' || REGEX_MATCH (
COALESCE(p1_p2.path, pe1_p2.path, pe1_pe2.path),
'.*/(.*)',
1
) AS exception_key
FROM
process_events pe
LEFT JOIN processes p ON pe.pid = p.pid
-- Wow, you can do that?
LEFT JOIN file f ON IFNULL(
REGEX_MATCH (TRIM(pe.cmdline), '.* (/.*)', 1),
CONCAT (
pe.cwd,
'/',
REGEX_MATCH (TRIM(pe.cmdline), '.* (.*)', 1)
)
) = f.path
LEFT JOIN hash ON f.path = hash.path
LEFT JOIN magic ON f.path = magic.path
-- Parents (via two paths)
LEFT JOIN processes p1 ON pe.parent = p1.pid
LEFT JOIN hash p_hash1 ON p1.path = p_hash1.path
LEFT JOIN process_events pe1 ON pe.parent = pe1.pid
AND pe1.cmdline != ''
LEFT JOIN hash pe_hash1 ON pe1.path = pe_hash1.path
-- Grandparents (via 3 paths)
LEFT JOIN processes p1_p2 ON p1.parent = p1_p2.pid -- Current grandparent via parent processes
LEFT JOIN processes pe1_p2 ON pe1.parent = pe1_p2.pid -- Current grandparent via parent events
LEFT JOIN process_events pe1_pe2 ON pe1.parent = pe1_p2.pid
AND pe1_pe2.cmdline != '' -- Past grandparent via parent events
LEFT JOIN hash p1_p2_hash ON p1_p2.path = p1_p2_hash.path
LEFT JOIN hash pe1_p2_hash ON pe1_p2.path = pe1_p2_hash.path
LEFT JOIN hash pe1_pe2_hash ON pe1_pe2.path = pe1_pe2_hash.path
WHERE
pe.pid IN (
SELECT DISTINCT
pid
FROM
process_events
WHERE
time > (strftime('%s', 'now') -180)
AND pe.syscall = "execve"
AND (
cmdline LIKE '%chmod% 7%'
OR cmdline LIKE '%chmod% +rwx%'
OR cmdline LIKE '%chmod% +x%'
OR cmdline LIKE '%chmod% u+x%'
OR cmdline LIKE '%chmod% a+x%'
)
AND cmdline NOT LIKE 'chmod 777 /app/%'
AND cmdline NOT LIKE 'chmod 700 /tmp/apt-key-gpghome.%'
AND cmdline NOT LIKE 'chmod 700 /home/%/snap/%/%/.config'
)
AND pe.syscall = "execve"
AND f.type != 'directory'
AND p1_cgroup NOT LIKE '/system.slice/docker-%'
AND p1_cgroup NOT LIKE '/user.slice/user-1000.slice/user@1000.service/user.slice/nerdctl-%'
AND p2_cgroup NOT LIKE '/system.slice/docker-%'
AND p2_cgroup NOT LIKE '/user.slice/user-1000.slice/user@1000.service/user.slice/nerdctl-%'
GROUP BY
p0_pid