wlk.sh 3.79 KB
Newer Older
UltimateByte's avatar
UltimateByte committed
1
2
3
4
5
6
7
8
#!/bin/bash
# Name: Wrong Listener Killer
# Description: Makes sure that the wrong apps don't listen to the ports you want
# Help: Default settings are to make sure that what listens to port :80 is httpd and started as root
# Developer: Robin Labadie
# Version: 2017-05-24

## Settings
UltimateByte's avatar
UltimateByte committed
9
portcheck=":80" # Which port to check
UltimateByte's avatar
UltimateByte committed
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
allowedname="httpd" # Which process should we get on speccified port
allowedpath="/usr/sbin/httpd" # Which is the correct path to run it
allowedusers="root;" # Which is the correct user to run it (separate with ; )

logdir="/root" # Log directory (don't end with /)
maillog="root@localhost" # Mail to send an alert to if a threat is detected

## Misc vars
selfname="wlk" # Name of the script and log
log="${logdir}/${selfname}.log" # Define log name
maillogsize="10" # Define the amount of log to send by mail

## Logging
# Create logfile
if [ -n "${log}" ]&&[ ! -f "${log}" ]; then
	touch "${log}"
fi
# echo and log at the same time
fn_logecho(){
	currmessage="$@"
	echo -e "${currmessage}"
	echo -e "$(date +%Y-%m-%d_%H:%M:%S) - ${selfname} - ${currmessage}" >> "${log}"
}

fn_logecho "[START] Initiating ${selfname}"

## Find PIDs and define variables
# Seek PID of the app listening to port
pid="$(netstat -atunp | grep "${portcheck} " | grep LISTEN | awk '{print $7}' | awk -F "/" '{print $1}')"
# If no PID is found
if [ -z "${pid}" ]; then
	fn_logecho "[ERROR] Could not find a matching PID"
	fn_logecho " * It is likely that nothing listens to port ${portcheck}"
	exit 1
fi

# Check name of the process listening to port 80
pidname="$(netstat -atunp | grep "${portcheck} " | grep LISTEN | awk '{print $7}' | awk -F "/" '{print $2}')"
# Find out which user owns this PID
piduser="$(ps -u -p "${pid}" | tail -1 | awk '{print $1}')"
# Find out the start command (location) of the PID
pidcommand="$(ps -u -p "${pid}" | tail -1 | awk '{print $11}')"

# If one of these vars are unset, then something went wrong
if [ -z "${pidname}" ]||[ -z "${piduser}" ]||[ -z "${pidcommand}" ]; then
	fn_logecho "[ERROR] Could not find a matching PID"
	fn_logecho " * It is likely that nothing listens to port ${portcheck}"
	fn_logecho "Exiting"
	exit 1
fi

# Display some nice output to the user
fn_logecho "Current program listening to ${portcheck} is : PID: ${pid}\tName: ${pidname}\tUser: ${piduser}\tPath: ${pidcommand}"

## Evaluate issues
# Check if a malicious program is started
# 1) If the process name listening to port is wrong
if [ "${pidname}" != "${allowedname}" ]; then
	harm="1"	
	fn_logecho "[WARNING] Program listening to ${portcheck} is ${pidname} instead of ${allowedname}"
fi

# 2) If the process doesn't belong to an allowed user
usersamount="$(echo "${allowedusers}" | awk -F ';' '{ print NF }')"

# Recursively check if user is part of allowed users
allowedtorun="0"
for ((usersindex=1; usersindex <= usersamount; usersindex++)); do
	# Put current user into a test variable
	usertest="$(echo "${allowedusers}" | awk -F ';' -v x=${usersindex} '{ print $x }')"
	# Test if user is allowed, register success if so
	if [ "${piduser}" == "${usertest}" ]; then
		allowedtorun="1"
	fi
done
# User not allowed
if [ "${allowedtorun}" == "0" ]; then
	harm="1"
	fn_logecho "[WARNING] ${piduser} is not allowed to run ${allowedname}"
fi

# 3) If the process path isn't right
if [ "${pidcommand}" != "${allowedpath}" ]; then
	harm="1"
	fn_logecho "[WARNING] ${pidcommand} is not a valid path for ${allowedname}"
fi

## Take action
if [ "${harm}" == "1" ]; then
	fn_logecho "[ALERT] malicious process listening on port ${portcheck} found"
	fn_logecho "[INFO] The following process will be killed: ${pid} ${pidname} ${piduser} ${pidcommand}"
	kill -9 "${pid}"
	fn_logecho "[OK] Job done, exiting"
UltimateByte's avatar
UltimateByte committed
103
	tail -${maillogsize} "${log}" | mail -s "$(hostname -s) - ${pidname} - ${portcheck} killed" ${maillog}
UltimateByte's avatar
UltimateByte committed
104
105
106
else 
	fn_logecho "[OK] This program seems legit, exiting."
fi