The first red flag you mentioned - abnormal network traffic from random high ports - is indeed concerning. Let's start by mapping these connections to processes:

# Comprehensive network process mapping
sudo netstat -tulnp
sudo ss -tulnp
# For more detailed socket information
sudo lsof -i -P -n

Standard process viewers can be bypassed by rootkits. Here's how to perform deeper analysis:

# Compare different process listing methods
ps auxf
top -H -b -n 1
htop
# Check for discrepancies between /proc and process lists
ls -la /proc/[0-9]*/exe | awk '{print $11}' | sort | uniq

Rootkits often hide their files using various techniques. Try these detection methods:

# Find unlinked (hidden) but still running processes
sudo grep -l ' (deleted)' /proc/*/exe
# Check for suspicious hidden directories
sudo find / -type d -name ".*" -print
# Verify critical binaries
for bin in $(which ls ps netstat sshd); do rpm -Vf $bin || echo "$bin modified"; done

Malicious kernel modules (LKM rootkits) require special attention:

# List loaded modules
lsmod
# Compare with expected modules
cat /proc/modules
# Check module signatures (if enabled)
sudo modinfo $(lsmod | awk '{print $1}' | tail -n +2)

Volatile memory analysis can reveal hidden processes:

# Install and use LiME for memory acquisition
sudo apt-get install lime-forensics
sudo insmod ./lime-forensics.ko "path=/tmp/memdump.lime format=lime"
# Then analyze with Volatility Framework
vol.py -f /tmp/memdump.lime linux_pslist

For future protection, implement these monitoring solutions:

# Auditd configuration for process monitoring
sudo apt-get install auditd
sudo auditctl -a exit,always -F arch=b64 -S execve
sudo auditctl -a exit,always -F arch=b32 -S execve
# Monitor critical directories
sudo auditctl -w /bin/ -p wa -k system_binaries
sudo auditctl -w /sbin/ -p wa -k system_sbinaries

Set up automated integrity verification with tools like AIDE:

# Initial setup
sudo apt-get install aide
sudo aideinit
# Daily check via cron
0 0 * * * /usr/bin/aide --check | mail -s "AIDE Report" admin@example.com

If you confirm a compromise, follow these steps:

# Capture forensic evidence first
sudo dd if=/dev/sda of=/mnt/evidence/sda.img bs=4M
# Then isolate the system
sudo iptables -A INPUT -j DROP
sudo iptables -A OUTPUT -j DROP

When noticing abnormal network patterns like random high-port connections, your first instinct should be to suspect process hiding techniques. Common indicators include:

• Unexpected TCP/UDP connections on ephemeral ports (32768-60999)
• CPU/memory usage discrepancies between system monitors and process lists
• Modified timestamps on critical system binaries (ls, ps, netstat)

Begin with these diagnostic commands to identify inconsistencies:

# Compare process lists from different sources
ps aux
ls -la /proc/*/exe 2>/dev/null | grep deleted

# Network connection verification
netstat -tulnp
ss -tulnp
lsof -i -P -n

# Loaded kernel module check
lsmod
cat /proc/modules

For sophisticated rootkits that hook system calls, use these methods:

# Check for LD_PRELOAD hijacking
cat /proc/*/environ | grep LD_PRELOAD

# Verify system call tables
grep sys_call_table /boot/System.map-$(uname -r)

# Use statically compiled tools
busybox ps
busybox netstat

Implement these ongoing monitoring strategies:

# Cron job for process auditing
*/5 * * * * root /usr/bin/diff <(ps -eo pid,cmd) <(/bin/ps -eo pid,cmd)

# Kernel module monitoring
#!/bin/bash
while true; do
    diff <(lsmod | sort) <(cat /tmp/lsmod.baseline | sort)
    sleep 300
done

If compromise is confirmed:

1. Isolate the machine immediately
2. Capture volatile memory (using LiME or fmem)
3. Create disk images for forensic analysis
4. Rotate all credentials that may have been exposed