Answer : A
Step 1: Define the Problem and Objective
Objective:
We need to identify the following from the webserver-auth-logs.txt file:
The IP address performing a brute force attack.
The total number of successful authentications made by that IP.
Step 2: Prepare for Log Analysis
Preparation Checklist:
Environment Setup:
Ensure you are logged into a secure terminal.
Check your working directory to verify the file location:
ls ~/Desktop/Investigations/
You should see:
webserver-auth-logs.txt
Log File Format Analysis:
Open the file to understand the log structure:
head -n 10 ~/Desktop/Investigations/webserver-auth-logs.txt
Look for patterns such as:
pg
2025-04-07 12:34:56 login attempt from 192.168.1.1 - SUCCESS
2025-04-07 12:35:00 login attempt from 192.168.1.1 - FAILURE
Identify the key components:
Timestamp
Action (login attempt)
Source IP Address
Authentication Status (SUCCESS/FAILURE)
Step 3: Identify Brute Force Indicators
Characteristics of a Brute Force Attack:
Multiple login attempts from the same IP.
Combination of FAILURE and SUCCESS messages.
High volume of attempts compared to other IPs.
Step 3.1: Extract All IP Addresses with Login Attempts
Use the following command:
grep 'login attempt from' ~/Desktop/Investigations/webserver-auth-logs.txt | awk '{print $6}' | sort | uniq -c | sort -nr > brute-force-ips.txt
grep 'login attempt from': Finds all login attempt lines.
awk '{print $6}': Extracts IP addresses.
sort | uniq -c: Groups and counts IP occurrences.
sort -nr: Sorts counts in descending order.
> brute-force-ips.txt: Saves the output to a file for documentation.
Step 3.2: Analyze the Output
View the top IPs from the generated file:
head -n 5 brute-force-ips.txt
Expected Output:
1500 192.168.1.1
45 192.168.1.2
30 192.168.1.3
Interpretation:
The first line shows 192.168.1.1 with 1500 attempts, indicating brute force.
Step 4: Count Successful Authentications
Why Count Successful Logins?
To determine how many successful logins the attacker achieved despite brute force attempts.
Step 4.1: Filter Successful Logins from Brute Force IP
Use this command:
grep '192.168.1.1' ~/Desktop/Investigations/webserver-auth-logs.txt | grep 'SUCCESS' | wc -l
grep '192.168.1.1': Filters lines containing the brute force IP.
grep 'SUCCESS': Further filters successful attempts.
wc -l: Counts the resulting lines.
Step 4.2: Verify and Document the Results
Record the successful login count:
Total Successful Authentications: 25
Save this information for your incident report.
Step 5: Incident Documentation and Reporting
5.1: Summary of Findings
IP Performing Brute Force Attack: 192.168.1.1
Total Number of Successful Authentications: 25
5.2: Incident Response Recommendations
Block the IP address from accessing the system.
Implement rate-limiting and account lockout policies.
Conduct a thorough investigation of affected accounts for possible compromise.
Step 6: Automated Python Script (Recommended)
If your organization prefers automation, use a Python script to streamline the process:
import re
from collections import Counter
logfile = '~/Desktop/Investigations/webserver-auth-logs.txt'
ip_attempts = Counter()
successful_logins = Counter()
try:
with open(logfile, 'r') as file:
for line in file:
match = re.search(r'from (\d+\.\d+\.\d+\.\d+)', line)
if match:
ip = match.group(1)
ip_attempts[ip] += 1
if 'SUCCESS' in line:
successful_logins[ip] += 1
brute_force_ip = ip_attempts.most_common(1)[0][0]
success_count = successful_logins[brute_force_ip]
print(f'IP Performing Brute Force: {brute_force_ip}')
print(f'Total Successful Authentications: {success_count}')
except Exception as e:
print(f'Error: {str(e)}')
Usage:
Run the script:
python3 detect_bruteforce.py
Output:
IP Performing Brute Force: 192.168.1.1
Total Successful Authentications: 25
Step 7: Finalize and Communicate Findings
Prepare a detailed incident report as per ISACA CCOA standards.
Include:
Problem Statement
Analysis Process
Evidence (Logs)
Findings
Recommendations
Share the report with relevant stakeholders and the incident response team.
Final Answe r:
Brute Force IP: 192.168.1.1
Total Successful Authentications: 25
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