CCOA Practice Questions

Step 1: Define the Problem and Objective

Objective:

We need to identify the following from the webserver-auth-logs.txt file:

TheIP address performing a brute force attack.

Thetotal number of successful authenticationsmade 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:

Multiplelogin attemptsfrom thesame IP.

Combination ofFAILUREandSUCCESSmessages.

High volumeof 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

Explanation:

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

Explanation:

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 addressfrom accessing the system.

Implementrate-limiting and account lockout policies.

Conduct athorough investigationof 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 Answer:

Brute Force IP:192.168.1.1

Total Successful Authentications:25

To identify thefile namethat triggered theRuleName: Suspicious PowerShellon theaccounting-pcworkstation, follow these detailed steps:

Step 1: Access the SIEM System

Open your web browser and navigate to theSIEM dashboard.

Log in with youradministrator credentials.

Step 2: Set Up the Query

Go to theSearchorQuerysection of the SIEM.

Set theTime Rangeto thelast 24 hours.

Query Parameters:

Agent Name:accounting-pc

Rule Name:Suspicious PowerShell

Event Type:Startup items or Process creation

Step 3: Construct the SIEM Query

Here’s an example of how to construct the query:

Example Query (Splunk):

index=windows_logs

| search agent.name="accounting-pc" RuleName="Suspicious PowerShell"

| where _time > now() - 24h

| table _time, agent.name, process_name, file_path, RuleName

Example Query (Elastic SIEM):

{

"query": {

"bool": {

"must": [

{ "match": { "agent.name": "accounting-pc" }},

{ "match": { "RuleName": "Suspicious PowerShell" }},

{ "range": { "@timestamp": { "gte": "now-24h" }}}

]

}

}

}

Step 4: Analyze the Query Results

The query should return a table or list containing:

Time of Execution

Agent Name:accounting-pc

Process Name

File Path

Rule Name

Example Output:

_time

agent.name

process_name

file_path

RuleName

2024-04-07T10:45:23

accounting-pc

powershell.exe

C:\Users\Accounting\AppData\Roaming\calc.ps1

Suspicious PowerShell

Step 5: Identify the Suspicious File

Theprocess_namein the output showspowershell.exeexecuting a suspicious script.

Thefile pathindicates the script responsible:

makefile

C:\Users\Accounting\AppData\Roaming\calc.ps1

The suspicious script file is:

calc.ps1

Step 6: Confirm the Malicious Nature

Manual Inspection:

Navigate to the specified file path on theaccounting-pcworkstation.

Check the contents of calc.ps1 for any malicious PowerShell code.

Hash Verification:

Generate theSHA256 hashof the file and compare it with known malware signatures.

Answer:

calc.ps1

Step 7: Immediate Response

Isolate the Workstation:Disconnectaccounting-pcfrom the network.

Terminate the Malicious Process:

Stop the powershell.exe process running calc.ps1.

Use Task Manager or a script:

powershell

Stop-Process -Name "powershell" -Force

Remove the Malicious Script:

powershell

Remove-Item "C:\Users\Accounting\AppData\Roaming\calc.ps1" -Force

Scan for Persistence Mechanisms:

CheckStartup itemsandScheduled Tasksfor any references to calc.ps1.

Step 8: Documentation

Record the following:

Date and Time:When the incident was detected.

Affected Host:accounting-pc

Malicious File:calc.ps1

Actions Taken:File removal and process termination.

To generate theSHA256 checksumof the file that triggeredRuleName: Suspicious PowerShellon theAccounting workstation, follow these detailed steps:

Step 1: Establish an SSH Connection

Open a terminal on your system.

Use the provided credentials to connect to theAccounting workstation:

ssh Accounting@

Replace with the actual IP address of the workstation.

Enter the password when prompted:

1x-4cc0unt1NG-x1

Step 2: Locate the Malicious File

Navigate to the typical directory where suspicious scripts are stored:

cd C:\Users\Accounting\AppData\Roaming

List the contents to identify the suspicious file:

dir

Look for a file related toPowerShell(e.g., calc.ps1), as the issue involved thecalculator opening repeatedly.

Step 3: Verify the Malicious File

To ensure it is the problematic file, check for recent modifications:

powershell

Get-ChildItem -Path "C:\Users\Accounting\AppData\Roaming" -Recurse | Where-Object { $_.LastWriteTime -ge (Get-Date).AddDays(-1) }

This will list files modified within the last 24 hours.

Check file properties:

powershell

Get-Item "C:\Users\Accounting\AppData\Roaming\calc.ps1" | Format-List *

Confirm it matches the file flagged byRuleName: Suspicious PowerShell.

Step 4: Generate the SHA256 Checksum

Method 1: Using PowerShell (Recommended)

Run the following command to generate the hash:

powershell

Get-FileHash "C:\Users\Accounting\AppData\Roaming\calc.ps1" -Algorithm SHA256

Output Example:

mathematica

Algorithm Hash Path

--------- ---- ----

SHA256 d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d C:\Users\Accounting\AppData\Roaming\calc.ps1

Method 2: Using certutil (Alternative)

Run the following command:

cmd

certutil -hashfile "C:\Users\Accounting\AppData\Roaming\calc.ps1" SHA256

Example Output:

SHA256 hash of calc.ps1:

d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d

CertUtil: -hashfile command completed successfully.

Step 5: Copy and Paste the Hash

Copy theSHA256 hashfrom the output and paste it as required.

Answer:

nginx

d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d

Step 6: Immediate Actions

Terminate the Malicious Process:

powershell

Stop-Process -Name "powershell" -Force

Delete the Malicious File:

powershell

Remove-Item "C:\Users\Accounting\AppData\Roaming\calc.ps1" -Force

Disable Startup Entry:

Check for any persistent scripts:

powershell

Get-ItemProperty -Path "HKCU:\Software\Microsoft\Windows\CurrentVersion\Run"

Remove any entries related to calc.ps1.

Step 7: Document the Incident

Record the following:

Filename:calc.ps1

File Path:C:\Users\Accounting\AppData\Roaming\

SHA256 Hash:d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d

Date of Detection:(Today’s date)