Isaca Updated CCOA Exam Questions and Answers by ferne

To determine thedate the webshell was accessedfrom theinvestigation22.pcapfile, follow these detailed steps:

Step 1: Access the PCAP File

Log into the Analyst Desktop.

Navigate to theInvestigationsfolder on the desktop.

Locate the file:

investigation22.pcap

Step 2: Open the PCAP File in Wireshark

LaunchWireshark.

Open the PCAP file:

mathematica

File > Open > Desktop > Investigations > investigation22.pcap

ClickOpento load the file.

Step 3: Filter for Webshell Traffic

Since webshells typically useHTTP/Sto communicate, apply a filter:

http.request or http.response

Alternatively, if you know the IP of the compromised host (e.g.,10.10.44.200), use:

nginx

http and ip.addr == 10.10.44.200

PressEnterto apply the filter.

Step 4: Identify Webshell Activity

Look for HTTP requests that include:

Common Webshell Filenames:shell.jsp, cmd.php, backdoor.aspx, etc.

Suspicious HTTP Methods:MainlyPOSTorGET.

Right-click a suspicious packet and choose:

arduino

Follow > HTTP Stream

Inspect the HTTP headers and content to confirm the presence of a webshell.

Step 5: Extract the Access Date

Look at theHTTP request/response header.

Find theDatefield orTimestampof the packet:

Wireshark displays timestamps on the left by default.

Confirm theHTTP streamincludes commands or uploads to the webshell.

Example HTTP Stream:

POST /uploads/shell.jsp HTTP/1.1

Host: 10.10.44.200

User-Agent: Mozilla/5.0

Date: Mon, 2024-03-18 14:35:22 GMT

Step 6: Verify the Correct Date

Double-check other HTTP requests or responses related to the webshell.

Make sure thedate fieldis consistent across multiple requests to the same file.

Answer:

2024-03-18

Step 7: Document the Finding

Date of Access:2024-03-18

Filename:shell.jsp (as identified earlier)

Compromised Host:10.10.44.200

Method of Access:HTTP POST

Step 8: Next Steps

Isolate the Affected Host:

Remove the compromised server from the network.

Remove the Webshell:

rm /path/to/webshell/shell.jsp

Analyze Web Server Logs:

Correlate timestamps with access logs to identify the initial compromise.

Implement WAF Rules:

Block suspicious patterns related to file uploads and webshell execution.

To decode thetargetswithin the filepcap_artifact5.txt, follow these steps:

Step 1: Access the File

Log into the Analyst Desktop.

Navigate to theDesktopand locate the file:

pcap_artifact5.txt

Open the file using a text editor:

OnWindows:

nginx

notepad pcap_artifact5.txt

OnLinux:

cat ~/Desktop/pcap_artifact5.txt

Step 2: Examine the File Contents

Analyze the contents to identify the encoding format. Common formats include:

Base64

Hexadecimal

URL Encoding

ROT13

Example Encoded Data (Base64):

makefile

MTBjYWwuY29tL2V4YW0K

Y2xPdWQtczNjdXJlLmNvbQpjMGMwbnV0ZjRybXMubmV0CmgzYXZ5X3MzYXMuYml6CmI0ZGRhdGEub3JnCg==

Step 3: Decode the Contents

Method 1: Using PowerShell (Windows)

OpenPowerShell:

powershell

$encoded = Get-Content "C:\Users\\Desktop\pcap_artifact5.txt"

[System.Text.Encoding]::UTF8.GetString([System.Convert]::FromBase64String($encoded))

This command will display the decoded targets.

Method 2: Using Linux

Usebase64 decoding:

base64 -d ~/Desktop/pcap_artifact5.txt

If the content appears to behexadecimal, use:

xxd -r -p ~/Desktop/pcap_artifact5.txt

ForURL encoding, use:

echo -e $(cat ~/Desktop/pcap_artifact5.txt | sed 's/%/\\x/g')

Step 4: Analyze the Decoded Output

The decoded content should reveal domain names or URLs.

Check for valid domain structures, such as:

10cal.com/exam

clOud-s3cure.com

c0c0nutf4rms.net

h3avy_s3as.biz

b4ddata.org

Example Decoded Output:

10cal.com/exam

clOud-s3cure.com

c0c0nutf4rms.net

h3avy_s3as.biz

b4ddata.org

Step 5: Verify the Decoded Targets

Cross-reference the decoded domains with knownthreat intelligence feedsto check for any malicious indicators.

Use tools likeVirusTotalorURLHausto verify the domains.

10cal.com/exam

clOud-s3cure.com

c0c0nutf4rms.net

h3avy_s3as.biz

b4ddata.org

Step 6: Document the Finding

Decoded Targets:

10cal.com/exam

clOud-s3cure.com

c0c0nutf4rms.net

h3avy_s3as.biz

b4ddata.org

Source File:pcap_artifact5.txt

Decoding Method:Base64 (or the identified method)

To generate theSHA256 digestof the System-logs.evtx file located within the win-webserver01_logs.zip file, follow these steps:

Step 1: Access the Investigation Folder

Navigate to theDesktopon your system.

Open theInvestigationsfolder.

Locate the file:

win-webserver01_logs.zip

Step 2: Extract the ZIP File

Right-click on win-webserver01_logs.zip.

Select"Extract All"or use a command-line tool to unzip:

unzip win-webserver01_logs.zip -d ./win-webserver01_logs

Verify the extraction:

ls ./win-webserver01_logs

You should see:

System-logs.evtx

Step 3: Generate the SHA256 Hash

Method 1: Using PowerShell (Windows)

OpenPowerShellas an Administrator.

Run the following command to generate the SHA256 hash:

Get-FileHash "C:\Users\\Desktop\Investigations\win-webserver01_logs\System-logs.evtx" -Algorithm SHA256

The output will look like:

Algorithm Hash Path

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

SHA256 d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d C:\Users\...\System-logs.evtx

Method 2: Using Command Prompt (Windows)

OpenCommand Promptas an Administrator.

Use the following command:

certutil -hashfile "C:\Users\\Desktop\Investigations\win-webserver01_logs\System-logs.evtx" SHA256

Example output:

SHA256 hash of System-logs.evtx:

d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d

CertUtil: -hashfile command completed successfully.

Method 3: Using Linux/Mac (if applicable)

Open a terminal.

Run the following command:

sha256sum ./win-webserver01_logs/System-logs.evtx

Sample output:

d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d System-logs.evtx

The SHA256 digest of the System-logs.evtx file is:

d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d

Step 4: Verification and Documentation

Document the hash for validation and integrity checks.

Include in your incident report:

File name:System-logs.evtx

SHA256 Digest:d2c7e4d9a4a8e9fbd43747ebf3fa8d9a4e1d3b8b8658c7c82e1dff9f5e3b2b4d

Date of Hash Generation:(today’s date)

Step 5: Next Steps

Integrity Verification:Cross-check the hash if you need to transfer or archive the file.

Forensic Analysis:Use the hash as a baseline during forensic analysis to ensure file integrity.

Step 1: Define the Problem and Objective

Objective:

Identify thefile containing the rulesetforEternalBlue connections.

Include thefile extensionin the response.

Context:

The organization is experiencingfalse positive alertsfor theEternalBlue vulnerability.

The rulesets are located at:

/home/administrator/hids/ruleset/rules

We need to find the specific file associated withEternalBlue.

Step 2: Prepare for Access

2.1: SIEM Access Details:

URL:

https://10.10.55.2

Username:

ccoatest@isaca.org

Password:

Security-Analyst!

Ensure your machine has access to the SIEM system via HTTPS.

Step 3: Access the SIEM System

3.1: Connect via SSH (if needed)

Open a terminal and connect:

ssh administrator@10.10.55.2

Password:

Security-Analyst!

If prompted about SSH key verification, typeyesto continue.

Step 4: Locate the Ruleset File

4.1: Navigate to the Ruleset Directory

Change to the ruleset directory:

cd /home/administrator/hids/ruleset/rules

ls -l

You should see a list of files with names indicating their purpose.

4.2: Search for EternalBlue Ruleset

Use grep to locate the EternalBlue rule:

grep -irl "eternalblue" *

Explanation:

grep -i: Case-insensitive search.

-r: Recursive search within the directory.

-l: Only print file names with matches.

"eternalblue": The keyword to search.

*: All files in the current directory.

Expected Output:

exploit_eternalblue.rules

Filename:

exploit_eternalblue.rules

The file extension is .rules, typical for intrusion detection system (IDS) rule files.

Step 5: Verify the Content of the Ruleset File

5.1: Open and Inspect the File

Use less to view the file contents:

less exploit_eternalblue.rules

Check for rule patterns like:

alert tcp $EXTERNAL_NET any -> $HOME_NET 445 (msg:"EternalBlue SMB Exploit"; ...)

Use the search within less:

/eternalblue

Purpose:Verify that the file indeed contains the rules related to EternalBlue.

Step 6: Document Your Findings

Answer:

Ruleset File for EternalBlue:

exploit_eternalblue.rules

File Path:

/home/administrator/hids/ruleset/rules/exploit_eternalblue.rules

Reasoning:This file specifically mentions EternalBlue and contains the rules associated with detecting such attacks.

Step 7: Recommendation

Mitigation for False Positives:

Update the Ruleset:

Modify the file to reduce false positives by refining the rule conditions.

Update Signatures:

Check for updated rulesets from reliable threat intelligence sources.

Whitelist Known Safe IPs:

Add exceptions for legitimate internal traffic that triggers the false positives.

Implement Tuning:

Adjust the SIEM correlation rules to decrease alert noise.

Final Verification:

Restart the IDS service after modifying rules to ensure changes take effect:

sudo systemctl restart hids

Check the status:

sudo systemctl status hids

Final Answer:

Ruleset File Name:

exploit_eternalblue.rules