• “An accountant at your organization received an email regarding an invoice with a download link. Suspicious network traffic was observed shortly after opening the email. As a SOC analyst, investigate the network trace and analyze exfiltration attempts.”

Question 1

• “How many packets does the capture have?”

Answer: 4003

Question 2

• “At what time was the first packet captured?”

Answer: 2019-04-10 20:37

Question 3

• “What is the duration of the capture?”

Answer: 01:03:41

Question 4

• “What is the most active computer at the link level?”

• By going to Statistic > Conversations, the link with the most packets is 00:08:02:1c:47:ae

Question 5

• “Manufacturer of the NIC of the most active system at the link level?”

• A quick lookup using https://maclookup.app gives us the answer.

Answer: Hewlett-Packard

Question 6

• “Where is the headquarter of the company that manufactured the NIC of the most active computer at the link level?”

• A quick lookup on Wikipedia gives us the answer.

  

Answer: Palo Alto

Question 7

• “The organization works with private addressing and netmask /24. How many computers in the organization are involved in the capture?”

• A netmask of /24 means only the last portion of the IP address varies.
• Going to Statistic > Endpoint.

• This matches the private netmask /24 with 10.4.10.255 being a broadcast address with no sent packets.

Answer: 3

Question 8

• “What is the name of the most active computer at the network level?”

• The most active address is 10.4.10.132. So we will use that as our starting point.

• We can see a DHCP request made by 10.4.10.132 with the hostname as Beijing-5cd1-PC

Answer: Beijing-5cd1-PC

Question 9

• “What is the IP of the organization’s DNS server?”

• Filtering out DNS requests, we can see all DNS queries are sent to 10.4.10.4

Answer: 10.4.10.4

Question 10

• “What domain is the victim asking about in packet 204?”

Answer: proforma-invoices.com

Question 11

• “What is the IP of the domain in the previous question?”

• We can use the DNS response in frame 206 for this.

  

Answer: 217.182.138.150

Question 12

• “Indicate the country to which the IP in the previous section belongs.

• We can use whois to find the registration country.

$ whois '217.182.138.150' | grep 'country'
country: FR

Answer: France

Question 13

• “What operating system does the victim’s computer run?”

• We can filter out the HTTP requests and get the User-Agent of the victim.

Answer: Windows NT 6.1

Question 14

• “What is the name of the malicious file downloaded by the accountant?”

• Looking at the HTTP requests, the accountant’s computer made an HTTP request to http://proforma-invoices.com/proforma/tkraw_Protected99.exe

Question 15

• “What is the md5 hash of the downloaded file?”

• To calculate the MD5 hash of the file, we have to export it.

$ tshark -r stealer.pcap -Y 'frame.number == 3155' -T fields -e media.type | xxd -r -p > tkraw_Protected99.exe && md5sum tkraw_Protected99.exe
71826ba081e303866ce2a2534491a2f7  tkraw_Protected99.exe

Answer: 71826ba081e303866ce2a2534491a2f7

Question 16

• “What software runs the webserver that hosts the malware?”

• Looking at the server’s response give us the answer.

Answer: LiteSpeed

Question 17

• “What is the public IP of the victim’s computer?”

• After the response was made, the victim’s computer made a HTTP request to whatismyip.com – a public IP query webserver.

• Which responded in packet 3166.

Answer: 173.66.146.112

Question 18

• “In which country is the email server to which the stolen information is sent?”

• Filtering out the SMTP requests, we can see multiple email sent to macwinlogistics.in, which has the TLD of India.

  

• But a whois lookup on the SMTP server’s IP (23.229.162.69) tells us that this mailserver resides in the United States.

$ whois '23.229.162.69' | grep Country
Country:        US

Answer: United States

Question 19

• “Analyzing the first extraction of information. What software runs the email server to which the stolen data is sent?”

• Looking at the mailserver’s response code.

• The server seems to be running Exim.

Answer: Exim 4.91

Question 20

• “To which email account is the stolen information sent?”

• Looking at the content of each sent emails, we can see some sort of password exfiltration sent to the attacker.

  

Answer: [email protected]

Question 21

• “What is the password used by the malware to send the email?”

• By going into Tools > Credentials, we can see multiple SMTP authentications requests.

• Further inspection of one of these packets give us the password encoded in Base-64.

  

$ printf 'U2FsZXNAMjMM=' | base64 -d
Sales@23

Answer: Sales@23

Question 22

• “Which malware variant exfiltrated the data?”

• Looking at the exfiltrated data again.

  

• We can see that the password was exfiltrated by HawkEye Keylogger - Reborn v9.

Answer: Reborn v9

Question 23

• “What are the bankofamerica access credentials? (username:password)”

• Further inspection of the exfiltrated passwords give us the credentials.

Answer: roman.mcguire:P@ssw0rd$

Question 24

• “Every how many minutes does the collected data get exfiltrated?”

• By filtering out every emails sent to the same address.

• We can see that the data gets exfiltrated every 131 packets, with the Time delta from previous exfiltration attempt being 10 minutes and 4 seconds.

Answer: 10