Blue is a Windows based box at which has an easy rating.

Starting with Enumeration we find it looks to be a pretty vanilla Windows 7 installation.

# Nmap 7.70 scan initiated Fri Mar  1 18:25:52 2019 as: nmap -sV --script=default,vuln -p- -oA Blue
Nmap scan report for
Host is up (0.19s latency).
Not shown: 65527 closed ports
135/tcp   open  msrpc        Microsoft Windows RPC
445/tcp   open  microsoft-ds Windows 7 Professional 7601 Service Pack 1 microsoft-ds (workgroup: WORKGROUP)
49152/tcp open  msrpc        Microsoft Windows RPC
49153/tcp open  msrpc        Microsoft Windows RPC
49154/tcp open  msrpc        Microsoft Windows RPC
49155/tcp open  msrpc        Microsoft Windows RPC
49156/tcp open  msrpc        Microsoft Windows RPC
49157/tcp open  msrpc        Microsoft Windows RPC
Service Info: Host: HARIS-PC; OS: Windows; CPE: cpe:/o:microsoft:windows

Host script results:
|_clock-skew: mean: -8m09s, deviation: 4s, median: -8m12s
| smb-os-discovery: 
|   OS: Windows 7 Professional 7601 Service Pack 1 (Windows 7 Professional 6.1)
|   OS CPE: cpe:/o:microsoft:windows_7::sp1:professional
|   Computer name: haris-PC
|   NetBIOS computer name: HARIS-PC\x00
|   Workgroup: WORKGROUP\x00
|_  System time: 2019-03-01T23:28:18+00:00
| smb-security-mode: 
|   account_used: guest
|   authentication_level: user
|   challenge_response: supported
|_  message_signing: disabled (dangerous, but default)
|_smb-vuln-ms10-054: false
|_smb-vuln-ms10-061: NT_STATUS_OBJECT_NAME_NOT_FOUND
| smb-vuln-ms17-010: 
|   Remote Code Execution vulnerability in Microsoft SMBv1 servers (ms17-010)
|     State: VULNERABLE
|     IDs:  CVE:CVE-2017-0143
|     Risk factor: HIGH
|       A critical remote code execution vulnerability exists in Microsoft SMBv1
|        servers (ms17-010).
|     Disclosure date: 2017-03-14
|     References:
| smb2-security-mode: 
|   2.02: 
|_    Message signing enabled but not required
| smb2-time: 
|   date: 2019-03-01 18:28:13
|_  start_date: 2019-02-26 15:50:18

Service detection performed. Please report any incorrect results at .
# Nmap done at Fri Mar  1 18:36:50 2019 -- 1 IP address (1 host up) scanned in 657.69 seconds

Based on the above results - MS17-010 looks like a good candidate to start with. Metasploit could be used, but in this case we can do it manually using the AutoBlue exploit code found on GitHub -

The Exploit code has some instructions to follow - Shellcode needs to be generated and added to a binary. This is all done with a provided script.

Before running the exploit, make sure to start a netcat listener on the ports you selected. You may need to run the exploit a couple of times for it to work.

Once run you should end up with a system shell

From this point, you can get the root and user flags.