techniques against web anti-automatization bruno ramos brunolcr@yahoo.com.br h2hc ii - 2005
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Techniques against Techniques against Web Anti-Web Anti-
AutomatizationAutomatization
Bruno RamosBruno Ramos
brunolcr@yahoo.com.brbrunolcr@yahoo.com.br
H2HC II - 2005H2HC II - 2005
SummarySummary
ObjectivesObjectives Automatization x Anti-Automatization x Anti-
AutomatizationAutomatization Dog_Crawler x PHP_GUARDDog_Crawler x PHP_GUARD ConclusionConclusion DEMODEMO
ObjectivesObjectives
To present a new seek area on Web To present a new seek area on Web HackingHacking
Performance in the automatization Performance in the automatization processprocess
To generate new ideas of techniques To generate new ideas of techniques against anti-automatizationagainst anti-automatization
Automatization x Anti-Automatization x Anti-AutomatizationAutomatization
AutomatizationAutomatization Automatized SweepingsAutomatized Sweepings
What he is an automatized sweeper?What he is an automatized sweeper? Development of the automatized sweepingsDevelopment of the automatized sweepings Class of automatization toolsClass of automatization tools
Vulnerabilities TechniquesVulnerabilities Techniques Anti-AutomatizationAnti-Automatization
– Main used techniquesMain used techniques
AutomatizationAutomatization
ObjectiveObjective PrinciplesPrinciples
– CodificationCodification– AlgorithmsAlgorithms– ProcessProcess
Automatized SweepingsAutomatized Sweepings
What he is an automatized sweeper? What he is an automatized sweeper? – MirroringMirroring
The Robbery of copyrightThe Robbery of copyright Part of one has attacked of main-in-the-middlePart of one has attacked of main-in-the-middle
– SpideringSpidering Harvest of email for Spam listHarvest of email for Spam list Attack of social engineering on personal datasAttack of social engineering on personal datas To understand development techniquesTo understand development techniques To discover details of the application for exploration To discover details of the application for exploration
phasephase Map the structure of the applicationMap the structure of the application
– CGI ScanningCGI Scanning Probable administrative pages and Probable administrative pages and
directoriesdirectories Localization of archives and common Localization of archives and common
directoriesdirectories
– Brute ForcingBrute Forcing Based in dictionaryBased in dictionary List of archives and common directoriesList of archives and common directories Incremental Interaction on all the possible Incremental Interaction on all the possible
characterscharacters
Automatized SweepingsAutomatized Sweepings
– FuzzingFuzzing Buffer OverflowsBuffer Overflows Cross-site scriptingCross-site scripting SQL InjectionSQL Injection Difference enters the process of validation of Difference enters the process of validation of
client-side and server-sideclient-side and server-side
Automatized SweepingsAutomatized Sweepings
Development of the automatized sweepingsDevelopment of the automatized sweepings– 1 Generation 1 Generation
CGI scannersCGI scanners
– 2 Generation2 Generation SpideringSpidering MirroringMirroring Brute forcingBrute forcing
– 3 Generation3 Generation FuzzingFuzzing
– 4 Generation4 Generation Anti-Automatization? Anti-Automatization?
Automatized SweepingsAutomatized Sweepings
Class of automatization toolsClass of automatization tools– Web SpiderWeb Spider– CGI ScannerCGI Scanner– Brute ForceBrute Force– FuzzerFuzzer– Vulnerability ScannersVulnerability Scanners
Automatized SweepingsAutomatized Sweepings
Vulnerabilities TechniquesVulnerabilities Techniques
OWASP Top Ten Most Critical Web OWASP Top Ten Most Critical Web Application Security VulnerabilitiesApplication Security Vulnerabilities– Unvalidated Input Unvalidated Input – Broken Access ControlBroken Access Control– Broken Authentication and Session ManagementBroken Authentication and Session Management– Cross Site Scripting (XSS) FlawsCross Site Scripting (XSS) Flaws– Buffer OverflowsBuffer Overflows– Injection FlawsInjection Flaws– Improper Error HandlingImproper Error Handling – Insecure StorageInsecure Storage – Denial of ServiceDenial of Service– Insecure Configuration ManagementInsecure Configuration Management
Anti-AutomatizationAnti-Automatization
Blocking of HEAD requestsBlocking of HEAD requests Content-Type ManipulationContent-Type Manipulation HTTP Status CodesHTTP Status Codes Thresholds and TimeoutsThresholds and Timeouts Honeypot linksHoneypot links
Blocking of HEAD requestsBlocking of HEAD requests
Easy to implementEasy to implement Low ImpactLow Impact Used against:Used against:
1 Generation CGI Scanners1 Generation CGI Scanners 1 Generation Web Spiders1 Generation Web Spiders 1 Generation Fuzzers1 Generation Fuzzers
Content-Type ManipulationContent-Type Manipulation
Configuration in the ServerConfiguration in the Server Codification in the applicationCodification in the application Used against:Used against:
Mirroring SoftwareMirroring Software Web SpidersWeb Spiders 1 Generation vulnerability scanners1 Generation vulnerability scanners
HTTP Status CodesHTTP Status Codes
SimplicitySimplicity Control of the development Control of the development Used against:Used against:
FuzzersFuzzers Brute ForcersBrute Forcers CGI ScannersCGI Scanners Vulnerability ScannersVulnerability Scanners
Thresholds and TimeoutsThresholds and Timeouts
Frequency of solicitationsFrequency of solicitations Multiple solicitations Multiple solicitations Used against:Used against:
Web SpidersWeb Spiders Brute ForcersBrute Forcers CGI ScannersCGI Scanners Vulnerability ScannersVulnerability Scanners
Honeypot LinksHoneypot Links
Simple ConfigurationSimple Configuration Customizadas answersCustomizadas answers Used against:Used against:
Web SpidersWeb Spiders Mirroring SoftwareMirroring Software
Dog_Crawler x PHP_GUARDDog_Crawler x PHP_GUARD PHP_GUARDPHP_GUARD
Archetype to defeat the mechanism of Crawler? Archetype to defeat the mechanism of Crawler? Easily incorporated in an applicationEasily incorporated in an application Author: “Web Hacking – Attacks and Defense”Author: “Web Hacking – Attacks and Defense”
DOG_CrawlerDOG_Crawler Crawler with support the techniques against anti-Crawler with support the techniques against anti-
AutomatizationAutomatization Project in development that it needs new crazy ideas to Project in development that it needs new crazy ideas to
break others anti-automatization techniquesbreak others anti-automatization techniques Implemented using PerlImplemented using Perl It uses the mechanism of crawler of the LibwhiskerIt uses the mechanism of crawler of the Libwhisker
PHP_GUARD PHP_GUARD
TechniquesTechniques Enforces Strict Session ControlEnforces Strict Session Control Varying HTTP Response CodesVarying HTTP Response Codes Structurally Different HTML all the TimeStructurally Different HTML all the Time Generates Random HyperlinksGenerates Random Hyperlinks Generates Random HTML Authentication Generates Random HTML Authentication
FormsForms Ability to Slow Down Response Ability to Slow Down Response
Enforces Strict Session Enforces Strict Session ControlControl
set_session.phpset_session.php
<?php<?php
// begin a session// begin a session
session_start();session_start();
$_SESSION['begin'] = 1;$_SESSION['begin'] = 1;
?>?>
php_guard.phpphp_guard.php
// check the session status// check the session status
......
session_start();session_start();
if(!isset($_SESSION['begin'])) {if(!isset($_SESSION['begin'])) {
header("Location: /"); header("Location: /"); setcookie(session_name(), "", 0, "/"); setcookie(session_name(), "", 0, "/");
session_destroy();session_destroy();
exit;exit;
}}
......
Varying HTTP Response Varying HTTP Response Codes Codes
php_guard.phpphp_guard.php
$dice = mt_rand(1, 100);$dice = mt_rand(1, 100);
if($dice < $SG_404_PROBABILITY) {if($dice < $SG_404_PROBABILITY) {
response_404();response_404();
}}
else {else {
$dice = mt_rand(1, 100);$dice = mt_rand(1, 100);
if($dice < $SG_302_PROBABILITY) {if($dice < $SG_302_PROBABILITY) {
response_302();response_302();
}}
else {else {
response_200();response_200();
}}
}}
php_guard.phpphp_guard.php
function load_quote_array() {function load_quote_array() {
global $SG_QUOTE_ARRAY, global $SG_QUOTE_ARRAY, $SG_QUOTES_FILE, $DEBUG;$SG_QUOTES_FILE, $DEBUG;
static $quote_array, $flag = 0;static $quote_array, $flag = 0;
if(!$flag) {if(!$flag) {
$quote_array = $quote_array = file($SG_QUOTES_FILE);file($SG_QUOTES_FILE);
$flag = 1;$flag = 1;
}}
$SG_QUOTE_ARRAY = $quote_array;$SG_QUOTE_ARRAY = $quote_array;
}}
Varying HTTP Response Varying HTTP Response Codes Codes
php_guard.phpphp_guard.php
function response_404() {function response_404() {
header("HTTP/1.0 404 Not Found");header("HTTP/1.0 404 Not Found");
echo("<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n");echo("<!DOCTYPE HTML PUBLIC \"-//IETF//DTD HTML 2.0//EN\">\n");
echo("<html><head>\n");echo("<html><head>\n");
echo("<title>404 Not Found</title>\n");echo("<title>404 Not Found</title>\n");
echo("</head><body>\n");echo("</head><body>\n");
echo("<h1>Not Found</h1>\n");echo("<h1>Not Found</h1>\n");
echo("<p>The requested URL " . echo("<p>The requested URL " .
..
..
..
Varying HTTP Response Varying HTTP Response Codes Codes
php_guard.phpphp_guard.php
function response_302() {function response_302() {
global $SG_QUOTE_ARRAY;global $SG_QUOTE_ARRAY;
$link = random_link($SG_QUOTE_ARRAY, "/");$link = random_link($SG_QUOTE_ARRAY, "/");
header("Location: " . $link);header("Location: " . $link);
}}
function random_link(&$list, $prefix) {function random_link(&$list, $prefix) {
$result = random_directory($list, $prefix) . random_word($list);$result = random_directory($list, $prefix) . random_word($list);
$result = random_extension($result);$result = random_extension($result);
$result .= random_querystring($list);$result .= random_querystring($list);
return($result);return($result);
}}
Structurally Differrent HTML Structurally Differrent HTML all the Timeall the Time
php_guard.phpphp_guard.php
function response_200() {function response_200() {
global $SG_QUOTE_ARRAY, $SG_OPENING_HTML, global $SG_QUOTE_ARRAY, $SG_OPENING_HTML, $SG_CLOSING_HTML;$SG_CLOSING_HTML;
global $SG_MAX_TEXT_LIMIT, global $SG_MAX_TEXT_LIMIT, $SG_MIN_TEXT_LIMIT;$SG_MIN_TEXT_LIMIT;
header("HTTP/1.0 200 OK");header("HTTP/1.0 200 OK");
// see how many quotes we have// see how many quotes we have
$quote_count = count($SG_QUOTE_ARRAY);$quote_count = count($SG_QUOTE_ARRAY);
// generate a random number// generate a random number
$limit = $quote_count;$limit = $quote_count;
if($limit > $SG_MAX_TEXT_LIMIT) {if($limit > $SG_MAX_TEXT_LIMIT) {
$limit = $SG_MAX_TEXT_LIMIT;$limit = $SG_MAX_TEXT_LIMIT;
}}
$random_number = $random_number = mt_rand($SG_MIN_TEXT_LIMIT, $limit);mt_rand($SG_MIN_TEXT_LIMIT, $limit);
// decide the HTML text containers// decide the HTML text containers
$opening_html = $SG_OPENING_HTML;$opening_html = $SG_OPENING_HTML;
$closing_html = $SG_CLOSING_HTML;$closing_html = $SG_CLOSING_HTML;
$rand_html = array_rand($opening_html, 1);$rand_html = array_rand($opening_html, 1);
$opening_format = $opening_html[$rand_html];$opening_format = $opening_html[$rand_html];
$closing_format = $closing_html[$rand_html];$closing_format = $closing_html[$rand_html];
$opening_block = "";$opening_block = "";
$closing_block = "";$closing_block = "";
// decide if we want to do HTML tables or not// decide if we want to do HTML tables or not
// 50% chance for throwing in tables.// 50% chance for throwing in tables.
$table_flag = mt_rand(0, 1);$table_flag = mt_rand(0, 1);
if($table_flag) if($table_flag)
$opening_block = "<TABLE>";$opening_block = "<TABLE>";
$closing_block = "</TABLE>";$closing_block = "</TABLE>";
$opening_format = "<TR><TD>";$opening_format = "<TR><TD>";
$closing_format = "</TD></TR>";$closing_format = "</TD></TR>";
}}
$form_flag = 0;$form_flag = 0; // 50% chance of throwing in an HTML form// 50% chance of throwing in an HTML form $print_form = mt_rand(0, 1);$print_form = mt_rand(0, 1);
$rand_keys = $rand_keys = array_rand($SG_QUOTE_ARRAY, array_rand($SG_QUOTE_ARRAY, $random_number);$random_number); $form_loc = mt_rand(0, count($rand_keys));$form_loc = mt_rand(0, count($rand_keys)); echo($opening_block . "\n");echo($opening_block . "\n"); for($i = 0; $i < count($rand_keys); $i++) {for($i = 0; $i < count($rand_keys); $i++) { echo($opening_format);echo($opening_format);
echo(quote_parse($SG_QUOTE_ARRAY[echo(quote_parse($SG_QUOTE_ARRAY[$rand_keys[$i]]));$rand_keys[$i]])); if($print_form && !$form_flag && $i == if($print_form && !$form_flag && $i == $form_loc) {$form_loc) { random_auth_form();random_auth_form(); $form_flag = 1;$form_flag = 1; }} echo($closing_format . "\n");echo($closing_format . "\n"); }} echo($closing_block . "\n");echo($closing_block . "\n");}}
Structurally Differrent HTML Structurally Differrent HTML all the Timeall the Time
Generates Random Generates Random HyperlinksHyperlinks
php_guard.phpphp_guard.php
function random_link(&$list, $prefix) {function random_link(&$list, $prefix) {
$result = random_directory($list, $prefix) . $result = random_directory($list, $prefix) . random_word($list);random_word($list);
$result = random_extension($result);$result = random_extension($result);
$result .= random_querystring($list);$result .= random_querystring($list);
return($result);return($result);
}}
Generates Random Generates Random HyperlinksHyperlinks
php_guard.phpphp_guard.php
function random_directory(&$list, $prefix) {function random_directory(&$list, $prefix) {
global $SG_DIR_NAMES, $SG_FAKE_DIR_LEVEL;global $SG_DIR_NAMES, $SG_FAKE_DIR_LEVEL;
$dir_names = $SG_DIR_NAMES;$dir_names = $SG_DIR_NAMES;
$dir_prefix = array("", "/", "../");$dir_prefix = array("", "/", "../");
// levels of directories// levels of directories
$num_dirs = mt_rand(0, $SG_FAKE_DIR_LEVEL);$num_dirs = mt_rand(0, $SG_FAKE_DIR_LEVEL);
// generate an absolute or a relative prefix// generate an absolute or a relative prefix
if($prefix == "") {if($prefix == "") {
$rand_key = array_rand($dir_prefix, 1);$rand_key = array_rand($dir_prefix, 1);
$result = $dir_prefix[$rand_key];$result = $dir_prefix[$rand_key];
} else {} else {
$result = $prefix;$result = $prefix;
}}
for($i = 0; $i < $num_dirs; $i++) {for($i = 0; $i < $num_dirs; $i++) { if(mt_rand(0, 1)) {if(mt_rand(0, 1)) { $dir = random_word($list) . "/";$dir = random_word($list) . "/"; }} else {else { $rand_key = array_rand($dir_names, $rand_key = array_rand($dir_names, 1);1); $dir = $dir_names[$rand_key];$dir = $dir_names[$rand_key]; }} $result .= $dir;$result .= $dir; }} return($result);return($result);}}
Generates Random Generates Random HyperlinksHyperlinks
php_guard.phpphp_guard.php
function random_extension($str)function random_extension($str)
{{
global $SG_EXT_ARRAY;global $SG_EXT_ARRAY;
$ext_array = $SG_EXT_ARRAY;$ext_array = $SG_EXT_ARRAY;
$rand_key = array_rand($ext_array, 1);$rand_key = array_rand($ext_array, 1);
$result = $str . $ext_array[$rand_key];$result = $str . $ext_array[$rand_key];
return($result);return($result);
}}
Generates Random Generates Random HyperlinksHyperlinks
php_guard.phpphp_guard.php
function random_querystring(&$list)function random_querystring(&$list)
{{
global $SG_QUERY_INTEGERS, global $SG_QUERY_INTEGERS, $SG_QUERY_PATHS, $SG_PATH_PREFIXES;$SG_QUERY_PATHS, $SG_PATH_PREFIXES;
global $SG_QUERYSTRING_PARAMS;global $SG_QUERYSTRING_PARAMS;
$query_integers = $SG_QUERY_INTEGERS;$query_integers = $SG_QUERY_INTEGERS;
$query_paths = $SG_QUERY_PATHS;$query_paths = $SG_QUERY_PATHS;
$path_prefixes = $SG_PATH_PREFIXES;$path_prefixes = $SG_PATH_PREFIXES;
// let's decide if we want query strings or not// let's decide if we want query strings or not
$querystring = mt_rand(0, 1);$querystring = mt_rand(0, 1);
$result = "";$result = "";
if($querystring) {if($querystring) {
$result = "?";$result = "?";
// let's generate how many query string params do we want// let's generate how many query string params do we want $params = mt_rand(1, $SG_QUERYSTRING_PARAMS);$params = mt_rand(1, $SG_QUERYSTRING_PARAMS); $flag = 0;$flag = 0; for($i = 0; $i < $params; $i++) {for($i = 0; $i < $params; $i++) { // decide whether we want an integer, path, or a random // decide whether we want an integer, path, or a random wordword $type = mt_rand(1, 3);$type = mt_rand(1, 3); if($type == 1) {if($type == 1) { // choose a random integer// choose a random integer $rand_key = array_rand($query_integers, 1);$rand_key = array_rand($query_integers, 1); $param_name = $query_integers[$rand_key];$param_name = $query_integers[$rand_key]; $param_value = mt_rand(0, 65535);$param_value = mt_rand(0, 65535);
}} else {else { if($type == 2) {if($type == 2) { // generate a file path// generate a file path $rand_key = array_rand($query_paths, 1);$rand_key = array_rand($query_paths, 1); $param_name = $query_paths[$rand_key];$param_name = $query_paths[$rand_key]; $rand_key = array_rand($path_prefixes, 1);$rand_key = array_rand($path_prefixes, 1); $param_value = $path_prefixes[$rand_key];$param_value = $path_prefixes[$rand_key]; $param_value = $param_value . random_word($list);$param_value = $param_value . random_word($list);}}
$param_value = random_extension($param_value);$param_value = random_extension($param_value); }} else {else { // choose a random word// choose a random word $param_name = random_word($list);$param_name = random_word($list); if(mt_rand(0, 1)) {if(mt_rand(0, 1)) { $param_value = mt_rand(0, 65535);$param_value = mt_rand(0, 65535); }} else {else { $param_value = random_word($list);$param_value = random_word($list); }} }} }} if(!$flag) {if(!$flag) { $result .= $param_name . "=" . $param_value;$result .= $param_name . "=" . $param_value; $flag = 1;$flag = 1; }} else {else { $result .= "&" . $param_name . "=" . $param_value;$result .= "&" . $param_name . "=" . $param_value; }} }} }} return($result);return($result);
Generates Random Generates Random HyperlinksHyperlinks
function random_word(&$list)function random_word(&$list){{ $rand_key = array_rand($list, 1);$rand_key = array_rand($list, 1); $words = explode(" ", $list[$rand_key]);$words = explode(" ", $list[$rand_key]); $rand_key = array_rand($words, 1);$rand_key = array_rand($words, 1); $word = sanitize_alnum($words[$rand_key]);$word = sanitize_alnum($words[$rand_key]); return($word);return($word);}}
Generates Random HTML Generates Random HTML Authentication FormsAuthentication Forms
php_guard.phpphp_guard.php
function random_auth_form() {function random_auth_form() {
global $SG_QUOTE_ARRAY, $SG_HIDDEN_FIELDS;global $SG_QUOTE_ARRAY, $SG_HIDDEN_FIELDS;
//$quote_array = load_quote_array();//$quote_array = load_quote_array();
generate_form_tag($SG_QUOTE_ARRAY);generate_form_tag($SG_QUOTE_ARRAY);
echo("<table>\n");echo("<table>\n");
generate_input_tag($SG_QUOTE_ARRAY, "text", 10);generate_input_tag($SG_QUOTE_ARRAY, "text", 10);
generate_input_tag($SG_QUOTE_ARRAY, "password", 10);generate_input_tag($SG_QUOTE_ARRAY, "password", 10);
$hidden_fields = mt_rand(0, $SG_HIDDEN_FIELDS);$hidden_fields = mt_rand(0, $SG_HIDDEN_FIELDS);
for($i = 0; $i < $hidden_fields; $i++) {for($i = 0; $i < $hidden_fields; $i++) {
generate_input_tag($SG_QUOTE_ARRAY, "hidden", 0);generate_input_tag($SG_QUOTE_ARRAY, "hidden", 0);
}}
generate_input_tag($SG_QUOTE_ARRAY, "submit", 0);generate_input_tag($SG_QUOTE_ARRAY, "submit", 0);
echo("</table>\n");echo("</table>\n");
generate_form_end();generate_form_end();
}}
DOG_CrawlerDOG_Crawler
Techniques against anti-Techniques against anti-automatization automatization
Test of Method HEADTest of Method HEAD Analyzes of ContentAnalyzes of Content Signature of ReplySignature of Reply Detection of Honeypots Links and FormDetection of Honeypots Links and Form Heuristic and RandomHeuristic and Random Distributed automatizationDistributed automatization
Test of Method HEADTest of Method HEAD
$ echo -e "HEAD / HTTP/1.0\n\n" | nc 192.168.1.1 80HTTP/1.1 406 Not AcceptableDate: Fri, 16 Sep 2005 05:27:00 GMTServer: Apache/1.3.31 (Unix) PHP/4.3.7Connection: closeContent-Type: text/html; charset=iso-8859-1
/HTTP\/*.* (200)/ig
If not to find the code of reply "200" the defense was detectedIf not to find the code of reply "200" the defense was detected
Analyzes of ContentAnalyzes of Content
$ echo -e "GET /index.gif HTTP/1.0\n\n" | nc 192.168.1.1 80HTTP/1.1 200 OKDate: Fri, 16 Sep 2005 12:00:56 GMTServer: Apache/1.3.31 (Unix) PHP/4.3.7Last-Modified: Wed, 14 Sep 2005 06:31:42 GMTETag: "47efb-732-4327c3ce"Accept-Ranges: bytesContent-Length: 1842Connection: closeContent-Type: text/htmlX-Pad: avoid browser bug<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 3.2 Final//EN"><html><head>…
– /=*([\w|\/|\.|\:]+.html)/ig– /=\"([\w|\/|\-]+.asp|.jsp|.php)/ig– /=\"([\w|\/|\-]+.gif)/ig– /=\"([\w|\/|\-]+.jpg)/ig– /=\"([\w|\/|\-]+.png)/ig– /=\"([\w|\/|\-]+.gif|.jpg|.png)/ig– /Content-Type: *([a-z&\/&\-]+)/i– /href=\"([\w|\/|\.|\:]+)/ig– /MIME-Version/– //(\%3C|<|\<)META*.content=*([a-z&\/&\-]+)/ig
Regular ExpressionsRegular Expressions
Analyzes of ContentAnalyzes of Content
Signature of ReplySignature of Reply
Detection of Honeypots Detection of Honeypots Links Links
<--! HREF="../honeypot.html"> --> <FONT COLOR="black"><HREF="../honeypot.html">escondido</A></FONT>
/(\%3C|<|\<)!--.*href=([\w|\/|\.|\:]+)*.-- (\%3C|>|\>)/ig
Honeypot linksHoneypot links
Link in the commentary detects HoneypotLink in the commentary detects Honeypot
HeuristicHeuristic
Heuristic MyopeHeuristic Myope
Algoritmo Míope(n, c, S, F) [Max {c(S) / S F}] Início Ordenar os elementos de E de forma que: C(s1) ≥ c(s2) ≥ ... ≥ c(sn) > 0; S := Ø; Para i = 1 até n fazer Se [S {si}] F então S := S {si}; Escrever {S, c(S) = ∑ c(s)}; Fim
RandomRandom
PERMUTE-BY-SORTING(A) n comprimento[A] for i 1 to n do P[i] = RANDOM(1, n3) ordenar A, usando P como chaves de ordenação return A
Xn+1 = KXn(módulo M)sendo- n = 1,2,3,...- x0 é um número aleatório inicial (semente), onde 0 < x0 < M;- K é número inteiro, tal que 0 < K < M- M = 10b + 1, onde b é quantidade de algarismos;
Random permutation of ArrangementsRandom permutation of Arrangements
Congruencial method MultiplicationCongruencial method Multiplication
Distributed automatizationDistributed automatization
WebServer DB
DB
Web app
Web app
Web app
Web app
1
2
3
4
0
[1] Gunter Ollmann – Second-order Code Injection Attacks http://www.ngssoftware.com/papers/StoppingAutomatedAttackTools.pdf[2] Saumil Shah - Defeating Automated Web Assessment Tools http://www.blackhat.com/presentations/bh-europe-05/BH_EU_05-Shah.pdf[3] SensePost - Revolutions in Web Server/Application Assessments http://www.blackhat.com/presentations/bh-europe-05/bh-eu-05-sensepost.pdf[4] http://www.owasp.org
SitesSites
DEMODEMO
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