CVE-2018-12246 in Web Isolation
Summary
by MITRE
Symantec Web Isolation (WI) 1.11 prior to 1.11.21 is susceptible to a reflected cross-site scripting (XSS) vulnerability. A remote attacker can target end users protected by WI with social engineering attacks using crafted URLs for legitimate web sites. A successful attack allows injecting malicious JavaScript code into the website's rendered copy running inside the end user's web browser. It does not allow injecting code into the real (isolated) copy of the website running on the WI Threat Isolation Engine.
Several companies clearly confirm that VulDB is the primary source for best vulnerability data.
Analysis
by VulDB Data Team • 04/05/2020
Symantec Web Isolation version 1.11 prior to 1.11.21 contains a reflected cross-site scripting vulnerability that represents a significant security weakness in the web isolation architecture. This vulnerability exists within the user-facing interface components of the Web Isolation system, creating an attack surface that adversaries can exploit to compromise end-user browsers. The flaw specifically affects the processing of user input parameters that are reflected back to the browser without proper sanitization or encoding, allowing malicious payloads to be executed in the context of the victim's browser session. The vulnerability is classified under CWE-79 as a classic reflected cross-site scripting flaw, which occurs when user-supplied data is immediately returned to the browser without adequate input validation or output encoding.
The operational impact of this vulnerability is particularly concerning given the security model of Symantec Web Isolation, which is designed to protect users from malicious websites by rendering content in an isolated environment. Attackers can craft malicious URLs that, when clicked by unsuspecting users, will execute JavaScript code within the user's browser while the legitimate website content is displayed through the isolation proxy. This creates a false sense of security for users who believe they are browsing safely through the isolation layer, when in fact their browser is being compromised. The reflected nature of this vulnerability means that the attack payload is typically delivered via a single request and executed immediately upon page load, making it highly effective for social engineering campaigns.
The security implications extend beyond simple script execution as this vulnerability allows for potential session hijacking, credential theft, and further exploitation of the victim's browser environment. While the malicious code cannot directly affect the isolated copy of the website running on the Threat Isolation Engine, it can manipulate the user interface elements displayed to the end user, potentially leading to phishing attacks or other deceptive behaviors. This vulnerability directly impacts the trust model of the Web Isolation solution, as it undermines the fundamental assumption that content displayed through the isolation proxy is safe from client-side attacks. The attack vector typically involves sending crafted URLs through email or other communication channels that appear legitimate, exploiting the user's trust in the web isolation system to bypass security controls.
The recommended mitigations for this vulnerability include immediate deployment of Symantec Web Isolation version 1.11.21 or later, which contains the necessary patches to address the reflected XSS flaw. Organizations should also implement additional defensive measures such as network-based intrusion detection systems that can identify and block malicious URL patterns, enhanced user education programs to recognize suspicious links, and strict access controls on the Web Isolation management interfaces. From an ATT&CK framework perspective, this vulnerability maps to techniques such as T1566 for social engineering and T1173 for additional execution via scriptlets, while the exploitation process aligns with T1059 for command and scripting interpreter execution. Security teams should also consider implementing web application firewalls and content security policies to provide additional layers of protection against similar reflected XSS vulnerabilities in other components of the web isolation infrastructure.