CVE-2018-11694 in LibSaas
Summary
by MITRE
An issue was discovered in LibSaas through 3.5.4. A NULL pointer dereference was found in the function Sass::Functions::selector_append which could be leveraged by an attacker to cause a denial of service (application crash) or possibly have unspecified other impact.
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Analysis
by VulDB Data Team • 03/21/2023
The vulnerability identified as CVE-2018-11694 represents a critical NULL pointer dereference flaw within the LibSass library version 3.5.4 and earlier. This issue specifically manifests within the Sass::Functions::selector_append function, which is part of the Sass stylesheet language implementation used for generating CSS from Sass markup. The flaw occurs when the function processes certain input parameters that result in a null pointer being dereferenced during execution, creating a condition that can lead to application instability.
This vulnerability falls under the CWE-476 category of NULL Pointer Dereference, which is a common software security weakness that occurs when an application attempts to access a memory location through a pointer that has been set to null. The attack vector for CVE-2018-11694 involves malicious input being processed through the Sass compilation pipeline, where the selector_append function fails to properly validate input parameters before attempting to dereference pointers. The specific nature of this flaw means that an attacker could craft specially formatted Sass code that when compiled through LibSass would trigger the NULL pointer dereference, leading to a program crash or potential system instability.
The operational impact of this vulnerability extends beyond simple denial of service, as it could potentially be exploited to cause more severe consequences depending on the environment where LibSass is deployed. When an application using LibSass encounters the malformed input that triggers this vulnerability, the application process will terminate unexpectedly, causing service disruption for users. In web applications or continuous integration systems that rely on LibSass for dynamic CSS generation, this could result in complete service outages or system unavailability. The vulnerability is particularly concerning because it affects the core compilation functionality of the Sass processing engine, making it a potential target for attackers seeking to disrupt web services or build systems that depend on this library.
Organizations using LibSass in their development workflows or web applications should prioritize immediate remediation through updating to version 3.5.5 or later, which contains the necessary patches to address the NULL pointer dereference issue. The fix implemented in the updated versions involves proper input validation and null pointer checks within the selector_append function to prevent the dereference condition from occurring. Additionally, implementing proper input sanitization and validation at the application level can provide additional defense in depth against potential exploitation attempts. Security teams should also consider monitoring for any attempts to exploit this vulnerability in their environments, particularly in systems that process untrusted Sass input or user-generated content that could be used to craft the malicious payloads designed to trigger the NULL pointer dereference. The ATT&CK framework categorizes this type of vulnerability under software exploitation techniques, specifically targeting application stability and availability through memory corruption flaws that can be leveraged for denial of service attacks.