CVE-2015-3000 in Help Desk
Summary
by MITRE
SysAid Help Desk before 15.2 allows remote attackers to cause a denial of service (CPU and memory consumption) via a large number of nested entity references in an XML document to (1) /agententry, (2) /rdsmonitoringresponse, or (3) /androidactions, aka an XML Entity Expansion (XEE) attack.
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Analysis
by VulDB Data Team • 08/10/2024
The vulnerability identified as CVE-2015-3000 represents a critical XML External Entity expansion flaw in SysAid Help Desk software versions prior to 15.2. This vulnerability resides in the application's processing of XML documents through three specific endpoints: /agententry, /rdsmonitoringresponse, and /androidactions. The flaw enables remote attackers to exploit the system's XML parser by submitting maliciously constructed XML documents containing a large number of nested entity references. This particular vulnerability maps directly to CWE-611, which specifically addresses XML External Entity (XXE) processing vulnerabilities, and aligns with ATT&CK technique T1213.002 for data from other sources. The attack vector is particularly concerning as it requires no authentication and can be executed from any remote location, making it highly accessible to threat actors.
The technical implementation of this vulnerability exploits the fundamental way XML parsers handle entity references. When the SysAid Help Desk application processes XML documents through the affected endpoints, it recursively expands entity references without proper input validation or resource limits. This recursive expansion creates a massive payload that consumes excessive CPU cycles and memory resources. The nested entity references cause the parser to continuously expand and process entities, leading to exponential resource consumption that can quickly exhaust system resources. The vulnerability specifically targets the XML parsing libraries used by the application, leveraging the parser's inherent behavior to process entity references without adequate safeguards against maliciously crafted inputs.
The operational impact of this vulnerability extends beyond simple denial of service, as it can effectively render the help desk system completely unavailable to legitimate users. Attackers can consume system resources at an exponential rate, causing the application servers to become unresponsive or crash entirely. This leads to significant business disruption, as help desk services become inaccessible to both end users and support staff. The resource exhaustion occurs rapidly, often within minutes of the attack initiation, making it particularly damaging for organizations that rely heavily on their help desk systems for daily operations. The vulnerability affects not only the availability of the specific endpoints but can also impact the overall system stability, potentially causing cascading failures across related services.
Organizations should immediately implement several mitigation strategies to address this vulnerability. The primary defense involves updating to SysAid Help Desk version 15.2 or later, which includes proper input validation and resource limits for XML parsing. Additionally, network-level firewalls should be configured to restrict access to the affected endpoints, particularly when external access is not required. Implementing XML parser configuration changes to disable external entity resolution and DTD processing provides additional layers of protection. Security monitoring should be enhanced to detect unusual patterns of XML processing activity that might indicate exploitation attempts. The vulnerability demonstrates the importance of input validation and proper resource management in XML processing applications, aligning with security best practices outlined in OWASP Top Ten and NIST guidelines for secure coding practices. Organizations should also consider implementing intrusion detection systems that can identify and alert on suspicious XML processing patterns that may indicate XXE attacks.