Dell AppSync, version(s) 4.6.0.0, contains an Improper Restriction of XML External Entity Reference vulnerability. A low privileged attacker with local access could potentially exploit this vulnerability, leading to Information disclosure and Information tampering.
Dell AppSync (versions 4.6.0.0) is vulnerable to an XML External Entity (XXE) injection attack, allowing a local, low-privileged attacker to potentially achieve information disclosure and data tampering. Exploitation leverages improper handling of XML input, enabling the attacker to read sensitive files or modify application data. This vulnerability poses a significant risk to data integrity and confidentiality within the AppSync environment.
Step 1: Payload Creation: The attacker crafts a malicious XML payload. This payload includes an XML External Entity (XXE) reference, pointing to a local file (e.g., /etc/passwd) or an internal network resource. The payload is designed to be submitted to AppSync through a vulnerable input point.
Step 2: Payload Delivery: The attacker submits the crafted XML payload to the Dell AppSync application. This could be through a web interface, API call, or other input mechanisms that accept XML data.
Step 3: XML Parsing: AppSync's XML parser receives and processes the malicious XML payload.
Step 4: Entity Resolution: The vulnerable XML parser, due to the lack of proper configuration, attempts to resolve the external entity reference defined in the payload.
Step 5: Information Disclosure/Tampering: The parser retrieves the content of the specified local file (e.g., /etc/passwd) or interacts with the internal network resource. The content is then either returned to the attacker (information disclosure) or used to modify application data or system files (data tampering).
The vulnerability stems from the lack of proper input validation and sanitization of XML data processed by Dell AppSync. Specifically, the application fails to disable or restrict the processing of external entities within XML documents. This allows an attacker to craft a malicious XML payload containing references to external resources, such as local files or internal network services. When AppSync parses this malicious XML, it attempts to resolve these external entity references, leading to information disclosure (e.g., reading sensitive files like configuration files, credentials, or other internal documents) or data tampering (e.g., writing arbitrary data to the file system or modifying application settings). The root cause is the absence of a secure XML parser configuration, which should include disabling external entity resolution or implementing a whitelist of allowed entities.