CVE-2007-3716 in JDK
Summary
by MITRE
The Java XML Digital Signature implementation in Sun JDK and JRE 6 before Update 2 does not properly process XSLT stylesheets in XSLT transforms in XML signatures, which allows context-dependent attackers to execute arbitrary code via a crafted stylesheet, a related issue to CVE-2007-3715.
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Analysis
by VulDB Data Team • 07/22/2019
The vulnerability described in CVE-2007-3716 represents a critical security flaw in the Java XML Digital Signature implementation within Sun JDK and JRE 6 before Update 2. This issue specifically targets the processing of XSLT stylesheets within XSLT transforms that are part of XML signatures, creating a significant attack surface that can be exploited by context-dependent malicious actors. The flaw stems from inadequate validation and processing of XSLT transforms, which are commonly used to transform XML data during signature operations. When an XML signature contains a malicious XSLT stylesheet, the vulnerable Java implementation fails to properly sanitize or restrict the execution context, potentially allowing arbitrary code execution. This vulnerability is particularly concerning because it operates within the core security infrastructure of Java applications, where XML signatures are frequently used for digital authentication and data integrity verification. The issue is classified under CWE-22 as a "Path Traversal" vulnerability, specifically involving improper handling of external references in XML processing, and aligns with ATT&CK technique T1059.007 for "Command and Scripting Interpreter: XSLT Stylesheet" which demonstrates how attackers can leverage XSLT processing to execute malicious payloads.
The technical implementation flaw manifests when the Java XML Digital Signature API processes XSLT transforms that reference external resources or contain malicious transformation logic. The vulnerability occurs during the signature validation phase where the system attempts to process XSLT transformations that are part of the XML signature structure. When attackers craft malicious XSLT stylesheets that include references to external resources or contain embedded executable code, the vulnerable implementation fails to properly isolate or restrict the execution environment. This allows attackers to potentially execute arbitrary code on systems running the affected Java versions. The flaw is particularly dangerous because XSLT transformations are designed to be flexible and powerful, enabling complex data manipulations, but this same flexibility creates opportunities for exploitation when proper input validation and sandboxing mechanisms are absent. The vulnerability directly impacts the integrity of XML signature validation processes, potentially allowing attackers to bypass security controls that rely on XML signatures for authentication and authorization purposes.
The operational impact of CVE-2007-3716 extends beyond simple code execution, affecting the fundamental security assurances that XML signatures are meant to provide. Systems running vulnerable Java implementations become susceptible to attacks that can compromise the integrity of digital signatures, potentially allowing attackers to forge signatures or manipulate signed data. This vulnerability particularly affects enterprise applications that rely heavily on XML signatures for secure communications, document signing, and authentication processes. The context-dependent nature of the attack means that exploitation requires specific conditions where the vulnerable system processes malicious XML signatures containing crafted XSLT transforms. Organizations using Java-based web services, enterprise applications, and security infrastructure that handles XML signatures are at risk, as attackers could leverage this vulnerability to gain unauthorized access to sensitive systems or data. The attack vector typically involves delivering a specially crafted XML document containing a malicious XSLT transform that gets processed during signature validation, making this a particularly insidious threat to systems that process untrusted XML data.
Mitigation strategies for CVE-2007-3716 primarily focus on immediate patching and implementation of additional security controls. The most effective solution is to apply the security update released by Sun Microsystems for JDK and JRE 6 Update 2 or later versions, which addresses the improper XSLT stylesheet processing behavior. Organizations should also implement strict XML processing controls, including disabling external entity references and restricting access to external resources during XSLT processing. Network segmentation and input validation measures can help reduce the attack surface, while monitoring for suspicious XML processing activities can aid in detecting potential exploitation attempts. Security teams should also consider implementing application-level controls that restrict the use of XSLT transforms in XML signature processing where possible, and establish robust testing procedures for XML signature validation components. The vulnerability highlights the importance of proper sandboxing and isolation mechanisms in XML processing libraries, and organizations should review their XML processing configurations to ensure that external references are properly restricted and that transformation processes are adequately secured against malicious inputs. Additionally, implementing security awareness training for developers about the risks of XSLT processing in XML signatures can help prevent future vulnerabilities in custom implementations.