CVE-2020-4589 in WebSphere Application Server
Summary
by MITRE
IBM WebSphere Application Server 7.0, 8.0, 8.5, and 9.0 could allow a remote attacker to execute arbitrary code on the system with a specially-crafted sequence of serialized objects from untrusted sources. The vulnerability only occurs if an undocumented customization has been applied by an administrator. IBM X-Force ID: 184585.
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Analysis
by VulDB Data Team • 11/09/2020
IBM WebSphere Application Server versions 7.0, 8.0, 8.5, and 9.0 contain a critical remote code execution vulnerability that stems from improper deserialization of untrusted data within the application server's object serialization framework. This vulnerability represents a classic deserialization flaw that allows attackers to craft malicious serialized object sequences that, when processed by the server, trigger arbitrary code execution on the underlying system. The flaw specifically manifests when administrators have implemented an undocumented customization that enables certain deserialization behaviors, making the vulnerability exploitable in targeted environments where such modifications have been applied.
The technical nature of this vulnerability aligns with CWE-502, which describes deserialization of untrusted data as a critical security weakness. Attackers can leverage this vulnerability by sending specially crafted serialized objects to the WebSphere server through network connections that accept object input. When the server processes these objects during deserialization, it executes malicious code with the privileges of the application server process, potentially allowing full system compromise. The vulnerability's exploitation requires specific conditions since it only activates when administrators have applied undocumented customizations that modify the default deserialization behavior, making the attack surface more limited but no less dangerous when present.
The operational impact of CVE-2020-4589 is severe as it provides attackers with a direct path to execute arbitrary code on affected systems without requiring authentication or specific user interaction. This capability enables attackers to establish persistent access, escalate privileges, and potentially move laterally within the network. The vulnerability affects organizations running IBM WebSphere Application Server in production environments, where the server may be directly exposed to untrusted networks or where internal applications communicate with external services that could be compromised. The remote exploitation capability means that attackers can target these systems from anywhere on the internet, making the vulnerability particularly dangerous for organizations with exposed server instances.
Organizations should implement immediate mitigations including applying the relevant IBM security patches that address the deserialization vulnerability in WebSphere Application Server. Additionally, administrators should review and remove any undocumented customizations that enable the vulnerable deserialization behavior, as these modifications create the necessary conditions for exploitation. Network segmentation and firewall rules should be implemented to restrict access to WebSphere server instances from untrusted networks, while monitoring should be enhanced to detect unusual object deserialization patterns. The vulnerability also aligns with ATT&CK technique T1059.007 for remote code execution and T1210 for exploitation of remote services, making it a significant concern for security teams implementing threat detection and response capabilities. Regular security assessments and vulnerability scanning should be conducted to ensure that no unauthorized modifications have been applied to the application server configuration.