CVE-2000-0203 in OfficeScan
Summary
by MITRE
The Trend Micro OfficeScan client tmlisten.exe allows remote attackers to cause a denial of service via malformed data to port 12345.
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Analysis
by VulDB Data Team • 04/20/2026
The vulnerability identified as CVE-2000-0203 resides within the Trend Micro OfficeScan client software, specifically in the tmlisten.exe component that operates on TCP port 12345. This flaw represents a classic denial of service vulnerability that exploits improper input validation mechanisms within the listening service. The vulnerability stems from the application's failure to properly handle malformed data packets sent to the designated port, creating a condition where legitimate service operations can be disrupted through carefully crafted malicious inputs.
The technical nature of this vulnerability aligns with CWE-121, which categorizes buffer overflow conditions that occur when insufficient bounds checking is performed on data inputs. The tmlisten.exe service appears to lack adequate data sanitization routines that would normally validate incoming data formats before processing them. When malformed data reaches port 12345, the service either crashes or becomes unresponsive, effectively rendering the OfficeScan client functionality unavailable to legitimate users. This behavior constitutes a remote denial of service attack since attackers can exploit the vulnerability from any network location without requiring local access or authentication credentials.
From an operational impact perspective, this vulnerability significantly compromises the availability of security services provided by Trend Micro OfficeScan clients. Organizations relying on this software for endpoint protection face potential security gaps when the client service becomes unavailable, as the system cannot properly monitor or respond to threats. The attack vector is particularly concerning because it requires no privileged access and can be executed from remote locations, making it an attractive target for malicious actors seeking to disrupt business operations or create cover for other attacks. The vulnerability also demonstrates the importance of network segmentation and proper firewall rules to limit exposure of unnecessary services.
Mitigation strategies for this vulnerability should include immediate patching of affected OfficeScan client versions through Trend Micro's official update channels. Network administrators should implement firewall rules to block external access to port 12345, as this port appears to be unnecessary for normal client operations. The principle of least privilege should be applied by ensuring that only authorized systems can access this service port. Additionally, monitoring systems should be configured to detect unusual traffic patterns or service disruptions on port 12345, which could indicate exploitation attempts. This vulnerability also highlights the importance of following ATT&CK framework tactics, particularly T1499 which covers network denial of service attacks, and emphasizes the need for comprehensive endpoint protection strategies that include regular security updates and proper network segmentation practices.