CVE-2011-4041 in WebAccess
Summary
by MITRE
webvrpcs.exe in Advantech/BroadWin WebAccess allows remote attackers to execute arbitrary code or obtain a security-code value via a long string in an RPC request to TCP port 4592.
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Analysis
by VulDB Data Team • 10/22/2024
The vulnerability identified as CVE-2011-4041 affects the webvrpcs.exe component within Advantech/BroadWin WebAccess software, presenting a critical remote code execution risk. This flaw exists in the handling of RPC (Remote Procedure Call) requests processed by the webvrpcs.exe service, which listens on TCP port 4592. The vulnerability stems from insufficient input validation and buffer management within the RPC processing logic, creating an exploitable condition that allows remote attackers to craft malicious requests containing excessively long strings. The affected service fails to properly validate the length of incoming RPC parameters, leading to potential buffer overflow conditions that can be leveraged for arbitrary code execution.
The technical implementation of this vulnerability involves the manipulation of RPC request parameters through TCP port 4592, where the webvrpcs.exe process receives and processes incoming requests. When an attacker sends a malformed RPC request containing an unusually long string, the service's inadequate input validation causes the application to attempt to process data beyond its allocated memory boundaries. This buffer overflow condition can be exploited to overwrite critical memory segments, including return addresses and function pointers, allowing an attacker to redirect execution flow and inject malicious code. The vulnerability is particularly concerning as it does not require authentication, making it accessible to any remote attacker who can reach the target system.
The operational impact of CVE-2011-4041 extends beyond simple code execution, as it also enables attackers to obtain security-code values that may be used for further exploitation or privilege escalation. This dual capability significantly increases the risk to affected systems, as the vulnerability can be leveraged for both initial compromise and subsequent lateral movement within network environments. The security-code extraction aspect of this vulnerability aligns with attack patterns documented in the MITRE ATT&CK framework under the 'Credential Access' and 'Execution' tactics, where attackers seek to obtain sensitive information and establish persistent access. Organizations running Advantech/BroadWin WebAccess software are particularly vulnerable, as the affected service often runs with elevated privileges, potentially allowing attackers to gain system-level access.
Mitigation strategies for this vulnerability should focus on immediate patching of the affected WebAccess software to address the buffer overflow conditions in the webvrpcs.exe component. Organizations should also implement network segmentation to restrict access to TCP port 4592, particularly through firewall rules that limit access to trusted IP addresses only. Additionally, monitoring for unusual RPC request patterns and implementing intrusion detection systems can help identify potential exploitation attempts. The vulnerability demonstrates characteristics consistent with CWE-121, Buffer Overflow in Stack, and CWE-78, Improper Neutralization of Special Elements used in OS Command, indicating the need for comprehensive input validation and memory management practices. Security teams should also consider disabling the RPC service entirely if it is not required for business operations, as this provides the most effective defense against exploitation of this and similar vulnerabilities.