CVE-2011-3140 in G400 Ips-g400-ib-1 Appliance
Summary
by MITRE
IBM Web Application Firewall, as used on the G400 IPS-G400-IB-1 and GX4004 IPS-GX4004-IB-2 appliances with update 31.030, does not properly handle query strings with multiple instances of the same parameter, which allows remote attackers to bypass intended intrusion prevention by dividing a dangerous parameter value into substrings, as demonstrated by a SQL statement that is split across multiple iid parameters and then sent to a .aspx file on an IIS web server.
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Analysis
by VulDB Data Team • 01/24/2018
The vulnerability identified as CVE-2011-3140 affects IBM Web Application Firewall appliances including the G400 IPS-G400-IB-1 and GX4004 IPS-GX4004-IB-2 models when running update 31.030. This security flaw represents a critical weakness in the intrusion prevention system's parameter handling mechanism, specifically concerning query string parsing and validation. The vulnerability stems from the appliance's inability to properly process query strings containing multiple occurrences of identical parameter names, creating a significant bypass opportunity for malicious actors seeking to circumvent security controls.
The technical flaw manifests when the web application firewall processes HTTP requests containing query strings with duplicate parameter names. In normal operation, a web application firewall should aggregate or properly validate multiple instances of the same parameter to prevent security bypasses. However, the IBM appliance fails to correctly handle this scenario, allowing attackers to fragment malicious payloads across multiple parameter instances. This design deficiency enables attackers to split dangerous parameter values into smaller substrings that individually appear benign but collectively form a complete malicious request when processed by the target web server.
The operational impact of this vulnerability is severe as it allows remote attackers to bypass the intended security controls of the intrusion prevention system. Attackers can exploit this weakness by crafting HTTP requests where a single malicious parameter value is distributed across multiple instances of the same parameter name. For example, a SQL injection payload could be split across multiple iid parameters, with each parameter containing a portion of the complete SQL statement. When these requests reach the target IIS web server hosting .aspx files, the fragmented malicious input is processed as a single complete attack vector, potentially enabling unauthorized database access, data manipulation, or system compromise.
This vulnerability directly relates to CWE-444, which describes improper handling of HTTP requests with multiple parameters, and aligns with ATT&CK technique T1071.004 for application layer protocol manipulation. The flaw represents a classic case of input validation bypass where the security appliance's processing logic fails to account for the possibility of malicious data fragmentation. The attack vector demonstrates how a seemingly minor parsing issue in the firewall's query string handling can create a significant security gap that undermines the entire purpose of the intrusion prevention system. Organizations deploying these appliances face a substantial risk of bypassing security controls, particularly when dealing with applications that are vulnerable to SQL injection or other parameter-based attacks.
The mitigation strategy should focus on applying the vendor's official security patches or updates that address the query string handling behavior. Network administrators must also consider implementing additional monitoring and logging mechanisms to detect unusual parameter patterns in HTTP requests. Organizations should review their existing security policies to ensure proper input validation is implemented at multiple layers of their infrastructure, including both the web application firewall and the target web servers themselves. Regular security assessments and penetration testing should be conducted to identify similar parameter handling vulnerabilities in other network security devices and web applications. The vulnerability highlights the importance of comprehensive security testing that includes edge cases such as parameter duplication and fragmentation scenarios.