CVE-2001-0367 in ICQ
Summary
by MITRE
Mirabilis ICQ WebFront Plug-in ICQ2000b Build 3278 allows a remote attacker to create a denial of service via HTTP URL requests containing a large number of % characters.
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Analysis
by VulDB Data Team • 05/31/2019
The vulnerability identified as CVE-2001-0367 affects the Mirabilis ICQ WebFront Plug-in version ICQ2000b Build 3278, representing a classic denial of service weakness that exploits improper input handling in web-based applications. This issue manifests when remote attackers submit HTTP URL requests containing an excessive number of percent encoding characters, specifically % characters, which triggers unexpected behavior in the plugin's processing logic. The flaw resides in the plugin's inability to properly sanitize or limit the number of percent characters in URL parameters, creating a condition where the system becomes overwhelmed during request parsing and validation processes.
The technical implementation of this vulnerability stems from inadequate input validation mechanisms within the ICQ WebFront Plug-in's URL processing module. When the plugin encounters URLs with an excessive concentration of % characters, it fails to implement reasonable limits or proper parsing logic for percent-encoding sequences. This weakness falls under CWE-129, Input Validation, and specifically relates to CWE-770, Allocation of Resources Without Limits or Throttling, as the system does not properly throttle or limit the number of percent characters that can be processed. The plugin's URL parser likely attempts to interpret each % character as the beginning of a URL-encoded sequence, leading to exponential processing time or memory allocation issues as the system tries to decode what appears to be an increasingly malformed URL structure.
From an operational perspective, this vulnerability presents a significant risk to systems hosting the affected ICQ WebFront Plug-in, as it enables remote attackers to disrupt service availability without requiring authentication or specialized privileges. The denial of service impact occurs when legitimate users are unable to access the web-based ICQ functionality due to the plugin's failure to process requests properly, potentially affecting communication services for users relying on ICQ integration. Attackers can exploit this weakness by crafting malicious URLs with thousands or tens of thousands of % characters, causing the web server or application to consume excessive CPU resources or memory, ultimately leading to system unresponsiveness or complete service termination. The vulnerability operates at the application layer, making it particularly dangerous as it can be exploited through standard web browsers or automated tools without requiring direct system access.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and rate limiting mechanisms at the web server level. Organizations should deploy URL filtering rules that limit the number of consecutive percent characters in URL requests, effectively preventing the exploitation of this specific weakness. The recommended approach involves configuring web application firewalls or server configurations to reject requests containing excessive percent encoding sequences, typically setting thresholds below the problematic range. Additionally, system administrators should consider upgrading to newer versions of the ICQ WebFront Plug-in that address this vulnerability through improved input sanitization and resource allocation controls. The remediation process should also include implementing monitoring and alerting for unusual patterns of URL requests that might indicate exploitation attempts, aligning with ATT&CK technique T1499.004 for Network Denial of Service. Security teams should also ensure that the affected plugin is either updated to a patched version or removed from production environments until proper remediation can be implemented, as this vulnerability represents a critical weakness that can be exploited without advanced technical skills or privileged access.