CVE-1999-0107 in HTTP Server
Summary
by MITRE
buffer overflow in apache 1.2.5 and earlier allows a remote attacker to cause a denial of service with a large number of get requests containing a large number of / characters.
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Analysis
by VulDB Data Team • 11/28/2024
The vulnerability identified as CVE-1999-0107 represents a critical buffer overflow flaw affecting Apache HTTP Server versions 1.2.5 and earlier. This security weakness resides in the server's handling of HTTP GET requests, specifically when processing URLs containing an excessive number of forward slash characters. The flaw demonstrates a classic buffer overflow condition where insufficient input validation allows malicious actors to overflow memory buffers allocated for processing request paths. The vulnerability operates at the application layer and requires no authentication to exploit, making it particularly dangerous for publicly accessible web servers. The attack vector leverages the server's inability to properly sanitize and limit the length of URL path components, creating a scenario where malformed requests can trigger memory corruption.
The technical implementation of this vulnerability stems from the Apache server's internal parsing mechanism for URI paths. When processing GET requests, the server allocates fixed-size buffers to store and process the requested resource paths. An attacker can craft malicious requests containing an excessive number of consecutive forward slashes that exceed the allocated buffer boundaries. This overflow condition typically occurs during path normalization or parsing operations where the server attempts to resolve the requested resource location. The buffer overflow can manifest in various ways including stack corruption, heap corruption, or memory overwrite conditions that ultimately result in the server process crashing or becoming unresponsive. The flaw is particularly insidious because it can be triggered through simple HTTP GET requests without requiring any special privileges or authentication credentials.
The operational impact of CVE-1999-0107 extends beyond simple service disruption to encompass potential system instability and denial of service conditions that can affect entire web server operations. When exploited successfully, the buffer overflow causes the Apache process to terminate unexpectedly, resulting in immediate service unavailability for all users accessing the affected server. This denial of service condition can persist until the server administrator manually restarts the Apache service or the system automatically recovers from the crash. The vulnerability affects organizations relying on older Apache versions, creating significant operational risks for businesses dependent on web services. Network administrators may experience extended downtime while investigating and implementing fixes, potentially affecting revenue generation and customer satisfaction. The flaw also increases the attack surface for more sophisticated attacks that might follow the initial denial of service attempt.
Mitigation strategies for CVE-1999-0107 primarily focus on immediate version upgrades to Apache 1.3.0 or later, which contain fixed implementations of URI parsing and buffer management. System administrators should prioritize updating their Apache installations to versions that properly validate input length and implement appropriate bounds checking mechanisms. Additionally, implementing rate limiting mechanisms and request filtering can provide temporary protection while upgrades are being deployed. Network-level protections such as firewalls and intrusion detection systems can be configured to monitor for unusual patterns of GET requests containing excessive forward slashes. The implementation of input validation rules that limit the maximum number of path components or forward slashes in URLs provides an additional layer of defense. Organizations should also consider implementing web application firewalls that can detect and block malformed requests before they reach the Apache server. Security monitoring should include detection of unusual process termination patterns and system crash events that may indicate exploitation attempts. This vulnerability aligns with CWE-121 and CWE-122 categories related to buffer overflow conditions and improper input validation, while the attack methodology corresponds to ATT&CK technique T1499 for network denial of service attacks.