CVE-2007-5984 in AutoIndex PHP Script
Summary
by MITRE
classes/Url.php in Justin Hagstrom AutoIndex PHP Script before 2.2.4 allows remote attackers to cause a denial of service (CPU and memory consumption) via a %00 sequence in the dir parameter to index.php, which triggers an erroneous "recursive calculation."
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Analysis
by VulDB Data Team • 04/05/2025
The vulnerability described in CVE-2007-5984 affects the Justin Hagstrom AutoIndex PHP Script version 2.2.3 and earlier, representing a denial of service flaw that can be exploited through careful manipulation of input parameters. This vulnerability specifically targets the classes/Url.php component within the script's architecture, where improper handling of directory traversal parameters creates a condition that leads to excessive resource consumption. The attack vector involves sending a maliciously crafted request containing a null byte sequence %00 in the dir parameter of the index.php script, which triggers an abnormal recursive calculation process.
The technical root cause of this vulnerability lies in the inadequate input validation and sanitization mechanisms within the AutoIndex script's URL processing functionality. When the application encounters the %00 sequence in the dir parameter, it fails to properly terminate string processing or validate the input boundaries, leading to a recursive calculation loop that consumes excessive CPU cycles and memory resources. This behavior constitutes a classic example of a resource exhaustion attack pattern that can be classified under CWE-400, which deals with uncontrolled resource consumption. The vulnerability demonstrates poor input handling practices that allow attackers to manipulate the application's control flow and trigger unintended computational overhead.
The operational impact of this vulnerability extends beyond simple service disruption to potentially compromise system availability and stability. An attacker can exploit this flaw to consume significant system resources, potentially leading to complete system unresponsiveness or crash of the web server hosting the vulnerable AutoIndex script. The recursive calculation process continues until system resources are depleted, making this a particularly effective denial of service mechanism. This type of attack can be particularly damaging in shared hosting environments where resource exhaustion on one application can impact other services running on the same server infrastructure.
Mitigation strategies for this vulnerability should focus on implementing proper input validation and sanitization measures within the affected PHP script. The most effective approach involves modifying the Url.php component to properly handle null byte sequences and terminate string processing at appropriate boundaries. Implementing strict input validation that rejects or sanitizes null byte characters in directory parameters would prevent the recursive calculation from being triggered. Additionally, system administrators should ensure that the AutoIndex script is updated to version 2.2.4 or later, where this vulnerability has been addressed. Network-level protections such as web application firewalls can also provide additional defense in depth by filtering out suspicious input patterns containing null byte sequences. The vulnerability aligns with ATT&CK technique T1499.004, which covers network denial of service attacks, and demonstrates the importance of proper input validation as outlined in the OWASP Top Ten security principles.
This vulnerability highlights the critical importance of robust input validation in web applications, particularly when dealing with file system operations and directory traversal scenarios. The flaw represents a common pattern in legacy PHP applications where insufficient sanitization leads to resource exhaustion attacks that can be easily exploited by remote attackers. The impact of such vulnerabilities underscores the need for comprehensive security testing and regular patch management procedures to prevent exploitation of known weaknesses in widely deployed web applications.