CVE-2006-3798 in DeluxeBB
Summary
by MITRE
DeluxeBB 1.07 and earlier allows remote attackers to overwrite the (1) _GET, (2) _POST, (3) _ENV, and (4) _SERVER variables via the _COOKIE (aka COOKIE) variable, which can overwrite the other variables during an extract function call, probably leading to multiple security vulnerabilities, aka "pollution of the global namespace."
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Analysis
by VulDB Data Team • 08/01/2018
This vulnerability exists in DeluxeBB version 1.07 and earlier where the application fails to properly sanitize cookie data before processing it through an extract function. The flaw occurs when the application receives a specially crafted cookie value that contains variable assignments, which are then processed by the extract function and merged into the global namespace. This creates a dangerous situation where attacker-controlled data can overwrite critical predefined variables including _GET, _POST, _ENV, and _SERVER. The vulnerability is classified under CWE-1074 which specifically addresses the improper handling of variable extraction in PHP applications, making it a direct descendant of the broader class of insecure data handling practices that have plagued web applications for decades.
The operational impact of this vulnerability is severe as it allows remote attackers to manipulate the application's execution environment by overwriting essential server variables that are typically protected. When the extract function processes the malicious cookie data, it creates a chain reaction where legitimate application variables become contaminated with attacker-controlled values. This contamination can lead to authentication bypasses, privilege escalation, and arbitrary code execution depending on how the application utilizes these variables. The vulnerability represents a classic case of namespace pollution that can be exploited through the common technique of variable injection attacks, which aligns with ATT&CK tactics such as T1059.007 for command and script injection and T1078 for valid accounts.
The technical implementation of this vulnerability relies on PHP's extract function which can be configured to import variables from arrays or cookies into the current symbol table. When DeluxeBB processes cookies without proper sanitization, an attacker can craft a cookie value like "var1=value1&var2=value2" where the variable names match those in the global namespace. The extract function then processes this data and overwrites the predefined variables, effectively corrupting the application's operational context. This flaw demonstrates poor input validation and inadequate security controls around variable handling, creating a pathway for attackers to manipulate the application's behavior. Security practitioners should note that this vulnerability type is particularly dangerous because it affects the fundamental execution environment rather than just application data, making it a critical concern for any web application that relies on proper variable scoping and sanitization. The vulnerability's exploitation requires minimal privileges and can be accomplished through standard HTTP cookie manipulation techniques, making it particularly attractive to attackers seeking to gain unauthorized access to affected systems.