CVE-2018-12558 in Email::Address
Summary
by MITRE
The parse() method in the Email::Address module through 1.909 for Perl is vulnerable to Algorithmic complexity on specially prepared input, leading to Denial of Service. Prepared special input that caused this problem contained 30 form-field characters ("\f").
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Analysis
by VulDB Data Team • 03/28/2023
The vulnerability identified as CVE-2018-12558 affects the Email::Address Perl module version 1.909 and earlier, representing a significant security concern related to algorithmic complexity and resource exhaustion. This flaw exists within the parse() method of the module, which is commonly used for parsing email addresses in Perl applications. The vulnerability arises from the module's inability to efficiently handle specially crafted input that contains a specific pattern of form-field characters, specifically 30 consecutive form-feed characters represented as " ". The issue demonstrates how seemingly benign parsing operations can become vectors for denial of service attacks when input validation is inadequate.
The technical implementation of this vulnerability stems from the module's parsing algorithm exhibiting quadratic or worse time complexity when processing the malformed input. When the parse() method encounters the specially prepared input containing 30 form-field characters, the internal parsing logic becomes susceptible to algorithmic complexity attacks where the computational resources required to process the input grow exponentially rather than linearly. This behavior aligns with CWE-400, which categorizes algorithmic complexity vulnerabilities as a significant risk for denial of service conditions. The attack vector specifically targets the parsing routine's handling of control characters within email address formats, exploiting the module's lack of input sanitization or complexity bounds checking.
The operational impact of this vulnerability extends beyond simple service disruption to potentially affect any application or system that relies on the Email::Address module for email parsing operations. Attackers can exploit this weakness by providing maliciously crafted email addresses containing the specific form-field character pattern, causing the target system to consume excessive CPU cycles and memory resources. This leads to denial of service conditions where legitimate users cannot access services due to the system being overwhelmed by the resource-intensive parsing operation. The vulnerability particularly affects web applications, email processing systems, and any Perl-based infrastructure that accepts user-provided email addresses without proper validation, creating a widespread risk across numerous deployment scenarios.
Mitigation strategies for CVE-2018-12558 should focus on immediate patching of the Email::Address module to version 1.910 or later, which contains the necessary fixes for the algorithmic complexity issue. Organizations should implement input validation measures that limit the length and complexity of email addresses processed by their applications, particularly when dealing with user-submitted data. The implementation of resource limits and timeout mechanisms can help prevent exploitation by limiting the computational resources available to parsing operations. Additionally, monitoring systems should be deployed to detect unusual parsing patterns that might indicate attempted exploitation of this vulnerability. From an ATT&CK framework perspective, this vulnerability maps to T1499.004 which covers network denial of service attacks, and T1070.004 which involves indicator removal on hosted systems. Organizations should also consider implementing web application firewalls that can detect and block malicious email address patterns, as well as regular security testing that includes fuzzing of input parsing functions to identify similar vulnerabilities in other components.