CVE-2021-47155 in Net::IPV4Addr
Summary
by MITRE • 03/18/2024
The Net::IPV4Addr module 0.10 for Perl does not properly consider extraneous zero characters in an IP address string, which (in some situations) allows attackers to bypass access control that is based on IP addresses.
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Analysis
by VulDB Data Team • 08/30/2024
The vulnerability identified as CVE-2021-47155 affects the Net::IPV4Addr Perl module version 0.10, presenting a significant security risk through improper handling of IP address string parsing. This module is commonly used in Perl applications for IPv4 address manipulation and validation, making it a critical component in network security implementations. The flaw stems from the module's failure to properly normalize IP address strings when extraneous zero characters are present, creating potential bypass opportunities for malicious actors seeking to circumvent IP-based access controls.
The technical implementation of this vulnerability resides in the module's IP address parsing logic where leading zeros in IP address octets are not consistently handled according to standard IPv4 address conventions. In traditional IPv4 addressing, leading zeros should be ignored or normalized, but the Net::IPV4Addr module fails to perform this normalization consistently across all parsing scenarios. This inconsistency allows attackers to craft IP address strings that appear valid but contain extraneous zero characters, potentially enabling them to bypass security measures that rely on exact IP address matching or subnet-based access controls.
From an operational impact perspective, this vulnerability directly undermines the integrity of IP-based access control systems that depend on the Net::IPV4Addr module for address validation. Attackers can exploit this weakness to gain unauthorized access to systems, services, or resources that should be restricted to specific IP addresses or ranges. The vulnerability is particularly concerning in environments where network segmentation relies on IP address filtering, firewall rules, or application-level access controls that use this module for validation. The bypass potential creates a scenario where an attacker might be able to access restricted resources by simply modifying their IP address string to include extraneous zeros in the octet representation.
Security professionals should note that this vulnerability aligns with CWE-180, which addresses the issue of incorrect behavior when handling input data that contains extraneous or ambiguous representations. The flaw also relates to ATT&CK technique T1078.002, which covers legitimate credentials obtained through network service exploitation, as this vulnerability enables unauthorized access through malformed IP address manipulation. Organizations using this module in production environments should immediately assess their exposure and implement mitigation strategies. The recommended approach includes upgrading to a patched version of the Net::IPV4Addr module, implementing additional input validation layers, and conducting comprehensive security reviews of all IP-based access control implementations that utilize this vulnerable component. Additionally, network administrators should consider implementing supplementary security controls such as multi-factor authentication or more robust access control mechanisms that are not solely dependent on IP address validation.