CVE-2014-0477 in Email::Address
Summary
by MITRE
The parse function in Email::Address module before 1.905 for Perl uses an inefficient regular expression, which allows remote attackers to cause a denial of service (CPU consumption) via an empty quoted string in an RFC 2822 address.
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Analysis
by VulDB Data Team • 12/21/2024
The vulnerability identified as CVE-2014-0477 resides within the Email::Address Perl module, specifically in its parse function implementation prior to version 1.905. This flaw represents a classic example of a regular expression denial of service attack, where an attacker can exploit inefficient pattern matching algorithms to consume excessive CPU resources. The vulnerability manifests when processing RFC 2822 compliant email addresses that contain empty quoted strings, creating a condition where the regular expression engine enters into a computationally expensive backtracking process that can effectively hang or crash the application.
The technical root cause of this vulnerability aligns with CWE-400, which catalogs weaknesses related to the lack of proper resource management and inefficient algorithmic implementations. The Email::Address module's parse function employs a regular expression pattern that exhibits exponential backtracking behavior when encountering empty quoted strings within email address syntax. This occurs because the pattern matching engine must explore numerous potential matches for the empty quoted string construct, leading to a combinatorial explosion in computational complexity. The vulnerability specifically targets the regular expression engine's handling of nested or repeated quantifiers in the context of quoted string parsing, where the pattern fails to account for the pathological case of empty quoted strings that can cause the engine to perform redundant and excessive matching operations.
From an operational perspective, this vulnerability enables remote attackers to execute denial of service attacks against systems that rely on the Email::Address module for email address validation and parsing. The impact extends beyond simple service disruption as attackers can consume significant CPU cycles with relatively simple input payloads, making this attack vector particularly effective for resource exhaustion attacks. Systems processing large volumes of email addresses or those with limited computational resources become especially vulnerable to this type of attack, as the CPU consumption can escalate rapidly and potentially affect system availability for legitimate users. The vulnerability affects any application or service that processes email addresses through the vulnerable Perl module, including web applications, email servers, and automated processing systems that depend on proper email address parsing functionality.
Mitigation strategies for CVE-2014-0477 involve immediate upgrading of the Email::Address module to version 1.905 or later, which includes fixed regular expression patterns that eliminate the backtracking vulnerability. Organizations should also implement input validation measures that sanitize email address inputs before processing them through the affected module, including rejecting or properly escaping empty quoted strings in address parsing contexts. Network-level protections can be implemented through rate limiting and resource monitoring to detect and prevent excessive CPU consumption patterns that indicate exploitation attempts. The ATT&CK framework categorizes this vulnerability under T1499.004 for Resource Exhaustion, where attackers leverage inefficient algorithms to consume system resources and cause denial of service conditions. Additionally, implementing proper logging and monitoring of CPU usage patterns during email processing can help detect exploitation attempts and provide early warning of potential attacks targeting this vulnerability.