CVE-2016-6262 in libidn
Summary
by MITRE
idn in libidn before 1.33 might allow remote attackers to obtain sensitive memory information by reading a zero byte as input, which triggers an out-of-bounds read, a different vulnerability than CVE-2015-8948.
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Analysis
by VulDB Data Team • 09/15/2022
The vulnerability identified as CVE-2016-6262 affects the internationalized domain names in applications library commonly known as libidn version 1.32 and earlier. This flaw represents a critical memory safety issue that can be exploited by remote attackers to potentially extract sensitive information from system memory. The vulnerability specifically manifests when the idn function processes input data containing zero bytes, creating conditions that lead to out-of-bounds memory reads. This represents a distinct vulnerability from CVE-2015-8948, which indicates that multiple memory corruption issues exist within the same library ecosystem. The affected software component plays a crucial role in handling internationalized domain names, which are essential for supporting non-ascii characters in internet domain names and is widely used across various operating systems and applications that require proper international domain name handling. The library serves as a foundational component for many network applications, web browsers, and system utilities that process domain name information, making this vulnerability particularly concerning from a security perspective.
The technical mechanism behind this vulnerability involves the improper handling of zero byte inputs within the idn function implementation. When a zero byte is encountered as input, the function fails to properly validate or sanitize the data before proceeding with memory operations. This flaw creates a scenario where the program attempts to read memory locations beyond the intended buffer boundaries, effectively triggering an out-of-bounds read condition. The root cause of this issue aligns with CWE-125, which describes out-of-bounds read vulnerabilities, and demonstrates how improper input validation can lead to memory disclosure attacks. The vulnerability is particularly dangerous because it allows attackers to potentially read arbitrary memory contents, which could include sensitive information such as cryptographic keys, passwords, session tokens, or other confidential data stored in memory. This type of memory disclosure vulnerability can provide attackers with significant information that may be used to compromise system security or facilitate further attacks.
From an operational standpoint, this vulnerability presents substantial risk to organizations that rely on libidn for processing internationalized domain names. Attackers could exploit this weakness to gain unauthorized access to sensitive memory contents, potentially compromising the confidentiality of system information. The remote nature of the attack means that exploitation does not require local system access, making it particularly dangerous for web applications, network services, and systems that process external domain name inputs. The vulnerability affects systems where libidn is integrated into applications that handle user-provided domain names, including web browsers, mail servers, DNS resolvers, and network security appliances. The impact extends beyond simple information disclosure, as the extracted memory contents could potentially reveal patterns that aid in more sophisticated attacks, including privilege escalation or additional exploitation techniques. Organizations using affected versions of libidn should consider this vulnerability as a high-priority risk requiring immediate attention.
The recommended mitigation strategy involves upgrading to libidn version 1.33 or later, which contains the necessary patches to address the out-of-bounds read vulnerability. System administrators should prioritize patching affected systems and applications that utilize libidn functionality, particularly those handling external domain name inputs. Organizations should also implement monitoring and logging to detect potential exploitation attempts, as the vulnerability may be leveraged in combination with other attack vectors. Additionally, input validation measures should be strengthened at application layers that interact with libidn functions to provide defense-in-depth protection. Security teams should consider the vulnerability in the context of broader ATT&CK framework categories related to privilege escalation and information gathering, as the memory disclosure capability could enable attackers to gather intelligence for more advanced attacks. The vulnerability also highlights the importance of proper memory management practices and input validation in security-critical libraries, serving as a reminder of the potential consequences of inadequate bounds checking in system components that handle user-provided data.