CVE-2015-8948 in libidn
Summary
by MITRE
idn in GNU 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.
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Analysis
by VulDB Data Team • 09/15/2022
The vulnerability identified as CVE-2015-8948 affects GNU libidn versions prior to 1.33, specifically within the idn component that handles internationalized domain names. This flaw represents a classic out-of-bounds read vulnerability that can be exploited by remote attackers to extract sensitive memory information through malformed input processing. The issue occurs when the library encounters a zero byte as input during the internationalized domain name processing, creating a condition where memory locations beyond the intended buffer boundaries are accessed and read.
The technical implementation of this vulnerability stems from improper input validation within the idn library's handling of zero byte sequences. When processing internationalized domain names, the library fails to properly validate the input boundaries, particularly when encountering null terminators or zero bytes in the input stream. This allows attackers to craft malicious input that triggers an out-of-bounds memory read operation, potentially exposing sensitive data from adjacent memory locations including stack contents, heap data, or other process memory segments. The vulnerability is classified under CWE-125 as an out-of-bounds read, which is a well-documented weakness in software security that can lead to information disclosure and potentially more severe exploitation vectors.
From an operational impact perspective, this vulnerability poses significant risks to systems that rely on GNU libidn for processing internationalized domain names, particularly web servers, mail systems, and any application that handles user-provided domain name input. The remote nature of the attack means that adversaries can exploit this vulnerability without requiring local access or authentication, making it particularly dangerous in networked environments. The information disclosure aspect of this vulnerability can expose sensitive system information, including cryptographic keys, passwords, or other confidential data that may be stored in adjacent memory locations. This type of information leak can facilitate further attacks by providing attackers with additional system context or credentials that could be leveraged for privilege escalation or lateral movement within a network.
The exploitation of CVE-2015-8948 aligns with ATT&CK technique T1059.007 for command and scripting interpreter, as attackers may use the leaked memory information to identify system configurations or vulnerabilities that could be exploited through command execution. Organizations using affected versions of GNU libidn should prioritize immediate patching to address this vulnerability, as the out-of-bounds read can potentially be chained with other exploitation techniques to achieve more sophisticated attacks. The remediation approach involves upgrading to GNU libidn version 1.33 or later, which includes proper input validation and boundary checking mechanisms that prevent the out-of-bounds memory access. System administrators should also implement network monitoring to detect potential exploitation attempts and consider deploying intrusion detection systems that can identify malformed domain name requests that may indicate attempted exploitation of this vulnerability.