CVE-2016-5041 in libdwarf
Summary
by MITRE
dwarf_macro5.c in libdwarf before 20160923 allows remote attackers to cause a denial of service (NULL pointer dereference) via a debugging information entry using DWARF5 and without a DW_AT_name.
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Analysis
by VulDB Data Team • 08/28/2020
The vulnerability identified as CVE-2016-5041 represents a critical denial of service flaw within the libdwarf library version prior to 20160923. This issue specifically affects the dwarf_macro5.c component and occurs when processing debugging information entries that utilize DWARF5 format without including the DW_AT_name attribute. The flaw manifests as a NULL pointer dereference, which can be exploited by remote attackers to crash applications that rely on libdwarf for processing debug information. The vulnerability is particularly concerning because it can be triggered through malformed debugging data that might be encountered during normal program execution or during debugging operations.
The technical root cause of this vulnerability stems from insufficient input validation within the libdwarf library's handling of DWARF5 debugging entries. When the library encounters a debugging information entry that conforms to the DWARF5 standard but lacks the mandatory DW_AT_name attribute, the code path fails to properly check for null pointers before dereferencing them. This type of flaw falls under CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations. The vulnerability exists because the library does not adequately validate the presence and correctness of required debugging attributes before attempting to process them, creating a scenario where uninitialized or null pointers are accessed during normal operation.
From an operational perspective, this vulnerability poses significant risks to systems that utilize libdwarf for processing debug information, particularly in environments where applications might encounter untrusted debugging data. The denial of service impact means that remote attackers can cause applications to crash or become unresponsive, potentially leading to service disruption for legitimate users. This vulnerability is particularly dangerous in server environments where applications might process debugging information from multiple sources, or in security-sensitive applications that rely on stable debugging infrastructure. The attack vector is remote, meaning that malicious actors can trigger the vulnerability without requiring local access to the system, making it a high-severity threat in networked environments.
The impact of this vulnerability extends beyond simple service disruption as it can be leveraged as part of broader attack strategies within the adversary lifecycle defined by ATT&CK framework. Specifically, this flaw can be categorized under the T1499.004 technique related to Network Denial of Service, where attackers can exploit the NULL pointer dereference to maintain persistent service disruption. Organizations utilizing libdwarf in their debugging infrastructure should consider this vulnerability as part of their broader security posture assessment, particularly in systems where debugging information might be processed from untrusted sources. The vulnerability demonstrates the importance of proper input validation and error handling in security-critical libraries that process structured data formats.
Mitigation strategies for CVE-2016-5041 primarily involve updating to libdwarf version 20160923 or later, which contains the necessary patches to address the NULL pointer dereference issue. System administrators should also implement monitoring for applications that utilize libdwarf to detect potential exploitation attempts and ensure that debugging information processing is properly sandboxed when dealing with untrusted data. Additionally, organizations should consider implementing input validation mechanisms that can detect and reject malformed debugging entries before they reach the vulnerable library code, providing defense-in-depth protection against similar vulnerabilities in other components. The fix implemented in the patched version demonstrates proper error handling and validation of debugging attributes, ensuring that the library gracefully handles missing or malformed DW_AT_name attributes without crashing.