CVE-2018-11236 in Enterprise Session Border Controller
Summary
by MITRE
stdlib/canonicalize.c in the GNU C Library (aka glibc or libc6) 2.27 and earlier, when processing very long pathname arguments to the realpath function, could encounter an integer overflow on 32-bit architectures, leading to a stack-based buffer overflow and, potentially, arbitrary code execution.
If you want to get best quality of vulnerability data, you may have to visit VulDB.
Analysis
by VulDB Data Team • 08/29/2023
The vulnerability identified as CVE-2018-11236 represents a critical security flaw within the GNU C Library implementation of the realpath function. This issue specifically affects glibc versions 2.27 and earlier, where the canonicalize.c component fails to properly handle extremely long pathname arguments. The flaw manifests as an integer overflow condition that occurs exclusively on 32-bit architectural systems, creating a cascading security risk that can potentially lead to arbitrary code execution.
The technical implementation of this vulnerability stems from improper bounds checking within the realpath function's canonicalization process. When processing pathnames that exceed normal length parameters, the function performs calculations that can overflow 32-bit integer variables, causing the stack buffer to be allocated with insufficient space. This integer overflow occurs during the computation of buffer sizes needed for pathname resolution, where the calculation wraps around to a much smaller value than intended. The resulting stack-based buffer overflow allows attackers to overwrite adjacent memory locations, potentially corrupting program execution flow and enabling code injection attacks.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to encompass full system compromise on affected 32-bit systems. Attackers exploiting this flaw can manipulate the stack layout to inject malicious code, bypassing typical security mitigations such as stack canaries and address space layout randomization. The vulnerability is particularly dangerous because it requires no special privileges to exploit, making it accessible to unauthenticated attackers who can trigger the condition through crafted pathname inputs. This makes the vulnerability highly attractive for exploitation in environments where 32-bit glibc implementations remain in use.
Mitigation strategies for CVE-2018-11236 primarily focus on immediate system updates and architectural considerations. The most effective solution involves upgrading to glibc versions 2.28 or later where the integer overflow has been properly addressed through enhanced input validation and buffer size calculations. Organizations should also implement input sanitization measures at application layers to prevent excessively long pathnames from reaching the realpath function. Additionally, system administrators should consider disabling unnecessary use of realpath in applications where path canonicalization is not strictly required. This vulnerability aligns with CWE-190, Integer Overflow or Wraparound, and maps to ATT&CK technique T1059.007 for execution through command-line interfaces where the vulnerable function might be invoked.
The broader implications of this vulnerability highlight the ongoing challenges in maintaining secure system libraries, particularly when legacy 32-bit architectures continue to be deployed in production environments. The flaw demonstrates how seemingly minor implementation details in core system components can create significant security risks, emphasizing the importance of thorough testing and validation of library functions that handle user input. Security teams should prioritize identification of systems running affected glibc versions and implement comprehensive patch management programs to address this and similar vulnerabilities in system libraries.