CVE-2016-4748 in macOS
Summary
by MITRE
Perl in Apple OS X before 10.12 allows local users to bypass the taint-mode protection mechanism via a crafted environment variable.
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Analysis
by VulDB Data Team • 09/21/2022
The vulnerability identified as CVE-2016-4748 represents a critical security flaw in Perl's implementation within Apple macOS versions prior to 10.12. This issue specifically targets the taint-mode protection mechanism that Perl employs to prevent potentially dangerous operations when data originates from external sources. The flaw allows local attackers to bypass these essential security protections through the manipulation of environment variables, effectively undermining the sandboxing and input validation measures designed to protect against code injection and privilege escalation attacks.
The technical exploitation of this vulnerability occurs through the careful crafting of environment variables that can manipulate Perl's internal state and bypass the taint-mode checks. When Perl operates in taint mode, it should reject any data that originates from external sources to prevent malicious code execution. However, the flaw in Apple's Perl implementation allows attackers to craft environment variables that can circumvent these checks, potentially enabling arbitrary code execution or privilege escalation. This represents a fundamental failure in the security model that Perl implements for protecting against tainted data manipulation.
From an operational impact perspective, this vulnerability creates significant risks for macOS systems running affected versions of Perl. Local users who can manipulate environment variables can effectively bypass the security protections that should prevent malicious code execution. The vulnerability is particularly concerning because it operates at the system level within Perl's core functionality, making it difficult to detect and mitigate without proper system updates. The attack vector requires local system access but does not require network connectivity, making it a persistent threat that can be exploited by malware or compromised user accounts.
The mitigation strategy for this vulnerability involves upgrading to Apple macOS 10.12 or later, which includes patched versions of Perl that properly enforce taint-mode protections. System administrators should also consider implementing additional security measures such as monitoring for unusual environment variable modifications and restricting local user privileges where possible. The vulnerability aligns with CWE-254, which describes weaknesses in protection mechanisms, and relates to ATT&CK technique T1059.007 for command and scripting interpreter, as it enables attackers to bypass security protections and execute malicious code through Perl's interpreted environment. Organizations should prioritize patch management to ensure all affected systems receive the necessary updates to address this security flaw and prevent potential exploitation by adversaries seeking to leverage local privilege escalation opportunities.