CVE-2016-1857 in Safari
Summary
by MITRE
WebKit, as used in Apple iOS before 9.3.2, Safari before 9.1.1, and tvOS before 9.2.1, allows remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via a crafted web site, a different vulnerability than CVE-2016-1854, CVE-2016-1855, and CVE-2016-1856.
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Analysis
by VulDB Data Team • 08/21/2022
This vulnerability affects WebKit rendering engine implementations across multiple Apple platforms including iOS, Safari, and tvOS, representing a critical memory corruption flaw that enables remote code execution. The vulnerability stems from improper handling of memory allocation and deallocation within WebKit's JavaScript engine, specifically in how it processes certain web page elements. Attackers can craft malicious websites that trigger buffer overflows or use-after-free conditions when the browser attempts to render complex web content, particularly involving JavaScript objects and DOM manipulation. The flaw exists in the way WebKit manages memory during dynamic object creation and destruction, creating opportunities for attackers to manipulate memory pointers and execute arbitrary code with the privileges of the browser process. This vulnerability is particularly dangerous because it operates entirely within the browser context without requiring user interaction beyond visiting a malicious website, making it a prime target for drive-by attack scenarios.
The technical implementation of this vulnerability involves memory corruption patterns that align with common software security flaws categorized under CWE-125, which describes out-of-bounds read conditions, and CWE-787, which covers out-of-bounds write operations. The attack vector exploits JavaScript engine memory management by creating specific object hierarchies that cause heap corruption when the garbage collector attempts to process these structures. The vulnerability demonstrates characteristics consistent with the attacker tactics described in the MITRE ATT&CK framework under technique T1059.007 for JavaScript-based execution and T1203 for exploitation of web applications. When successful, the memory corruption allows attackers to overwrite critical memory locations including function pointers or return addresses, enabling arbitrary code execution that can bypass modern security mitigations such as ASLR and DEP.
The operational impact of CVE-2016-1857 extends beyond simple code execution to include potential system compromise and data exfiltration capabilities. Attackers leveraging this vulnerability can gain persistent access to affected systems, escalate privileges, and potentially establish backdoors for continued access. The vulnerability affects a broad user base since it targets widely used browser applications across multiple Apple platforms, making it particularly attractive for mass exploitation campaigns. Organizations and individuals using affected versions of iOS, Safari, and tvOS face significant risk of compromise, as the vulnerability operates silently in the background without user awareness. The memory corruption nature of the flaw also makes it susceptible to denial of service attacks where attackers can cause browser crashes or system instability, creating additional operational disruption. Recovery from exploitation typically requires full system reinstallation and security updates, as memory corruption can leave residual vulnerabilities that persist even after patch application.
Mitigation strategies for this vulnerability primarily focus on immediate software updates and browser security hardening measures. Apple released patches for iOS 9.3.2, Safari 9.1.1, and tvOS 9.2.1 that address the underlying memory management issues in WebKit's JavaScript engine. Organizations should implement immediate patch management protocols to ensure all affected systems receive updates promptly. Additional protective measures include browser security configuration adjustments such as disabling JavaScript for untrusted sites, implementing content security policies, and using browser sandboxing technologies. Network-level protections such as web application firewalls and intrusion detection systems can help detect and block exploitation attempts. Security monitoring should focus on unusual browser behavior, memory allocation patterns, and unexpected code execution within browser processes. Regular security assessments and penetration testing of web applications can help identify potential exploitation vectors, while user education regarding safe browsing practices remains crucial in reducing successful attack outcomes. The vulnerability serves as a reminder of the importance of maintaining current security patches and implementing layered defense strategies to protect against sophisticated browser-based attacks.