Description
A critical vulnerability has been identified in the XML parser component of Microsoft Windows, designated as CVE-2021-34448. This vulnerability involves Scripting Engine Memory Corruption, posing a significant risk to systems running the affected software configurations.
Affected Product(s)
Microsoft Windows:
- Windows 10 Version 1507
- Windows 10 Version 1607
Technical Details
The CVE-2021-34448 vulnerability, also known as Scripting Engine Memory Corruption Vulnerability, affects the Microsoft Windows Scripting Engine. This component’s primary function is to execute scripts within a web browser or other applications to automate tasks or enhance functionality. The vulnerability stems from the mishandling of objects in memory, leading to memory corruption.
Specifically, the vulnerability exists due to improper restriction of operations within the bounds of a memory buffer (CWE-119) and out-of-bounds write (CWE-787). When exploited, the vulnerability allows an attacker to execute arbitrary code within the context of the user running the affected application, such as a web browser.
Successfully exploiting this vulnerability requires the attacker to convince the user to view a specially crafted webpage or open a malicious document. The majority of the affected software configurations include various versions of Windows 10 (Versions 1507 and 1607). However, this vulnerability could be present in other versions of Windows if not properly updated.
Attackers leveraging this vulnerability typically employ social engineering techniques to lure users into interacting with malicious content, often via phishing emails or compromised websites. Threat actors targeting this vulnerability take advantage of the heap memory management of the scripting engine. By manipulating memory allocation and deallocation processes, they pave the way for the execution of malicious payloads. These payloads can lead to unauthorized access, information disclosure, or system compromise. The emergence of this vulnerability drew considerable attention from security researchers and vendors.
Microsoft’s patching efforts notably culminated in several security updates addressing the issue. These updates, such as KB5004289, KB5004298, and KB5004305, were released to plug the security holes in affected systems. Incidentally, this vulnerability was part of a broader set of security flaws fixed during Microsoft’s regular Patch Tuesday release cycle. In July 2021 alone, Microsoft documented 117 vulnerabilities, with 17 marked as critical. These included vulnerabilities in products like Microsoft Office, Microsoft Exchange Server, Bing, SharePoint Server, Internet Explorer, Visual Studio, and OpenEnclave.
The CVE-2021-34448 vulnerability is particularly dangerous because drive-by attacks can exploit it. In such scenarios, users merely need to visit a compromised or malicious website for their systems to be infected. This kind of attack does not require significant user interaction beyond accessing the website, making it an efficient method for attackers to distribute malware. Further compounding the risk is the publicly known exploit status of this vulnerability.
Cybersecurity advisories outlined that three vulnerabilities, including CVE-2021-34448, were actively being exploited in real-world attacks before the patches were issued. These attacks often go unnoticed by end-users until consequential damage or system anomalies are detected. The prompt release of security patches underscores the urgency communicated by Microsoft and other security experts. By applying these patches, users protect their systems from the elevated risks posed by this vulnerability and mitigate the potential for future exploit attempts. Users are encouraged to expedite the application of these patches to maintain the security and integrity of their systems.
Weakness
The weaknesses associated with CVE-2021-34448 include: – Improper Restriction of Operations within the Bounds of a Memory Buffer (CWE-119) – Out-of-bounds Write (CWE-787) These weaknesses arise when the Scripting Engine fails to handle memory operations correctly, leading to memory corruption that attackers can exploit to execute arbitrary code.
Impact Assessment
If exploited, this vulnerability could allow an attacker to:
- Gain unauthorized access to sensitive data
- Execute arbitrary code on the affected system
- Potentially take complete control over the system, depending on the user’s privileges The attacker could install programs, view, change, or delete data, and create new accounts with full user rights, leading to severe security breaches and data integrity issues.
Active Exploitation
Active exploitations of CVE-2021-34448 have been reported. The vulnerability was actively being exploited in the wild before the release of the patch. Attackers used this exploit to conduct drive-by attacks via web browsers, prompting users to visit specially crafted malicious web pages. This activity aligns with the patterns observed in known adversary groups that frequently target similar vulnerabilities to gain unauthorized access and control over systems.
Ransomware Association
There is a potential association between this vulnerability and ransomware attacks. Exploiting CVE-2021-34448 could serve as an initial access vector for ransomware groups to infiltrate and compromise systems, leading to subsequent encryption of files and ransom demands.
Mitigation and Resolution
We have released a patch that addresses this vulnerability. Please update to version 10.0.10240.19003 (for Windows 10 Version 1507) and version 10.0.14393.4530 (for Windows 10 Version 1607) immediately. The patches are part of Microsoft’s security updates mentioned in KB5004289, KB5004298, KB5004305, and other referenced updates. Applying these updates will mitigate the risk posed by this vulnerability.
Recommendations
- We strongly recommend all customers apply the latest patch as soon as possible.
- Users can apply the patch by navigating to Start > Settings > Update & Security > Windows Update, then selecting “Check for updates” and applying any available updates.
- Visit the Microsoft Update Catalog to download and install the specific updates related to CVE-2021-34448.
- Ensure antivirus and antimalware solutions are up-to-date to detect any exploits targeting this vulnerability.
- Educate users on the risks of interacting with suspicious emails, links, or websites to reduce the likelihood of social engineering attacks.
- Regularly back up critical data to minimize data loss in case of compromise.
References
- Microsoft Update Guide for CVE-2021-34448
- Microsoft Security Guidance for CVE-2021-34448
- CVE MITRE Details
- National Vulnerability Database
- Zero Day Vulnerability Database
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