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Multiple Vulnerabilities in Apple iOS Could Allow for Arbitrary Code Execution

MS-ISAC ADVISORY NUMBER:

2021-081

DATE(S) ISSUED:

06/15/2021

OVERVIEW:

Multiple vulnerabilities have been discovered in Apple iOS that could allow for arbitrary code execution. iOS is a mobile operating system for mobile devices, including the iPhone, iPad, and iPod touch. Successful exploitation of these vulnerabilities could result in arbitrary code execution within the context of the application, an attacker gaining the same privileges as the logged-on user, or the bypassing of security restrictions. Depending on the permission associated with the application running the exploit, an attacker could then install programs; view, change, or delete data.

THREAT INTELLIGENCE:

Apple is aware that CVE-2021-30761 and CVE-2021-30762 may have been actively exploited.

SYSTEMS AFFECTED:

  • iOS versions prior to 12.5.4

RISK:

Government:

  • Large and medium government entities: HIGH
  • Small government entities: HIGH

Businesses:

  • Large and medium business entities: HIGH
  • Small business entities: HIGH

Home Users:

LOW

TECHNICAL SUMMARY:

Multiple vulnerabilities have been discovered in Apple iOS that could allow for arbitrary code execution. Details of these vulnerabilities are as follows:  
  • A memory corruption issue in the ASN.1 decoder may lead to arbitrary code execution. (CVE-2021-30737)
  • A memory corruption issue in WebKit may lead to arbitrary code execution. (CVE-2021-30761)
  • A use after free issue in WebKit may lead to arbitrary code execution. (CVE-2021-30762)
  Successful exploitation of these vulnerabilities could result in arbitrary code execution within the context of the application, an attacker gaining the same privileges as the logged-on user, or the bypassing of security restrictions. Depending on the permission associated with the application running the exploit, an attacker could then install programs; view, change, or delete data.

RECOMMENDATIONS:

We recommend the following actions be taken:
  • Apply appropriate patches provided by Apple to vulnerable systems immediately after appropriate testing.
  • Run all software as a nonprivileged user (one without administrative privileges) to diminish the effects of a successful attack.
  • Remind users not to download, accept or execute files from untrusted and unknown sources.
  • Remind users not to visit untrusted websites or follow links provided by untrusted or unknown sources.
  • Evaluate read, write, and execute permissions on all newly installed software.
  • Apply the Principle of Least Privilege to all systems and services.

REFERENCES:

Apple: https://support.apple.com/en-us/HT212548   TheHackerNews: https://thehackernews.com/2021/06/apple-issues-urgent-patches-for-2-zero.html   CVE: https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30737 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30761 https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-30762  

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