CVE-2015-2375 in Excel
Summary
by MITRE
Microsoft Excel 2010 SP2, Excel 2013 SP1, Excel 2013 RT SP1, Excel Viewer 2007 SP3, Excel Services on SharePoint Server 2010 SP2, and Excel Services on SharePoint Server 2013 SP1 allow remote attackers to bypass the ASLR protection mechanism via a crafted spreadsheet, aka "Microsoft Excel ASLR Bypass Vulnerability."
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Analysis
by VulDB Data Team • 05/31/2022
The Microsoft Excel ASLR bypass vulnerability represents a critical security flaw that undermines fundamental operating system protection mechanisms within Microsoft Office applications. This vulnerability affects multiple versions of Excel including 2010 SP2, 2013 SP1, 2013 RT SP1, Excel Viewer 2007 SP3, and Excel Services on SharePoint Server 2010 SP2 and 2013 SP1. The flaw specifically targets the Address Space Layout Randomization protection mechanism, which is designed to prevent exploitation of memory corruption vulnerabilities by randomizing the memory layout of processes. The vulnerability allows remote attackers to bypass ASLR through the manipulation of crafted spreadsheet files, effectively nullifying one of the primary defenses against buffer overflow and other memory corruption attacks.
The technical implementation of this vulnerability stems from improper handling of memory addresses within Excel's processing of spreadsheet files. When a maliciously crafted spreadsheet is opened, the application fails to properly randomize memory layouts during the execution of certain code paths, allowing attackers to predict memory addresses that would normally be randomized. This occurs through the manipulation of specific spreadsheet functions, formulas, or embedded objects that trigger code execution paths where ASLR protections are not properly enforced. The vulnerability operates at the application level rather than the operating system level, making it particularly dangerous as it leverages the trust relationship between the user and the application to bypass security protections that are typically enforced at the OS level.
The operational impact of this vulnerability extends far beyond simple privilege escalation or code execution. By bypassing ASLR, attackers gain significant advantages in exploiting additional vulnerabilities within the same application or system. This vulnerability creates a pathway for more sophisticated attacks that would otherwise be blocked by modern security mechanisms, potentially enabling attackers to execute arbitrary code, escalate privileges, or access sensitive data. The remote nature of the attack means that users can be compromised simply by opening a malicious spreadsheet file, making it particularly dangerous in enterprise environments where users frequently open documents from external sources. This vulnerability is classified under CWE-119, which addresses "Improper Restriction of Operations within the Bounds of a Memory Buffer," and aligns with ATT&CK technique T1059.005 for Command and Scripting Interpreter, as it enables attackers to establish persistent access through compromised applications.
Organizations affected by this vulnerability should implement immediate mitigations including applying the relevant Microsoft security patches, implementing application control policies to restrict execution of untrusted Office documents, and deploying network-based protections such as email filtering and web proxies that can detect and block malicious spreadsheet files. The vulnerability demonstrates the importance of maintaining up-to-date security patches and highlights the risks associated with legacy software environments that may not receive continued security support. Security teams should also consider implementing monitoring for suspicious Office document behavior and establishing incident response procedures specifically addressing this type of application-level exploit. The vulnerability serves as a reminder of the critical importance of layered security approaches and the potential for seemingly benign application functionality to be exploited as attack vectors in sophisticated cyber campaigns.