CVE-2012-4791 in Exchange
Summary
by MITRE
Microsoft Exchange Server 2007 SP3 and 2010 SP1 and SP2 allows remote authenticated users to cause a denial of service (Information Store service hang) by subscribing to a crafted RSS feed, aka "RSS Feed May Cause Exchange DoS Vulnerability."
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Analysis
by VulDB Data Team • 04/20/2021
The vulnerability identified as CVE-2012-4791 represents a significant denial of service weakness in Microsoft Exchange Server versions 2007 SP3 and 2010 SP1 and SP2. This flaw specifically targets the Information Store service component of Exchange Server, which is responsible for managing mailbox data and maintaining the core messaging infrastructure. The vulnerability arises from insufficient input validation within the RSS feed processing functionality, creating a condition where maliciously crafted RSS feeds can trigger system instability. Security researchers have classified this issue under CWE-20, which denotes improper input validation, highlighting the fundamental flaw in how the system handles external data inputs. The vulnerability operates through a carefully constructed RSS feed that, when subscribed to by authenticated users, causes the Information Store service to enter a non-responsive state, effectively rendering the affected Exchange server unable to process email requests properly.
The operational impact of this vulnerability extends beyond simple service interruption, as it can severely compromise email availability for organizations relying on Exchange Server infrastructure. When the Information Store service hangs, users experience complete email service disruption, including inability to send, receive, or access mailbox contents. The attack vector requires only authenticated access to the Exchange environment, making it particularly dangerous as it can be exploited by malicious insiders or compromised user accounts. From an attacker's perspective, this vulnerability aligns with ATT&CK technique T1499.004, which involves network denial of service attacks, specifically targeting the availability of email services. The vulnerability affects not just individual users but entire organizational email systems, potentially causing cascading effects across business operations that depend on email communication for critical functions.
Organizations affected by CVE-2012-4791 must implement immediate remediation measures to protect their Exchange Server deployments. Microsoft released security patches addressing this vulnerability through their regular update cycle, and administrators should prioritize applying the relevant security updates to all affected Exchange Server instances. Network segmentation and access control measures can provide additional defense-in-depth, limiting the potential impact of compromised accounts that might exploit this vulnerability. Monitoring systems should be configured to detect unusual RSS subscription activities or service hangs in the Information Store component. The vulnerability also underscores the importance of proper input sanitization and validation across all external data processing components, as highlighted by industry best practices for preventing similar flaws in enterprise messaging systems. Organizations should conduct regular vulnerability assessments and penetration testing to identify potential weaknesses in their Exchange Server configurations and ensure that proper security controls are in place to prevent exploitation of such denial of service conditions.