CVE-2017-1310 in Informix Dynamic Server
Summary
by MITRE
IBM Informix Dynamic Server 12.1 could allow an authenticated user to cause a buffer overflow that would write large assertion fail files to the server. Done enough times, this could use large parts of the file system and cause the server to crash. IBM X-Force ID: 125569.
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Analysis
by VulDB Data Team • 12/30/2020
IBM Informix Dynamic Server version 12.1 contains a buffer overflow vulnerability that affects authenticated users with the ability to trigger assertion failures within the system. This vulnerability stems from insufficient bounds checking when processing assertion failure messages, allowing an attacker to write excessively large assertion fail files to the server's file system. The flaw manifests when the system encounters assertion failures and attempts to log them to disk, where the buffer allocated for storing these messages does not adequately account for the potential size of the assertion data being processed. The vulnerability operates under the Common Weakness Enumeration category of buffer overflow, specifically classified as CWE-121 which represents stack-based buffer overflow conditions.
The operational impact of this vulnerability extends beyond simple resource consumption, as repeated exploitation can lead to significant system instability and potential denial of service conditions. When assertion failure files grow excessively large, they consume substantial disk space on the server, potentially exhausting available storage capacity and causing the Informix Dynamic Server to crash or become unresponsive. The vulnerability's exploitation pattern requires authentication to the system, which reduces the attack surface but does not eliminate the risk entirely, as authenticated users with malicious intent can leverage this weakness. The attack vector involves triggering assertion failures through specific database operations or queries that cause the server to generate oversized log entries, with each successful exploitation contributing to progressive file system degradation.
Security practitioners should consider this vulnerability in the context of the MITRE ATT&CK framework, particularly under the Tactic of Defense Evasion and the technique of Resource Exhaustion, where the system's ability to maintain normal operations is compromised through excessive resource consumption. The vulnerability's exploitation aligns with the concept of persistent denial of service, where an attacker can systematically consume system resources until the server becomes unavailable. IBM has released patches addressing this issue in subsequent versions of the Informix Dynamic Server, and organizations should prioritize upgrading to patched versions to mitigate this risk. Additionally, implementing monitoring for unusual disk space consumption patterns and assertion failure logging activities can help detect potential exploitation attempts.
The technical flaw represents a classic buffer management issue where the system fails to properly validate input size before writing to allocated buffers, creating a scenario where the assertion failure logging mechanism can be abused to consume excessive storage resources. This vulnerability highlights the importance of proper input validation and resource management in database server applications, particularly in systems that generate extensive logging information during error conditions. Organizations should also consider implementing disk space monitoring and automated alerts to prevent complete system exhaustion, while ensuring that logging configurations are appropriately sized to handle normal operational loads without creating exploitable conditions. The vulnerability's impact is amplified in environments where disk space is limited or where automated backup processes might be disrupted by the excessive file growth.