CVE-2007-3527 in SQL Server
Summary
by MITRE
Integer overflow in Firebird 2.0.0 allows remote authenticated users to cause a denial of service (CPU consumption) via certain database operations with multi-byte character sets that trigger an attempt to use the value 65536 for a 16-bit integer, which is treated as 0 and causes an infinite loop on zero-length data.
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Analysis
by VulDB Data Team • 07/08/2019
The vulnerability described in CVE-2007-3527 represents a critical integer overflow flaw within the Firebird database management system version 2.0.0 that specifically affects applications utilizing multi-byte character sets. This issue stems from improper handling of integer values during database operations, creating a scenario where legitimate authenticated users can exploit the system to consume excessive CPU resources and potentially cause system-wide denial of service conditions. The flaw manifests when database operations process multi-byte character data, particularly in scenarios where character encoding requires extended byte sequences that trigger the problematic integer arithmetic.
The technical root cause of this vulnerability lies in the improper validation and handling of 16-bit integer values within the Firebird database engine's character set processing routines. When processing multi-byte character data, the system attempts to calculate and utilize a value of 65536, which exceeds the maximum representable value for a 16-bit signed integer (32767) or unsigned integer (65535). This overflow condition causes the system to treat the value as 0, which subsequently triggers an infinite loop when processing zero-length data structures. The vulnerability operates under CWE-190, which classifies integer overflow conditions that can lead to unpredictable behavior and system instability. The specific implementation flaw occurs in the database engine's handling of character set conversion and buffer management, where the overflow results in a logical error that disrupts normal program execution flow.
The operational impact of this vulnerability extends beyond simple resource consumption to encompass potential system instability and service disruption for legitimate users. Remote authenticated attackers can exploit this condition to cause sustained high CPU utilization, effectively rendering the database service unavailable to other users while consuming significant system resources. The infinite loop created by the zero-length data processing causes the database engine to continuously iterate through a problematic code path, leading to resource exhaustion and denial of service conditions. This vulnerability particularly affects database systems that handle international character sets and multilingual data processing, making it especially relevant in global enterprise environments where multi-byte character support is essential. The impact aligns with ATT&CK technique T1499.004, which involves network denial of service attacks through resource exhaustion, and demonstrates how seemingly benign database operations can be weaponized for system disruption.
Mitigation strategies for this vulnerability require immediate patching of the Firebird database system to the corrected version that properly handles integer overflow conditions in character set processing. Organizations should implement network segmentation and access controls to limit authentication access to database systems until patches are applied, while monitoring for unusual CPU consumption patterns that may indicate exploitation attempts. System administrators should also consider implementing resource limits and process monitoring to detect and mitigate the effects of the infinite loop behavior. The vulnerability serves as a reminder of the importance of proper integer boundary checking in database systems and highlights the need for comprehensive input validation, particularly when handling multi-byte character data that may trigger unexpected arithmetic conditions. Security teams should also review and test database configurations to ensure that character set handling routines do not introduce similar overflow conditions in other system components, as this type of flaw can potentially exist in various parts of database processing pipelines.