[FD] DefenseCode Security Advisory: IBM Informix DB-Access Buffer Overflow

DefenseCode Security Advisory IBM Informix DB-Access Buffer Overflow Advisory ID: DC-2017-04-001 Advisory Title: IBM Informix DB-Access Buffer Overflow Advisory URL: http://ift.tt/2t978wz Software: IBM Informix Version: 12.10 Vendor Status: Vendor Contacted / Not Fixed Release Date: 11.07.2017 Risk: High 1. General Overview =================== IBM Informix DB-Access utility is vulnerable to a stack based buffer overflow, caused by improper bounds checking which could allow an attacker to execute arbitrary code. The vulnerability is triggered by providing an overly long file parameter value inside a LOAD statement, which is used to insert data from an operating-system file into an existing table or view. 2. Software Overview =================== Informix is one of the world’s most widely used database servers with users ranging from the world’s largest corporations to start-ups. IBM Informix incorporates design concepts that are significantly different from traditional relational platforms, resulting in extremely high levels of performance and availability, distinctive capabilities in data replication and scalability, and minimal administrative overhead. The DB-Access utility is included with the Informix server and with the Informix Client Software Development Kit. DB-Access provides a menu-driven interface for entering, running, and debugging SQL statements and Stored Procedure Language routines. DB-Access can also be ran interactively from the command line. 3. Brief Vulnerability Description ================================== By providing a specially crafted command file to the DB-Access command line utility it is possible to cause a buffer overflow, overwriting the instruction pointer (EIP) and thus hijack the execution flow of the program. Crafted file contains a LOAD statement with an overly long file parameter that will overwrite EIP. 3.1 Proof of Concept The following python script will generate a proof of concept .sql crash test file that can be used to verify the vulnerability:

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