NGSSoftware Insight Security Research Advisory Name: Error logging buffer overflow in Informix Systems Affected: Informix 9.40.xC7 and xC8, 10.00.xC3 and xC4 Severity: Critical Vendor URL: http://www.ibm.com/ Author: David Litchfield [ davidl (at) ngssoftware (dot) com [email concealed] ] Date of Public Advisory: 2nd August 2006 Advisory number: #NISR02082006B CVEID: http://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2006-3854 Advisory URL: http://www.ngssoftware.com/research/ Description *********** Informix Dynamic Server is a database developed by IBM. When IBM released a patch for the overly long username buffer overflow (CVE-2006-3853) it was discovered that the patch introduced a new buffer overflow vulnerability. Details ******* If the username is longer than 32 bytes an error is logged. A message ("%s : username is longer than usersize(32).") is logged with a call to _mt_logprintf(). _mt_logprintf() creates a 960 byte buffer on the stack and then passes this as argument for the destination in a call to vsprintf(). Thus if the username is longer than 960 bytes it is possible to overflow the buffer, overwriting the saved return address, gaining control of the process' path of execution. Fix Information *************** IBM was alerted to this flaw on the 21st July 2006; a fix has now been made available - both 9.40.xC9 and 10.00.xC5 fix this issue. NGSSQuirreL for Informix, an advanced vulnerability assessment scanner designed specifically for Informix, can be used to accurately determine whether your servers are vulnerable to this flaw. More information about NGSSQuirreL for Informix can be found here http://www.ngssoftware.com/products/database-security/ngs-squirrel-infor mix.php About NGSSoftware ***************** NGSSoftware develops vulnerability assessment and compliancy tools for database servers including Oracle, Microsoft SQL Server, DB2, Sybase and Informix. Headquartered in the United Kingdom NGS has offices in London, St. Andrews (UK), Sydney, Brisbane, and Perth (Australia) and Texas in the United States; NGSConsulting provide services to some of the largest and most demanding organizations around the globe. http://www.ngssoftware.com/ Telephone +44 208 401 0070 Fax +44 208 401 0076 enquiries (at) ngssoftware (dot) com [email concealed]