Juniper Networks SSL-VPN Client Buffer Overflow Release Date: April 25, 2006 Date Reported: February 27, 2006 Patch Development Time (In Days): 57 Days Severity: High (Remote Code Execution) Vendor: Juniper Networks Software Affected: Juniper SSL-VPN JuniperSetup Control Operating Systems Affected: Windows NT 4.0 (All versions) Windows 2000 (All versions) Windows XP (All versions) Windows 2003 (All versions) Overview: eEye Digital Security has discovered a critical vulnerability in Juniper Networks SSL-VPN Client ActiveX Control. JuniperSetup.ocx ActiveX control is automatically loaded throgh the web interface of Juniper Networks SSL-VPN. There is an exploitable buffer overflow in the handling a parameter of ActiveX control that will allow a remote attacker to reliably overwrite the stack with arbitrary data and execute arbitrary code though the web browser. Technical Details: The vulnerability exists in JuniperSetupDLL.dll which is loaded from JuniperSetup.ocx ActiveX control. If the long string is specified in the ProductName parameter as follows, the stack based buffer overflow happens in a function of JuniperSetupDLL.dll. The vulnerable function is as follows. .text:04F15783 ; int __stdcall sub_4F15783_ilvdlp(char *szProductName,LPCSTR lpValueName,LPBYTE lpData,LPDWORD lpcbData) .text:04F15783 sub_4F15783_ilvdlp proc near .text:04F15783 .text:04F15783 SubKey = byte ptr -10Ch .text:04F15783 Type = dword ptr -8 .text:04F15783 hKey = dword ptr -4 ... .text:04F157BF lea eax, [ebp+SubKey] .text:04F157C5 push offset szUninstallRegistryKey .text:04F157CA push eax .text:04F157CB call strcpy .text:04F157D0 push [ebp+szProductName] .text:04F157D3 lea eax, [ebp+SubKey] .text:04F157D9 push eax .text:04F157DA call strcat .data:04F1EA10 ; char szUninstallRegistryKey[] .data:04F1EA10 szUninstallRegistryKey db 'SOFTWAREMicrosoftWindowsCurrentVersionUninstall',0 The first argument (szProductName) of this function is the product name which is used to create the uninstall registry key. The value field of "ProductName" parameter is passed into the szProductName, copied into the local buffer "SubKey" using strcat() function without any boundary checking. So, if we pass the specially crafted "ProductName" parameter, we can overwrite the return address in the stack and execute arbitrary code. This is straight classical stack based buffer overflow vulnerability. Protection: Retina Network Security Scanner has been updated to identify this vulnerability. Blink - Endpoint Vulnerability Prevention - preemptively protects from this vulnerability. Vendor Status: Juniper Networks has released an alert (PSN-2006-03-013) and patch to address this vulnerability. Credit: Discovery: Yuji Ukai Greetings: SCS guys, they are rock ! Copyright (c) 1998-2006 eEye Digital Security Permission is hereby granted for the redistribution of this alert electronically. It is not to be edited in any way without express consent of eEye. If you wish to reprint the whole or any part of this alert in any other medium excluding electronic medium, please email alert (at) eEye (dot) com [email concealed] for permission. Disclaimer The information within this paper may change without notice. Use of this information constitutes acceptance for use in an AS IS condition. There are no warranties, implied or express, with regard to this information. In no event shall the author be liable for any direct or indirect damages whatsoever arising out of or in connection with the use or spread of this information. Any use of this information is at the user's own risk.