NT IIS Malformed HTTP Request Header DoS Vulnerability

Bugtraq ID:	579
Class:	Failure to Handle Exceptional Conditions
CVE:
Remote:	Yes
Local:	Yes
Published:	Aug 11 1999 12:00AM
Updated:	Aug 11 1999 12:00AM
Credit:	Reported to Microsoft by Nobuo Miwa <[email protected]>. Microsoft Security Bulletin MS99-029 released August 11, 1999.
Vulnerable:	Microsoft Site Server Commerce Edition 3.0 i386 + Hancom Hancom Office 2007 0 - Microsoft BackOffice 4.5 - Microsoft BackOffice 4.5 + Microsoft Commercial Internet System 2.0 + Microsoft Site Server Commerce Edition 3.0 alpha - Microsoft Windows NT Enterprise Server 4.0 SP6a - Microsoft Windows NT Enterprise Server 4.0 SP6a - Microsoft Windows NT Enterprise Server 4.0 SP6 - Microsoft Windows NT Enterprise Server 4.0 SP6 - Microsoft Windows NT Enterprise Server 4.0 SP5 - Microsoft Windows NT Enterprise Server 4.0 SP5 - Microsoft Windows NT Enterprise Server 4.0 SP4 - Microsoft Windows NT Enterprise Server 4.0 SP4 - Microsoft Windows NT Enterprise Server 4.0 SP3 - Microsoft Windows NT Enterprise Server 4.0 SP3 - Microsoft Windows NT Server 4.0 SP6a - Microsoft Windows NT Server 4.0 SP6a - Microsoft Windows NT Server 4.0 SP6 - Microsoft Windows NT Server 4.0 SP6 - Microsoft Windows NT Server 4.0 SP5 - Microsoft Windows NT Server 4.0 SP5 - Microsoft Windows NT Server 4.0 SP4 - Microsoft Windows NT Server 4.0 SP4 - Microsoft Windows NT Server 4.0 SP3 - Microsoft Windows NT Server 4.0 SP3 Microsoft Site Server Commerce Edition 3.0 alpha - Microsoft BackOffice 4.5 - Microsoft BackOffice 4.5 - Microsoft IIS 4.0 - Microsoft Windows NT 4.0 - Microsoft Windows NT Enterprise Server 4.0 SP6a - Microsoft Windows NT Enterprise Server 4.0 SP6a - Microsoft Windows NT Enterprise Server 4.0 SP6 - Microsoft Windows NT Enterprise Server 4.0 SP6 - Microsoft Windows NT Enterprise Server 4.0 SP5 - Microsoft Windows NT Enterprise Server 4.0 SP5 - Microsoft Windows NT Enterprise Server 4.0 SP4 - Microsoft Windows NT Enterprise Server 4.0 SP4 - Microsoft Windows NT Enterprise Server 4.0 SP3 - Microsoft Windows NT Enterprise Server 4.0 SP3 - Microsoft Windows NT Server 4.0 SP6a - Microsoft Windows NT Server 4.0 SP6a - Microsoft Windows NT Server 4.0 SP6 - Microsoft Windows NT Server 4.0 SP6 - Microsoft Windows NT Server 4.0 SP5 - Microsoft Windows NT Server 4.0 SP5 - Microsoft Windows NT Server 4.0 SP4 - Microsoft Windows NT Server 4.0 SP4 - Microsoft Windows NT Server 4.0 SP3 - Microsoft Windows NT Server 4.0 SP3 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 Commercial Internet System 2.5 Microsoft Commercial Internet System 2.0
Not Vulnerable:

NT IIS Malformed HTTP Request Header DoS Vulnerability

Quoted from Nobuo Miwa's post to Bugtraq:

Simple play. I sent lots of "Host:aaaaa...aa" to IIS like...

GET / HTTP/1.1
Host: aaaaaaaaaaaaaaaaaaaaaaa....(200 bytes)
Host: aaaaaaaaaaaaaaaaaaaaaaa....(200 bytes)
...10,000 lines
Host: aaaaaaaaaaaaaaaaaaaaaaa....(200 bytes)

I sent twice above request sets. Then somehow victim IIS got memory leak after these requests. Of course, it can not respond any request any more. If you try this, you should see memory increase through performance monitor. You would see memory increase even after those requests finished already. It will stop when you got shortage of virtual memory. After that, you might not be able to restart web service and you would restart computer. I tried this against Japanese and English version of Windows NT.

NT IIS Malformed HTTP Request Header DoS Vulnerability

Solution:
Microsoft released a patch for this vulnerability on August 11, 1999. However, on August 12, 1999 they retracted it due to an error that made IIS hang whenever the logfile was an exact multiple of 64KB. Microsoft re-released the bulletin on August 16, 1999. The new patches are available at:
ftp://ftp.microsoft.com/bussys/iis/iis-public/fixes/usa/security/HDBRK-fix/

NT IIS Malformed HTTP Request Header DoS Vulnerability

References:

• Frequently Asked Questions: Microsoft Security Bulletin (MS99-029) (Microsoft)
  
• Q238349: Specially-Malformed Header in GET Request Creates Denial of Service (Microsoft)