A specially crafted packet can cause a denial of service on an NT 4.0 host, rendering local administration and network communication nearly unusable. This attack will crash the "services" executable, which in turn, disables the ability for the machine to perform actions via named pipes. As a consequence, users will be unable to remotely logon, logoff, manage the registry, create new file share connections, or perform remote administration. Services such as Internet Information Server may also fail to operate as expected. Rebooting the affected machine will resolve the issue, provided it is not attacked again. The problem lies within the manner that srvsvc.dll makes calls to services.exe. Certain MSRPC calls will return NULL values which are not correctly interpreted by services.exe. This, in turn, may lead to a crash of Services.exe. If this denial of service is combined with a number of other exploits, it may be possible to have this attack spawn a Debugger (ie Dr Watson) call on...
A specially crafted packet can cause a denial of service on an NT 4.0 host, rendering local administration and network communication nearly unusable. This attack will crash the "services" executable, which in turn, disables the ability for the machine to perform actions via named pipes. As a consequence, users will be unable to remotely logon, logoff, manage the registry, create new file share connections, or perform remote administration. Services such as Internet Information Server may also fail to operate as expected. Rebooting the affected machine will resolve the issue, provided it is not attacked again. The problem lies within the manner that srvsvc.dll makes calls to services.exe. Certain MSRPC calls will return NULL values which are not correctly interpreted by services.exe. This, in turn, may lead to a crash of Services.exe. If this denial of service is combined with a number of other exploits, it may be possible to have this attack spawn a Debugger (ie Dr Watson) call on the host, which, if trojaned, may execute malicious code on the target host.
