Question

I have a piece of code that attempts to acquire the credentials for a user on a remote computer which I cant get working. currently this produces an access violation error (0xc0000005) when run:

SEC_WINNT_AUTH_IDENTITY_W identity;
ZeroMemory(&identity, sizeof(identity));

identity.Domain = (unsigned short *)_T("DOMAIN");
identity.DomainLength = lstrlenW(_T("DOMAIN"));
identity.User = (unsigned short *)_T("USER");
identity.UserLength = lstrlenW(_T("USER"));
identity.Password = (unsigned short *)_T("PASS");
identity.PasswordLength = lstrlenW(_T("PASS"));
identity.Flags = SEC_WINNT_AUTH_IDENTITY_UNICODE;

PCredHandle credentials = NULL;
PTimeStamp credentialsExpiry = NULL;

SECURITY_STATUS result = AcquireCredentialsHandleW(_T("USER"), _T("NTLM"), SECPKG_CRED_OUTBOUND, NULL, &identity, NULL, NULL, credentials, credentialsExpiry);

and i have no idea why. any assistance would be very welcome.

Answer 1

You need to change the last section of code to look like this:

CredHandle credentials;
TimeStamp credentialsExpiry;

SECURITY_STATUS result = AcquireCredentialsHandleW(_T("USER"), _T("NTLM"), 
    SECPKG_CRED_OUTBOUND, NULL, &identity, NULL, NULL, 
    &credentials, &credentialsExpiry);

Per MSDN docs, the pointers in the last 2 parameters are not optional on your call:

phCredential [out]

A pointer to a
CredHandle structure to receive the
credential handle.

ptsExpiry [out]

A pointer to a
TimeStamp structure that receives the
time at which the returned credentials
expire. The value returned in this
TimeStamp structure depends on the
security package. The security package
must return this value in local time.

This parameter is set to a constant
maximum time. There is no expiration
time for Digest security contexts or
credentials or when using the Digest
SSP.

When using the Schannel SSP, this
parameter is optional. When the
credential to be used for
authentication is a certificate, this
parameter receives the expiration time
for that certificate. If no
certificate was supplied, then a
maximum time value is returned.