fix(security): resolve Security-004..007 — configurable user-id attribute, DN escaping, JWT issuer/audience validation, idle-timeout preservation

This commit is contained in:
Joseph Doherty
2026-05-16 21:22:01 -04:00
parent a702cb96a8
commit 30ebbdd183
5 changed files with 383 additions and 26 deletions

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@@ -8,7 +8,7 @@
| Last reviewed | 2026-05-16 |
| Reviewer | claude-agent |
| Commit reviewed | `9c60592` |
| Open findings | 8 |
| Open findings | 4 |
## Summary
@@ -156,7 +156,7 @@ corrected to state the requirement. Regression tests
|--|--|
| Severity | Medium |
| Category | Correctness & logic bugs |
| Status | Open |
| Status | Resolved |
| Location | `src/ScadaLink.Security/LdapAuthService.cs:66`, `:138`, `:157-159` |
**Description**
@@ -176,7 +176,15 @@ consistently in both the search filter and the fallback DN. Update the XML doc t
**Resolution**
_Unresolved._
Resolved 2026-05-16 (commit `pending`). Confirmed: the search filter was hard-coded
`(uid={username})` (both in `AuthenticateAsync` and `ResolveUserDnAsync`) while the
fallback DN used `cn={username}` — the two auth modes were not interchangeable. Added
a configurable `SecurityOptions.LdapUserIdAttribute` (default `uid`) used for both the
search filter and the fallback DN via the new `BuildFallbackUserDn` helper, and
corrected the `LdapServiceAccountDn` XML doc to reference `{LdapUserIdAttribute}`.
Regression tests `BuildFallbackUserDn_UsesConfiguredUserIdAttribute`,
`BuildFallbackUserDn_HonoursNonDefaultUserIdAttribute`,
`SecurityOptions_LdapUserIdAttribute_DefaultsToUid`.
### Security-005 — DN injection in the no-service-account bind fallback
@@ -184,7 +192,7 @@ _Unresolved._
|--|--|
| Severity | Medium |
| Category | Security |
| Status | Open |
| Status | Resolved |
| Location | `src/ScadaLink.Security/LdapAuthService.cs:157-159` |
**Description**
@@ -207,7 +215,15 @@ raw DN from untrusted input is risky; restrict it or remove it.
**Resolution**
_Unresolved._
Resolved 2026-05-16 (commit `pending`). Confirmed: the fallback path interpolated
the raw `username` straight into `cn={username},{LdapSearchBase}` with no DN escaping,
and the `username.Contains('=')` shortcut let a caller supply an arbitrary bind DN.
Added an RFC 4514 `EscapeLdapDn` helper (escapes `, + " \ < > ;`, leading/trailing
space, leading `#`, NUL) applied in `BuildFallbackUserDn`, so a username such as
`victim,ou=admins` can no longer alter the DN structure. The `Contains('=')` raw-DN
shortcut was removed entirely — untrusted input no longer controls the bind identity.
Regression tests `BuildFallbackUserDn_EscapesDnMetacharacters`,
`EscapeLdapDn_EscapesAllRfc4514Specials`, `EscapeLdapDn_EscapesLeadingAndTrailingSpaces`.
### Security-006 — JWT validation disables issuer and audience checks
@@ -215,7 +231,7 @@ _Unresolved._
|--|--|
| Severity | Medium |
| Category | Security |
| Status | Open |
| Status | Resolved |
| Location | `src/ScadaLink.Security/JwtTokenService.cs:67-75`, `:56-59` |
**Description**
@@ -236,7 +252,14 @@ validation.
**Resolution**
_Unresolved._
Resolved 2026-05-16 (commit `pending`). Confirmed: `GenerateToken` set neither `iss`
nor `aud` and `ValidateToken` had `ValidateIssuer = false`/`ValidateAudience = false`.
`GenerateToken` now binds `JwtTokenService.TokenIssuer`/`TokenAudience`
(both `"scadalink-central"`) into every token, and `ValidateToken` enables
`ValidateIssuer`/`ValidateAudience` against those fixed values — a token signed with
the shared key but a foreign issuer is now rejected. Regression tests
`GenerateToken_SetsIssuerAndAudience`, `ValidateToken_RejectsTokenWithWrongIssuer`,
`ValidateToken_AcceptsOwnIssuerAndAudience`.
### Security-007 — Idle-timeout claim is reset on every token refresh
@@ -244,7 +267,7 @@ _Unresolved._
|--|--|
| Severity | Medium |
| Category | Correctness & logic bugs |
| Status | Open |
| Status | Resolved |
| Location | `src/ScadaLink.Security/JwtTokenService.cs:40`, `:111-123` |
**Description**
@@ -269,7 +292,22 @@ path agree on the semantics.
**Resolution**
_Unresolved._
Resolved 2026-05-16 (commit `pending`). Confirmed: `RefreshToken``GenerateToken`
unconditionally wrote `LastActivity = UtcNow`, so the idle clock reset on every
refresh and the documented 30-minute idle timeout could never fire for a client that
polls in the background. Implemented option (a) — the Security-side half of the
documented "15-min sliding + 30-min idle" policy (the cross-module partner of
CentralUI-005): `GenerateToken` now takes an optional `lastActivity` anchor;
`RefreshToken` carries the **existing** `LastActivity` claim forward unchanged, and a
new explicit `RecordActivity` method advances the anchor to now — to be called by the
CentralUI request pipeline on genuine user interaction (not on a background refresh).
`IsIdleTimedOut` is unchanged and now agrees with the refresh path. The remaining
CentralUI-side wiring (calling `RecordActivity` from the middleware, setting
`SlidingExpiration`/`ExpireTimeSpan`) stays tracked under CentralUI-005; this finding's
Security-side defect — the reset-on-refresh bug — is fully fixed here. Regression tests
`RefreshToken_PreservesOriginalLastActivityClaim`,
`RefreshToken_DoesNotResetIdleTimeoutWhenUserIsActuallyIdle`,
`RecordActivity_UpdatesLastActivityToNow`.
### Security-008 — N+1 query loading site-scope rules in `RoleMapper`

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@@ -18,6 +18,17 @@ public class JwtTokenService
public const string SiteIdClaimType = "SiteId";
public const string LastActivityClaimType = "LastActivity";
/// <summary>
/// Fixed issuer bound into every token and required on validation. Binding
/// issuer/audience is defence-in-depth: even though the HMAC key is shared only
/// between the two central nodes, accidental reuse of the same secret for an
/// unrelated internal token would otherwise be silently exploitable.
/// </summary>
public const string TokenIssuer = "scadalink-central";
/// <summary>Fixed audience bound into every token and required on validation.</summary>
public const string TokenAudience = "scadalink-central";
public JwtTokenService(IOptions<SecurityOptions> options, ILogger<JwtTokenService> logger)
{
_options = options?.Value ?? throw new ArgumentNullException(nameof(options));
@@ -37,11 +48,19 @@ public class JwtTokenService
}
}
/// <summary>
/// Issues a fresh JWT. <paramref name="lastActivity"/> sets the idle-timeout
/// anchor; when omitted (a brand-new login) it defaults to now. On a token
/// refresh the caller MUST pass the existing anchor forward so the idle window
/// continues to be measured from the user's last genuine activity rather than
/// from token issuance time.
/// </summary>
public string GenerateToken(
string displayName,
string username,
IReadOnlyList<string> roles,
IReadOnlyList<string>? permittedSiteIds)
IReadOnlyList<string>? permittedSiteIds,
DateTimeOffset? lastActivity = null)
{
var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_options.JwtSigningKey));
var credentials = new SigningCredentials(key, SecurityAlgorithms.HmacSha256);
@@ -50,7 +69,7 @@ public class JwtTokenService
{
new(DisplayNameClaimType, displayName),
new(UsernameClaimType, username),
new(LastActivityClaimType, DateTimeOffset.UtcNow.ToString("o"))
new(LastActivityClaimType, (lastActivity ?? DateTimeOffset.UtcNow).ToString("o"))
};
foreach (var role in roles)
@@ -67,6 +86,8 @@ public class JwtTokenService
}
var token = new JwtSecurityToken(
issuer: TokenIssuer,
audience: TokenAudience,
claims: claims,
expires: DateTime.UtcNow.AddMinutes(_options.JwtExpiryMinutes),
signingCredentials: credentials);
@@ -79,8 +100,10 @@ public class JwtTokenService
var key = new SymmetricSecurityKey(Encoding.UTF8.GetBytes(_options.JwtSigningKey));
var validationParameters = new TokenValidationParameters
{
ValidateIssuer = false,
ValidateAudience = false,
ValidateIssuer = true,
ValidIssuer = TokenIssuer,
ValidateAudience = true,
ValidAudience = TokenAudience,
ValidateLifetime = true,
ValidateIssuerSigningKey = true,
IssuerSigningKey = key,
@@ -121,6 +144,15 @@ public class JwtTokenService
return (DateTimeOffset.UtcNow - lastActivity).TotalMinutes > _options.IdleTimeoutMinutes;
}
/// <summary>
/// Issues a fresh token (new expiry, re-queried roles) while <b>preserving</b> the
/// existing <see cref="LastActivityClaimType"/> anchor. A refresh is itself
/// triggered by a request, but it must not be treated as user activity — the
/// idle window must keep being measured from the user's last genuine interaction,
/// otherwise the documented 30-minute idle timeout could never fire for a client
/// that polls in the background. Call <see cref="RecordActivity"/> to advance the
/// anchor when handling a genuine user request.
/// </summary>
public string? RefreshToken(ClaimsPrincipal currentPrincipal, IReadOnlyList<string> currentRoles, IReadOnlyList<string>? permittedSiteIds)
{
var displayName = currentPrincipal.FindFirst(DisplayNameClaimType)?.Value;
@@ -132,6 +164,36 @@ public class JwtTokenService
return null;
}
return GenerateToken(displayName, username, currentRoles, permittedSiteIds);
return GenerateToken(displayName, username, currentRoles, permittedSiteIds,
ReadLastActivity(currentPrincipal));
}
/// <summary>
/// Issues a fresh token whose <see cref="LastActivityClaimType"/> anchor is
/// advanced to now. This is the explicit "user did something" path — distinct
/// from <see cref="RefreshToken"/> — to be called by the request pipeline when
/// handling a genuine user interaction.
/// </summary>
public string? RecordActivity(ClaimsPrincipal currentPrincipal, IReadOnlyList<string> currentRoles, IReadOnlyList<string>? permittedSiteIds)
{
var displayName = currentPrincipal.FindFirst(DisplayNameClaimType)?.Value;
var username = currentPrincipal.FindFirst(UsernameClaimType)?.Value;
if (displayName == null || username == null)
{
_logger.LogWarning("Cannot record activity: missing DisplayName or Username claims");
return null;
}
return GenerateToken(displayName, username, currentRoles, permittedSiteIds,
DateTimeOffset.UtcNow);
}
private static DateTimeOffset? ReadLastActivity(ClaimsPrincipal principal)
{
var claim = principal.FindFirst(LastActivityClaimType);
return claim != null && DateTimeOffset.TryParse(claim.Value, out var value)
? value
: null;
}
}

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@@ -71,7 +71,7 @@ public class LdapAuthService
try
{
var searchFilter = $"(uid={EscapeLdapFilter(username)})";
var searchFilter = $"({_options.LdapUserIdAttribute}={EscapeLdapFilter(username)})";
var searchResults = await Task.Run(() =>
connection.Search(
_options.LdapSearchBase,
@@ -133,17 +133,13 @@ public class LdapAuthService
/// </summary>
private async Task<string> ResolveUserDnAsync(LdapConnection connection, string username, CancellationToken ct)
{
// If username already looks like a DN, use it as-is
if (username.Contains('='))
return username;
// If a service account is configured, search for the user's actual DN
if (!string.IsNullOrWhiteSpace(_options.LdapServiceAccountDn))
{
await Task.Run(() =>
connection.Bind(_options.LdapServiceAccountDn, _options.LdapServiceAccountPassword), ct);
var searchFilter = $"(uid={EscapeLdapFilter(username)})";
var searchFilter = $"({_options.LdapUserIdAttribute}={EscapeLdapFilter(username)})";
var searchResults = await Task.Run(() =>
connection.Search(
_options.LdapSearchBase,
@@ -158,13 +154,68 @@ public class LdapAuthService
return entry.Dn;
}
throw new LdapException("User not found", LdapException.NoSuchObject, $"No entry found for uid={username}");
throw new LdapException("User not found", LdapException.NoSuchObject,
$"No entry found for {_options.LdapUserIdAttribute}={username}");
}
// Fallback: construct DN directly
return string.IsNullOrWhiteSpace(_options.LdapSearchBase)
? $"cn={username}"
: $"cn={username},{_options.LdapSearchBase}";
// Fallback: construct the bind DN directly from the configured user-id
// attribute. The username is RFC 4514 DN-escaped so it cannot alter the
// DN structure (Security-005). The previous Contains('=') shortcut that
// accepted a raw caller-supplied DN has been removed — accepting an
// arbitrary DN from untrusted input let a client choose the bind identity.
return BuildFallbackUserDn(username, _options.LdapSearchBase, _options.LdapUserIdAttribute);
}
/// <summary>
/// Builds the no-service-account fallback bind DN as
/// <c>{userIdAttribute}={escaped-username}[,{searchBase}]</c>. The username is
/// escaped per RFC 4514 so DN metacharacters in untrusted input cannot inject
/// additional RDN components or change the bind identity.
/// </summary>
public static string BuildFallbackUserDn(string username, string searchBase, string userIdAttribute)
{
var rdn = $"{userIdAttribute}={EscapeLdapDn(username)}";
return string.IsNullOrWhiteSpace(searchBase) ? rdn : $"{rdn},{searchBase}";
}
/// <summary>
/// Escapes a string for use as an RFC 4514 DN attribute value: the special
/// characters <c>, + " \ &lt; &gt; ;</c> are backslash-escaped, as are a leading
/// or trailing space and a leading <c>#</c>.
/// </summary>
public static string EscapeLdapDn(string input)
{
if (string.IsNullOrEmpty(input))
return input;
var sb = new System.Text.StringBuilder(input.Length + 8);
for (var i = 0; i < input.Length; i++)
{
var c = input[i];
var isEdgeSpace = c == ' ' && (i == 0 || i == input.Length - 1);
var isLeadingHash = c == '#' && i == 0;
switch (c)
{
case ',':
case '+':
case '"':
case '\\':
case '<':
case '>':
case ';':
sb.Append('\\').Append(c);
break;
case '\0':
sb.Append("\\00");
break;
default:
if (isEdgeSpace || isLeadingHash)
sb.Append('\\');
sb.Append(c);
break;
}
}
return sb.ToString();
}
private static string EscapeLdapFilter(string input)

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@@ -37,10 +37,19 @@ public class SecurityOptions
/// <summary>
/// Service account DN for LDAP user searches (e.g., "cn=admin,dc=example,dc=com").
/// Required for search-then-bind authentication. If empty, direct bind with
/// cn={username},{LdapSearchBase} is attempted instead.
/// {LdapUserIdAttribute}={username},{LdapSearchBase} is attempted instead.
/// </summary>
public string LdapServiceAccountDn { get; set; } = string.Empty;
/// <summary>
/// LDAP attribute that identifies a user. Used both for the search-then-bind
/// filter (<c>({LdapUserIdAttribute}={username})</c>) and for constructing the
/// fallback bind DN when no service account is configured, so the two
/// authentication modes are interchangeable. Common values: <c>uid</c> (OpenLDAP),
/// <c>sAMAccountName</c> (Active Directory).
/// </summary>
public string LdapUserIdAttribute { get; set; } = "uid";
/// <summary>
/// Service account password for LDAP user searches.
/// </summary>

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@@ -475,6 +475,203 @@ public class SecurityReviewRegressionTests
#endregion
#region Code Review Regression Tests Security-004/005/006/007
/// <summary>
/// Regression tests for Security-004 (uid/cn attribute mismatch between search filter
/// and fallback DN), Security-005 (DN injection in the no-service-account fallback),
/// Security-006 (JWT issuer/audience checks disabled), and Security-007 (idle-timeout
/// claim reset on every token refresh).
/// </summary>
public class SecurityReviewRegressionTests2
{
private static SecurityOptions JwtOptions() => new()
{
JwtSigningKey = "this-is-a-test-signing-key-for-hmac-sha256-must-be-long-enough",
JwtExpiryMinutes = 15,
IdleTimeoutMinutes = 30,
JwtRefreshThresholdMinutes = 5
};
private static JwtTokenService CreateJwtService(SecurityOptions? options = null) =>
new(Options.Create(options ?? JwtOptions()), NullLogger<JwtTokenService>.Instance);
// --- Security-004: search filter and fallback DN must use the same attribute ---
[Fact]
public void BuildFallbackUserDn_UsesConfiguredUserIdAttribute()
{
// The default user-id attribute is "uid"; the fallback DN must use it,
// not a hard-coded "cn", so search-then-bind and direct-bind are interchangeable.
var dn = LdapAuthService.BuildFallbackUserDn("alice", "dc=example,dc=com", "uid");
Assert.Equal("uid=alice,dc=example,dc=com", dn);
}
[Fact]
public void BuildFallbackUserDn_HonoursNonDefaultUserIdAttribute()
{
var dn = LdapAuthService.BuildFallbackUserDn("alice", "dc=example,dc=com", "sAMAccountName");
Assert.Equal("sAMAccountName=alice,dc=example,dc=com", dn);
}
[Fact]
public void SecurityOptions_LdapUserIdAttribute_DefaultsToUid()
{
Assert.Equal("uid", new SecurityOptions().LdapUserIdAttribute);
}
// --- Security-005: DN-component escaping must be applied to the username ---
[Fact]
public void BuildFallbackUserDn_EscapesDnMetacharacters()
{
// A hostile username must not be able to alter the DN structure: the comma
// that would otherwise start a new RDN ("ou=admins") must be escaped so the
// whole string remains a single RDN value.
var dn = LdapAuthService.BuildFallbackUserDn("victim,ou=admins", "dc=example,dc=com", "uid");
Assert.Equal(@"uid=victim\,ou=admins,dc=example,dc=com", dn);
// The comma from the username is backslash-escaped, so it does not act as an
// RDN separator: the only unescaped comma is the one joining RDN and base DN.
Assert.Contains(@"victim\,ou=admins", dn);
}
[Fact]
public void EscapeLdapDn_EscapesAllRfc4514Specials()
{
var escaped = LdapAuthService.EscapeLdapDn("a,b+c\"d\\e<f>g;h");
Assert.Equal(@"a\,b\+c\""d\\e\<f\>g\;h", escaped);
}
[Fact]
public void EscapeLdapDn_EscapesLeadingAndTrailingSpaces()
{
Assert.Equal(@"\ x \ ", LdapAuthService.EscapeLdapDn(" x "));
}
// --- Security-006: JWT issuer/audience must be bound and validated ---
[Fact]
public void GenerateToken_SetsIssuerAndAudience()
{
var service = CreateJwtService();
var token = service.GenerateToken("User", "user", new[] { "Admin" }, null);
var jwt = new System.IdentityModel.Tokens.Jwt.JwtSecurityTokenHandler().ReadJwtToken(token);
Assert.Equal(JwtTokenService.TokenIssuer, jwt.Issuer);
Assert.Contains(JwtTokenService.TokenAudience, jwt.Audiences);
}
[Fact]
public void ValidateToken_RejectsTokenWithWrongIssuer()
{
// A token signed with the same key but a foreign issuer must be rejected.
var options = JwtOptions();
var key = new Microsoft.IdentityModel.Tokens.SymmetricSecurityKey(
System.Text.Encoding.UTF8.GetBytes(options.JwtSigningKey));
var creds = new Microsoft.IdentityModel.Tokens.SigningCredentials(
key, Microsoft.IdentityModel.Tokens.SecurityAlgorithms.HmacSha256);
var foreign = new System.IdentityModel.Tokens.Jwt.JwtSecurityToken(
issuer: "some-other-system",
audience: JwtTokenService.TokenAudience,
claims: new[] { new Claim(JwtTokenService.UsernameClaimType, "user") },
expires: DateTime.UtcNow.AddMinutes(10),
signingCredentials: creds);
var foreignToken = new System.IdentityModel.Tokens.Jwt.JwtSecurityTokenHandler().WriteToken(foreign);
var service = CreateJwtService(options);
Assert.Null(service.ValidateToken(foreignToken));
}
[Fact]
public void ValidateToken_AcceptsOwnIssuerAndAudience()
{
var service = CreateJwtService();
var token = service.GenerateToken("User", "user", new[] { "Admin" }, null);
Assert.NotNull(service.ValidateToken(token));
}
// --- Security-007: refresh must preserve the original LastActivity timestamp ---
[Fact]
public void RefreshToken_PreservesOriginalLastActivityClaim()
{
var service = CreateJwtService();
// Mint a token whose LastActivity is 20 minutes in the past (still inside the
// 30-minute idle window). Refresh must NOT move it forward to "now".
var staleActivity = DateTimeOffset.UtcNow.AddMinutes(-20);
var principal = new ClaimsPrincipal(new ClaimsIdentity(new[]
{
new Claim(JwtTokenService.DisplayNameClaimType, "User"),
new Claim(JwtTokenService.UsernameClaimType, "user"),
new Claim(JwtTokenService.LastActivityClaimType, staleActivity.ToString("o"))
}, "test"));
var refreshed = service.RefreshToken(principal, new[] { "Admin" }, null);
Assert.NotNull(refreshed);
var refreshedPrincipal = service.ValidateToken(refreshed!);
Assert.NotNull(refreshedPrincipal);
var claim = refreshedPrincipal!.FindFirst(JwtTokenService.LastActivityClaimType);
Assert.NotNull(claim);
Assert.True(DateTimeOffset.TryParse(claim!.Value, out var carried));
// The carried timestamp must equal the original, not "now".
Assert.True(Math.Abs((carried - staleActivity).TotalSeconds) < 2,
$"LastActivity was reset on refresh: expected ~{staleActivity:o}, got {carried:o}");
}
[Fact]
public void RefreshToken_DoesNotResetIdleTimeoutWhenUserIsActuallyIdle()
{
// A user idle for 25 of the 30-minute window: a refresh fired by some background
// request must not make IsIdleTimedOut flip back to false forever.
var service = CreateJwtService();
var staleActivity = DateTimeOffset.UtcNow.AddMinutes(-25);
var principal = new ClaimsPrincipal(new ClaimsIdentity(new[]
{
new Claim(JwtTokenService.DisplayNameClaimType, "User"),
new Claim(JwtTokenService.UsernameClaimType, "user"),
new Claim(JwtTokenService.LastActivityClaimType, staleActivity.ToString("o"))
}, "test"));
var refreshed = service.RefreshToken(principal, new[] { "Admin" }, null);
var refreshedPrincipal = service.ValidateToken(refreshed!);
// Still 25 min idle after refresh — not reset to 0.
Assert.False(service.IsIdleTimedOut(refreshedPrincipal!)); // 25 < 30, still valid
var claim = refreshedPrincipal!.FindFirst(JwtTokenService.LastActivityClaimType);
Assert.True(DateTimeOffset.TryParse(claim!.Value, out var carried));
Assert.True((DateTimeOffset.UtcNow - carried).TotalMinutes > 20,
"Refresh wrongly reset the idle clock to ~now");
}
[Fact]
public void RecordActivity_UpdatesLastActivityToNow()
{
// Genuine user activity (a real request) — distinct from a token refresh —
// updates LastActivity to the current time.
var service = CreateJwtService();
var staleActivity = DateTimeOffset.UtcNow.AddMinutes(-20);
var principal = new ClaimsPrincipal(new ClaimsIdentity(new[]
{
new Claim(JwtTokenService.DisplayNameClaimType, "User"),
new Claim(JwtTokenService.UsernameClaimType, "user"),
new Claim(JwtTokenService.LastActivityClaimType, staleActivity.ToString("o"))
}, "test"));
var touched = service.RecordActivity(principal, new[] { "Admin" }, null);
Assert.NotNull(touched);
var touchedPrincipal = service.ValidateToken(touched!);
var claim = touchedPrincipal!.FindFirst(JwtTokenService.LastActivityClaimType);
Assert.True(DateTimeOffset.TryParse(claim!.Value, out var updated));
Assert.True((DateTimeOffset.UtcNow - updated).TotalSeconds < 5,
"RecordActivity should set LastActivity to ~now");
}
}
#endregion
#region WP-9: Authorization Policy Tests
public class AuthorizationPolicyTests