PowerShell secret masking (#1258)

* Trim pwsh special chars when masking secrets

* Add pwsh valueEncoder

* Explain regex

* Update ValueEncoders.cs

* Add tests for pwsh color codes in secrets

* Formatting

* Group tests into theories

* Split secret on PS chars and mask for them

* Clean up comments

* Remove unused unittest

* Rename escape methods

src/Runner.Common/HostContext.cs

@@ -90,6 +90,8 @@ namespace GitHub.Runner.Common
             this.SecretMasker.AddValueEncoder(ValueEncoders.UriDataEscape);
             this.SecretMasker.AddValueEncoder(ValueEncoders.XmlDataEscape);
             this.SecretMasker.AddValueEncoder(ValueEncoders.TrimDoubleQuotes);
+            this.SecretMasker.AddValueEncoder(ValueEncoders.PowerShellPreAmpersandEscape);
+            this.SecretMasker.AddValueEncoder(ValueEncoders.PowerShellPostAmpersandEscape);
 
             // Create the trace manager.
             if (string.IsNullOrEmpty(logFile))

src/Sdk/DTLogging/Logging/ValueEncoders.cs

@@ -2,6 +2,7 @@
 using System.ComponentModel;
 using System.Security;
 using System.Text;
+using System.Text.RegularExpressions;
 using Newtonsoft.Json;
 
 namespace GitHub.DistributedTask.Logging
@@ -80,6 +81,65 @@ namespace GitHub.DistributedTask.Logging
             return trimmed;
         }
 
+        public static String PowerShellPreAmpersandEscape(String value)
+        {
+            // if the secret is passed to PS as a command and it causes an error, sections of it can be surrounded by color codes
+            // or printed individually. 
+            
+            // The secret secretpart1&secretpart2&secretpart3 would be split into 2 sections:
+            // 'secretpart1&secretpart2&' and 'secretpart3'. This method masks for the first section.
+            
+            // The secret secretpart1&+secretpart2&secretpart3 would be split into 2 sections:
+            // 'secretpart1&+' and (no 's') 'ecretpart2&secretpart3'. This method masks for the first section.
+
+            var trimmed = string.Empty;
+            if (!string.IsNullOrEmpty(value) && value.Contains("&"))
+            {
+                var secretSection = string.Empty;
+                if (value.Contains("&+"))
+                {
+                    secretSection = value.Substring(0, value.IndexOf("&+") + "&+".Length);
+                }
+                else
+                {
+                    secretSection = value.Substring(0, value.LastIndexOf("&") + "&".Length);
+                }
+
+                // Don't mask short secrets
+                if (secretSection.Length >= 6)
+                {
+                    trimmed = secretSection;
+                }
+            }
+
+            return trimmed;
+        }
+
+        public static String PowerShellPostAmpersandEscape(String value)
+        {
+            var trimmed = string.Empty;
+            if (!string.IsNullOrEmpty(value) && value.Contains("&"))
+            {
+                var secretSection = string.Empty;
+                if (value.Contains("&+"))
+                {
+                    // +1 to skip the letter that got colored
+                    secretSection = value.Substring(value.IndexOf("&+") + "&+".Length + 1);
+                }
+                else
+                {
+                    secretSection = value.Substring(value.LastIndexOf("&") + "&".Length);
+                }
+
+                if (secretSection.Length >= 6)
+                {
+                    trimmed = secretSection;
+                }
+            }
+
+            return trimmed;
+        }
+
         private static string Base64StringEscapeShift(String value, int shift)
         {
             var bytes = Encoding.UTF8.GetBytes(value);

src/Test/L0/HostContextL0.cs

@@ -112,6 +112,36 @@ namespace GitHub.Runner.Common.Tests
             }
         }
 
+        [Theory]
+        [InlineData("secret&secret&secret", "secret&secret&\x0033[96msecret\x0033[0m", "***\x0033[96m***\x0033[0m")]
+        [InlineData("secret&secret+secret", "secret&\x0033[96msecret+secret\x0033[0m", "***\x0033[96m***\x0033[0m")]
+        [InlineData("secret+secret&secret", "secret+secret&\x0033[96msecret\x0033[0m", "***\x0033[96m***\x0033[0m")]
+        [InlineData("secret&secret&+secretsecret", "secret&secret&+\x0033[96ms\x0033[0mecretsecret", "***\x0033[96ms\x0033[0m***")]
+        [InlineData("secret&+secret&secret", "secret&+\x0033[96ms\x0033[0mecret&secret", "***\x0033[96ms\x0033[0m***")]
+        [InlineData("secret&+secret&+secret", "secret&+\x0033[96ms\x0033[0mecret&+secret", "***\x0033[96ms\x0033[0m***")]
+        [InlineData("secret&+secret&secret&+secret", "secret&+\x0033[96ms\x0033[0mecret&secret&+secret", "***\x0033[96ms\x0033[0m***")]
+        [Trait("Level", "L0")]
+        [Trait("Category", "Common")]
+        public void SecretSectionMasking(string secret, string rawOutput, string maskedOutput)
+        {
+            try
+            {
+                // Arrange.
+                Setup();
+
+                // Act.
+                _hc.SecretMasker.AddValue(secret);
+
+                // Assert.
+                Assert.Equal(maskedOutput, _hc.SecretMasker.MaskSecrets(rawOutput));
+            }
+            finally
+            {
+                // Cleanup.
+                Teardown();
+            }
+        }
+
         [Fact]
         [Trait("Level", "L0")]
         [Trait("Category", "Common")]