Monday, December 16, 2019

Node Package Manager (NPM) Client hacked

NPM (originally short for Node Package Manager) is a package manager for the JavaScript programming language. It is the default package manager for the JavaScript runtime environment Node.js. It consists of a command line client, also called npm, and an online database of public and paid-for private packages, called the npm registry. 

Npm (Node.js Package Manager) devs say the npm command-line interface (CLI) client is impacted by a security bug -- a combination between a file traversal and an arbitrary file (over)write issue.

The bug can be exploited by attackers to plant malicious binaries or overwrite files on a user's computer. The vulnerability can be exploited only during the installation of a booby-trapped npm package via the npm CLI.

Source (Dec 11, 2019) : https://blog.npmjs.org/post/189618601100/binary-planting-with-the-npm-cli

Wednesday, December 11, 2019

CSharp : Convert a GUID to a Darwin Descriptor and back

Here's how to convert/decode a GUID into Darwin Descriptor in C-Sharp

Darwin Descriptor is an encoded string and when decoded produces a combination of the ProductCode, Feature & ComponentId(s) and generally used for Windows installer, because it provides feature resilience through a mechanism called COM Advertising.

Here's an example of a Darwin Descriptor, which you may have though was a virus entry in your registry!

"w_1^VX!!!!!!!!!MKKSkEXCELFiles>tW{~$4Q]c@II=l2xaTO5Z"

decoded yields a GUID, feature name, and a GUID.

{91120000-0030-0000-0000-0000000ff1ce}EXCELFiles{0638c49d-bb8b-4cd1-b191-052e8f325736}


Note: A "Compressed GUID" is a intermediate format, that rearranges the GUID and is Base85 encoded (using a restricted set) and has a length of 20 characters long and used to create Darwin Descriptors. 

Those cryptic-looking strings (that looks like malware) in your registry are actually Darwin Descriptors and can be located at the following locations; 

  • HKCR\Installer\Assemblies and HKCR\Installer\Components
  • HKCR\Installer\Win32Assemblies
  • HKLM\SOFTWARE\Microsoft\Windows\CurrentVersion\Installer\UserData\{aSID}\Products\{compressed}\Features{targetpath}











To decode Darwin Descriptors en masse, use RegtoText tool (free demo available). 

Here's the code to convert a regular GUID into Darwin Descriptor in C-Sharp and vice-versa

 
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using System;
//#####################################################################################################################
//https://metadataconsulting.blogspot.com/2019/12/CSharp-Convert-a-GUID-to-a-Darwin-Descriptor-and-back.html
//#####################################################################################################################
public static class Program
{
 class GUID2DD
    {
        //   Conversion of this VB code to C# by http://metadataconsulting.blogspot.com/
        //   Some portions modernized, but an interesting exercise converting from a old language unexpressive to more modern lang
        //   Source Code: https://www.symantec.com/connect/articles/working-darwin-descriptors
        //
        //   Auto VB translators 
        //   1.https://www.developerfusion.com/tools/convert/vb-to-csharp/?batchId=8e249124-06d2-4955-a238-dc2914a9cd3d - not good
        //   2.https://www.carlosag.net/tools/codetranslator/ - super fast!

        
        //  'VB Code - Copyright EdT 2012
        //  'Script converts standard GUID to Darwin Descriptor and vice versa
        //  'A standard GUID requires 38 characters and contains 5 groups of hexadecimal characters separated by dashes.
        //  'The valid format for a standard GUID is:
        //  '{XXXXXXXX-XXXX-XXXX-XXXX-XXXXXXXXXXXX}
        //  'where X is a hex digit (0,1,2,3,4,5,6,7,8,9,A,B,C,D,E,F).
        // 
        //  'This program can copy the result of the conversion process to the clipboard.
        //  'To do this it uses the MS Office Word automation object, so for this to work,
        //  'a version of MSOffice must be present. Unfortunately, VBScript does not have
        //  'a native method for copying variables to the clipboard.
      
        public string GetConvertedGUID(string strProductCode) {
            
            string Block1;
            string Block2;
            string Block3;
            string Block4;
            string strMungedCode = string.Empty; 
            long Dec1;
            long Dec2;
            long Dec3;
            long Dec4;
            string strPart1; 
            string strPart2; 
            string strPart3; 
            string strPart4; 
            
            const int intArraySize = 32;
            int[] arrSequence = new int[]{2, 3, 4, 5, 6, 7, 8, 9, 16, 17, 18, 19, 11, 12, 13, 14, 28, 29, 26, 27, 23, 24, 21, 22, 36, 37, 34, 35, 32, 33, 30, 31};
            
           // Generate the RegProduct Code
            for (int intIndex = 0; intIndex <= (intArraySize - 1); intIndex++) 
            {
                strMungedCode = (strMungedCode + strProductCode.Substring((arrSequence[intIndex] - 1), 1));
            }
        
            Block1 = strMungedCode.Substring(0, 8);
            Block2 = strMungedCode.Substring(8, 8);
            Block3 = strMungedCode.Substring(16, 8);
            Block4 = strMungedCode.Substring(24, 8);
            Dec1 = HextoDec(Block1);
            strPart1 = DecToBase85(Dec1);
            Dec2 = HextoDec(Block2);
            strPart2 = DecToBase85(Dec2);
            Dec3 = HextoDec(Block3);
            strPart3 = DecToBase85(Dec3);
            Dec4 = HextoDec(Block4);
            strPart4 = DecToBase85(Dec4);

            return (strPart1.ReverseString()
                        + (strPart2
                        + (strPart3 + strPart4.ReverseString())));
        }

        public long HextoDec(string strHex)
        {
 
            //string strDigit;
            //int intDigit;
            //int intValue;
            
            long lngResult = 0;

            ////for (int intIndex = strHex.Length; (intIndex <= 1); intIndex = (intIndex + -1)) 
            //for (int intIndex = strHex.Length; intIndex >= 1; intIndex--)
            //{
               
            //    strDigit = strHex.Substring((intIndex - 1), 1);
                
            //    intDigit = (("0123456789ABCDEF".IndexOf(strDigit.ToUpper()) + 1) - 1);
                
            //    if ((intDigit >= 0)) {
                    
            //        //intValue = (intDigit * (16 | (strHex.Length - intIndex)));
            //        // TODO: Warning!!! The operator should be an XOR ^ instead of an OR, but not available in CodeDOM

            //        //Mon 09-Dec-19 6:54pm metadataconsulting.ca - XOR used
            //        intValue = (intDigit * (16 ^ (strHex.Length - intIndex)));
                    
            //        lngResult = (lngResult + intValue);
            //    }
            //    else {
                    
            //        lngResult = 0;
            //        intIndex = 0;
            //        //stop the loop
            //    }
            
            //}

            lngResult = Convert.ToInt64(strHex, 16); 
            return lngResult;
    
        }
        private string DecitoHex(int ddec)
        {
            //// Must return eight hex bytes
            //decimal hex1;
            //string hex2 = ""; 
            //int hexlen;

            //while ((strDec > 15)) {

            //    hex1 = (( (strDec / 16) - (int)(strDec / 16) ) * 16);

            //    hex2 = ("0123456789ABCDEF".Substring(hex1.ToString(), 1) + hex2);
            //    strDec = int((strDec / 16));

            //    hex2 = ("0123456789ABCDEF".Substring(strDec, 1) + hex2);
            //    hexlen = hex2.Length;
            //    DecToHex = (string((8 - hexlen), "0") + hex2);
            //}

            return ddec.ToString("X8");
        }

    
        public string DecToBase85(long strDecimal) {
     
            // Multiples of 85 = 85, 7225, 614125, 52200625
            
            int strDec = (int)strDecimal;

            string Base85 = "!$%&\'()*+,-.0123456789=?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_`abcdefghijklmnopqrstuvwxyz{}~";
            
            int num;
            string quint1;
            string quint2;
            string quint3;
            string quint4;
            string quint5;
            //int Offset;
            
            quint1 = "!";
            quint2 = "!";
            quint3 = "!";
            quint4 = "!";
            quint5 = "!";

            if ((strDecimal < 85))
            {
                //quint1 = Base85.Substring(strDec, 1);
                long mod = strDecimal % 85;
                num = (int)mod;
                quint1 = Base85.Substring(num, 1);
            }

            if (strDecimal > 84 && strDecimal < 7225)
            {
                //    Offset = strDec;
                //    strDec = (int)((strDec / 85));
                //    num = (((Offset / 85) 
                //                - strDec) 
                //                * 85);
                //    quint1 = Base85.Substring(num, 1);
                //    quint2 = Base85.Substring(strDec, 1);

                num = (int)(strDecimal / 85) % 85;
                quint1 = Base85.Substring(num, 1);

                long mod = strDecimal % 85;
                num = (int)mod;
                quint2 = Base85.Substring(num, 1);
                
            }

            if (((strDecimal > 7224) && (strDecimal < 614125)))
            {
                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);
                //quint1 = Base85.Substring(num, 1);
                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);
                //quint2 = Base85.Substring(num, 1);
                //quint3 = Base85.Substring(strDec, 1);

                num = (int)(strDecimal / 7225) % 85;
                quint1 = Base85.Substring(num, 1);

                num = (int)(strDecimal / 85) % 85;
                quint2 = Base85.Substring(num, 1);

                long mod = strDecimal % 85;
                num = (int)mod;
                quint3 = Base85.Substring(num, 1);

            }

            if (((strDecimal > 614124) && (strDecimal < 52200625)))
            {
                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);
                //quint1 = Base85.Substring(num, 1);

                num = (int)(strDecimal / 614125) % 85;
                quint1 = Base85.Substring(num, 1);
                
                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);
                //quint2 = Base85.Substring(num, 1);

                num = (int)(strDecimal / 7225) % 85;
                quint2 = Base85.Substring(num, 1);
              
                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);
                //quint3 = Base85.Substring(num, 1);
                //quint4 = Base85.Substring(strDec, 1);

                num = (int)(strDecimal / 85) % 85;
                quint3 = Base85.Substring(num, 1);

                long mod = strDecimal % 85;
                num = (int)mod;
                quint4 = Base85.Substring(num, 1);
            }

            if ((strDecimal > 52200624))
            {
                
                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);
                                
                num = (int)(strDecimal/52200625) % 85; 
                quint1 = Base85.Substring(num, 1);

                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);

                num = (int)(strDecimal / 614125) % 85; 
                quint2 = Base85.Substring(num, 1);
                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);

                num = (int)(strDecimal / 7225) % 85;
                quint3 = Base85.Substring(num, 1);
                //Offset = strDec;
                //strDec = (int)((strDec / 85));
                //num = (((Offset / 85) 
                //            - strDec) 
                //            * 85);
                num = (int)(strDecimal / 85) % 85;
                quint4 = Base85.Substring(num, 1);

                long mod = strDecimal % 85;
                num = (int)mod; 
                quint5 = Base85.Substring(num, 1);
            }
        
            return (quint1 
                        + (quint2 
                        + (quint3 
                        + (quint4 + quint5))));
            
        }



        
        //Function DDtoHex(darwin) renamed from VB
        public string DDtoGUID(string darwin) {
            string quad1;
            string quad2;
            string quad3;
            string quad4;
            string mungedStr;
            quad1 = darwin.Substring(0, 5);
            quad1 = QuadtoHex(quad1);
            quad2 = darwin.Substring(5, 5);
            quad2 = QuadtoHex(quad2);
            quad3 = darwin.Substring(10, 5);
            quad3 = QuadtoHex(quad3);
            quad4 = darwin.Substring(15, 5);
            quad4 = QuadtoHex(quad4);
            mungedStr = (quad1 
                        + (quad2 
                        + (quad3 + quad4)));
            return ReconstructProductCode(mungedStr);
        }
    
        public string QuadtoHex(string quad) {
            
            char chr;
            string Base85;
            int b85;
            int ddec;
            Base85 = "!$%&\'()*+,-.0123456789=?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[]^_`abcdefghijklmnopqrstuvwxyz{}~";
            ddec = 0;
            for (int i = 5; i >= 1; i--)
            {
                //chr = (char)quad.Substring((i - 1), 1);
                chr = quad[(i-1)];  
                b85 = ((Base85.IndexOf(chr) + 1) - 1);
                ddec = (ddec + b85);
                if ((i > 1)) {
                    ddec = (ddec * 85);
                }
            
            }

            return DecitoHex(ddec);
        }


    
        public string ReconstructProductCode(string munged) {
            
            string strProductCode;
            const int intArraySize = 32;
            strProductCode = "{";
            
            int[] arrSequence = new int[]{1, 2, 3, 4, 5, 6, 7, 8, 13, 14, 15, 16, 9, 10, 11, 12, 23, 24, 21, 22, 19, 20, 17, 18, 31, 32, 29, 30, 27, 28, 25, 26};
            // // Generate the Product Code
            for (int intIndex = 0; (intIndex 
                        <= (intArraySize - 1)); intIndex++) {
                strProductCode = (strProductCode + munged.Substring((arrSequence[intIndex] - 1), 1));
                if (((intIndex == 7) 
                            || ((intIndex == 11) 
                            || ((intIndex == 15) 
                            || (intIndex == 19))))) {
                    strProductCode = (strProductCode + "-");
                }
            
            }
        
            return (strProductCode + "}");
        }
    }
 
 public static string ReverseString(this string s)
 {
  if (string.IsNullOrEmpty(s))
   return s; 

  char[] array = new char[s.Length];
  int forward = 0;
  for (int i = s.Length - 1; i >= 0; i--)
  {
   array[forward++] = s[i];
  }
  return new string(array);
 }

 
 public static void Main()
 {
   GUID2DD conv = new GUID2DD();

  string code = "w_1^VX!!!!!!!!!MKKSk"; 
  //string code = "{91120000-0030-0000-0000-0000000ff1ce}"; //expect from above
  string result = string.Empty;

  // check if this is a GUID
  if ((code.Length == 38))
  {

   if ((code.Substring(0, 1) == "{"))
    result = conv.GetConvertedGUID(code);

  }
  else if ((code.Length == 20))
  {

   result = conv.DDtoGUID(code);
  }
  else
  {

   result = "Format of string submitted does not match that of a regular GUID or a Darwin Descriptor. Entries must" +
    " be of the form {xxxxxxxx-xxxx-xxxx-xxxx-Xxxxxxxxxxxx} or xxxxxxxxxxxxxxxxxxxx (len=20)";
  }

  Console.WriteLine(code+"  => " + result);

 }
}