Question

I´m working on an application (developed with .NET Framework) that manages Android Application packages (apk) and the program has to read the ApplicationManifest.xml that resides inside the apk. Extracting the Manifest file from the apk is no problem, because I can use standard zip tools to extract all files from an apk.

But reading the ApplicationManifest is not possible. I expected that it contains raw XML data, but it’s somehow encrypted or encoded.

Is there a way using the BCL of the .NET Framework to read the XML data from the ApplicationManifest? Or is there a library for the .NET Framework to read the ApplicationManifest?

Answer 1

I would not recommend using the mentioned apktool, as it is not safe for automated decoding – I used to use it for the same reason as you did, but it failed in some cases.

There are some tools like axml2xml that are specialized in Android encoded XML files or other tools like Android Asset Packaging Tool (aapt). You can also code a decoder on your own.

axml2xml is not perfect, so I would recommend running aapt (included in Android SDK) on your apk, as it print a lot of information you can parse: aapt l -a <your.apk>

If you want to implement code to parse the Manifest yourself, have a look at ribo‘s community wiki entry:

// decompressXML -- Parse the 'compressed' binary form of Android XML docs 
// such as for AndroidManifest.xml in .apk files
public static int endDocTag = 0x00100101;
public static int startTag =  0x00100102;
public static int endTag =    0x00100103;
public void decompressXML(byte[] xml) {
// Compressed XML file/bytes starts with 24x bytes of data,
// 9 32 bit words in little endian order (LSB first):
//   0th word is 03 00 08 00
//   3rd word SEEMS TO BE:  Offset at then of StringTable
//   4th word is: Number of strings in string table
// WARNING: Sometime I indiscriminently display or refer to word in 
//   little endian storage format, or in integer format (ie MSB first).
int numbStrings = LEW(xml, 4*4);

// StringIndexTable starts at offset 24x, an array of 32 bit LE offsets
// of the length/string data in the StringTable.
int sitOff = 0x24;  // Offset of start of StringIndexTable

// StringTable, each string is represented with a 16 bit little endian 
// character count, followed by that number of 16 bit (LE) (Unicode) chars.
int stOff = sitOff + numbStrings*4;  // StringTable follows StrIndexTable

// XMLTags, The XML tag tree starts after some unknown content after the
// StringTable.  There is some unknown data after the StringTable, scan
// forward from this point to the flag for the start of an XML start tag.
int xmlTagOff = LEW(xml, 3*4);  // Start from the offset in the 3rd word.
// Scan forward until we find the bytes: 0x02011000(x00100102 in normal int)
for (int ii=xmlTagOff; ii<xml.length-4; ii+=4) {
  if (LEW(xml, ii) == startTag) { 
    xmlTagOff = ii;  break;
  }
} // end of hack, scanning for start of first start tag

// XML tags and attributes:
// Every XML start and end tag consists of 6 32 bit words:
//   0th word: 02011000 for startTag and 03011000 for endTag 
//   1st word: a flag?, like 38000000
//   2nd word: Line of where this tag appeared in the original source file
//   3rd word: FFFFFFFF ??
//   4th word: StringIndex of NameSpace name, or FFFFFFFF for default NS
//   5th word: StringIndex of Element Name
//   (Note: 01011000 in 0th word means end of XML document, endDocTag)

// Start tags (not end tags) contain 3 more words:
//   6th word: 14001400 meaning?? 
//   7th word: Number of Attributes that follow this tag(follow word 8th)
//   8th word: 00000000 meaning??

// Attributes consist of 5 words: 
//   0th word: StringIndex of Attribute Name's Namespace, or FFFFFFFF
//   1st word: StringIndex of Attribute Name
//   2nd word: StringIndex of Attribute Value, or FFFFFFF if ResourceId used
//   3rd word: Flags?
//   4th word: str ind of attr value again, or ResourceId of value

// TMP, dump string table to tr for debugging
//tr.addSelect("strings", null);
//for (int ii=0; ii<numbStrings; ii++) {
//  // Length of string starts at StringTable plus offset in StrIndTable
//  String str = compXmlString(xml, sitOff, stOff, ii);
//  tr.add(String.valueOf(ii), str);
//}
//tr.parent();

// Step through the XML tree element tags and attributes
int off = xmlTagOff;
int indent = 0;
int startTagLineNo = -2;
while (off < xml.length) {
  int tag0 = LEW(xml, off);
  //int tag1 = LEW(xml, off+1*4);
  int lineNo = LEW(xml, off+2*4);
  //int tag3 = LEW(xml, off+3*4);
  int nameNsSi = LEW(xml, off+4*4);
  int nameSi = LEW(xml, off+5*4);

  if (tag0 == startTag) { // XML START TAG
    int tag6 = LEW(xml, off+6*4);  // Expected to be 14001400
    int numbAttrs = LEW(xml, off+7*4);  // Number of Attributes to follow
    //int tag8 = LEW(xml, off+8*4);  // Expected to be 00000000
    off += 9*4;  // Skip over 6+3 words of startTag data
    String name = compXmlString(xml, sitOff, stOff, nameSi);
    //tr.addSelect(name, null);
    startTagLineNo = lineNo;

    // Look for the Attributes
    StringBuffer sb = new StringBuffer();
    for (int ii=0; ii<numbAttrs; ii++) {
      int attrNameNsSi = LEW(xml, off);  // AttrName Namespace Str Ind, or FFFFFFFF
      int attrNameSi = LEW(xml, off+1*4);  // AttrName String Index
      int attrValueSi = LEW(xml, off+2*4); // AttrValue Str Ind, or FFFFFFFF
      int attrFlags = LEW(xml, off+3*4);  
      int attrResId = LEW(xml, off+4*4);  // AttrValue ResourceId or dup AttrValue StrInd
      off += 5*4;  // Skip over the 5 words of an attribute

      String attrName = compXmlString(xml, sitOff, stOff, attrNameSi);
      String attrValue = attrValueSi!=-1
        ? compXmlString(xml, sitOff, stOff, attrValueSi)
        : "resourceID 0x"+Integer.toHexString(attrResId);
      sb.append(" "+attrName+"=\""+attrValue+"\"");
      //tr.add(attrName, attrValue);
    }
    prtIndent(indent, "<"+name+sb+">");
    indent++;

  } else if (tag0 == endTag) { // XML END TAG
    indent--;
    off += 6*4;  // Skip over 6 words of endTag data
    String name = compXmlString(xml, sitOff, stOff, nameSi);
    prtIndent(indent, "</"+name+">  (line "+startTagLineNo+"-"+lineNo+")");
    //tr.parent();  // Step back up the NobTree

  } else if (tag0 == endDocTag) {  // END OF XML DOC TAG
    break;

  } else {
    prt("  Unrecognized tag code '"+Integer.toHexString(tag0)
      +"' at offset "+off);
    break;
  }
} // end of while loop scanning tags and attributes of XML tree
prt("    end at offset "+off);
} // end of decompressXML


public String compXmlString(byte[] xml, int sitOff, int stOff, int strInd) {
  if (strInd < 0) return null;
  int strOff = stOff + LEW(xml, sitOff+strInd*4);
  return compXmlStringAt(xml, strOff);
}


public static String spaces = "                                             ";
public void prtIndent(int indent, String str) {
  prt(spaces.substring(0, Math.min(indent*2, spaces.length()))+str);
}


// compXmlStringAt -- Return the string stored in StringTable format at
// offset strOff.  This offset points to the 16 bit string length, which 
// is followed by that number of 16 bit (Unicode) chars.
public String compXmlStringAt(byte[] arr, int strOff) {
  int strLen = arr[strOff+1]<<8&0xff00 | arr[strOff]&0xff;
  byte[] chars = new byte[strLen];
  for (int ii=0; ii<strLen; ii++) {
    chars[ii] = arr[strOff+2+ii*2];
  }
  return new String(chars);  // Hack, just use 8 byte chars
} // end of compXmlStringAt


// LEW -- Return value of a Little Endian 32 bit word from the byte array
//   at offset off.
public int LEW(byte[] arr, int off) {
  return arr[off+3]<<24&0xff000000 | arr[off+2]<<16&0xff0000
    | arr[off+1]<<8&0xff00 | arr[off]&0xFF;
} // end of LEW

This method reads the AndroidManifest into a byte[] for processing:

public void getIntents(String path) {
  try {
    JarFile jf = new JarFile(path);
    InputStream is = jf.getInputStream(jf.getEntry("AndroidManifest.xml"));
    byte[] xml = new byte[is.available()];
    int br = is.read(xml);
    //Tree tr = TrunkFactory.newTree();
    decompressXML(xml);
    //prt("XML\n"+tr.list());
  } catch (Exception ex) {
    console.log("getIntents, ex: "+ex);  ex.printStackTrace();
  }
} // end of getIntents

In conclusion, I would recommend parsing the aapt output (you could bundle it with your application).