How can I parse CDATA?

How can I find and iterate through all the nodes present under CDATA and those nodes are started by (<) and closed by (>)?

Also, how should I iterate over all the child nodes and get the values like in below child node? I want to retrieve the value.

Input XML

    <SOURCE TransactionId="1" ProviderName="ABCDD"><RESPONSE><![CDATA[<?xml version="1.0" encoding="utf-8"?><soap:Envelope xmlns:soap="http://www.w3.org/2003/05/soap-envelope" xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance" xmlns:xsd="http://www.w3.org/2001/XMLSchema"><soap:Body><NetworkResponse xmlns="http://www.example.com/"><NetworkResult>&lt;Network offering_id="13" transaction_id="2" submission_id="3" timestamp="20140828  16010683 GMT" customer_id="NETTest"&gt;
        &lt;Network_List&gt;
            &lt;Network_Info att0="Y" att1="N" att2="N" att3="Y" att4="Y"&gt;
            &lt;SIM_DATA&gt;
                    &lt;SIM&gt;&lt;![CDATA[1100040101]]&gt;&lt;/SIM&gt;
    &lt;/SIM_DATA&gt;
    &lt;NetworkResponseInfo k_status="C"&gt;
                    &lt;KEY1&gt;269&lt;/KEY1&gt;
                    &lt;PARENTNODE&gt;
                        &lt;CHILDNODE1&gt;
                            &lt;KEY2&gt;XXXXXXX&lt;/KEY2&gt;
                            &lt;KEY3&gt;YYYYYYY&lt;/KEY3&gt;
                        &lt;/CHILDNODE1&gt;
                        &lt;CHILDNODE2&gt;
                            &lt;KEY4&gt;N&lt;/KEY4&gt;
                            &lt;KEY5&gt;I&lt;/KEY5&gt;
                        &lt;/CHILDNODE2&gt;
                        &lt;CHILDNODE3&gt;
                            &lt;KEY6&gt;1&lt;/KEY6&gt;
                            &lt;KEY7&gt;3&lt;/KEY7&gt;
                        &lt;/CHILDNODE3&gt;
                    &lt;/PARENTNODE&gt;
                        &lt;KEY8&gt;&lt;![CDATA[some image not visible]]&gt;&lt;/KEY8&gt;
                        &lt;KEY9&gt;N&lt;/KEY9&gt;
                        &lt;KEY10&gt;15&lt;/KEY10&gt;
                &lt;/NetworkResponseInfo&gt;
            &lt;/Network_Info&gt;
        &lt;/Network_List&gt;
        &lt;response_message_list transaction_status_code="000" transaction_status_text="Successful"/&gt;
    &lt;/Network&gt;</NetworkResult></NetworkResponse></soap:Body></soap:Envelope>]]></RESPONSE></SOURCE>

Output XML

                <ns3:NetworkResponse>
                            <Networks_OF_List>
                                <NetCharSeq>
                                    <Nrep>
                                        <type>Some Image</type>
                                        <data>  Data Coming from KEY8 CDATA section</data>
                                    </Nrep>
                                    <Nrep>
                                        <type>ANYTHING</type>
                                        <data>VALUE INSIDE SIM CDATA</data>
                                    </Nrep>
                                    <NetDetail>
                                        <MYKEY1>Value present inside KEY4</MYKEY1>
                                        <MYKEY2>Value present inside KEY5</MYKEY2>
                                    </NetDetail>
                                    <SystemID>Value of KEY2</SystemID>
                                    <SystemPath>Valuelue of KEY3</SystemPath>
                                </NetCharSeq>
                            </Networks_OF_List>
                        </ns3:NetworkResponse>

(Welcome at SO. Please note that you are downvoted by some users because you do not show what you have done so far. Have a look at the How To Ask section to learn how to ask questions that actually can be answered and are considered proper questions in the SO format.)

If you can use XSLT 3.0, you can consider using the new fn:parse-xml function, which will take a document-as-a-string.

However, your CDATA-section contains itself escaped data, which means that, after you apply fn:parse-xml, you will have to do it once again for the text node that is the child of NetworkResult.

A better solution is often to fix this at the source and creating an XML format that allows other XML in certain elements (you can allow this with a proper XSD). It will save you a lot of trouble and at least you XML can then be pre-validated.

If you are stuck with XSLT 2.0 or 1.0, you can use disable-output-escaping (google it, there is a lot of info around on how to use it), but you will have to re-process your output once more because of the double-escape that is used. You may want to consider an XProc pipeline to ease the process.

You wrote: Also, how should I iterate over all the child nodes and get the values like in below child node

That is what XSLT is all about, please read this XSLT Tutorial, or any other tutorial you can find, it will be explained to you in the first minutes.

Update: as suggested by michael.hor257k in the comments, you can also parse the escaped data by hand using string manipulation functions. As he already says in the comments, this is laborious and error-prone, but sometimes, esp. if the XML is not really XML after unescaping, but something like XML, then this may be your only option.