Detect presence of private IP addresses in URLs (ASIM Web Session)

Original query, unchanged.

let lookback = 1h;
// Identified base64 encoded IPv4 addresses
let ipv4_encoded_identification_regex = @"\=([a-zA-Z0-9\/\+]*(?:(?:MC|Au|wL|MS|Eu|xL|Mi|Iu|yL|My|Mu|zL|NC|Qu|0L|NS|Uu|1L|Ni|Yu|2L|Ny|cu|3L|OC|gu|4L|OS|ku|5L){1}[a-zA-Z0-9\/\+]{2,4}){3}[a-zA-Z0-9\/\+\=]*)";
// Extractes IPv4 addresses as hex values
let ipv4_decoded_hex_extract = @"((?:(?:61|62|63|64|65|66|67|68|69|6a|6b|6c|6d|6e|6f|70|71|72|73|74|75|76|77|78|79|7a|41|42|43|44|45|46|47|48|49|4a|4b|4c|4d|4e|4f|50|51|52|53|54|55|56|57|58|59|5a|2f|2b|3d),){6,14}(?:61|62|63|64|65|66|67|68|69|6a|6b|6c|6d|6e|6f|70|71|72|73|74|75|76|77|78|79|7a|41|42|43|44|45|46|47|48|49|4a|4b|4c|4d|4e|4f|50|51|52|53|54|55|56|57|58|59|5a|2f|2b|3d))";
let ipV4_Private_FromPlainString = _Im_WebSession(starttime=ago(lookback), eventresult='Success')
    | where isnotempty(Url)
    | extend ip_inURL = extract(@"\b\d{1,3}\.\d{1,3}\.\d{1,3}\.\d{1,3}\b", 0, Url)
    | where ipv4_is_private(ip_inURL)
    | where not(ipv4_is_private(DstIpAddr)) // only take traffic going to internet
    | summarize
        EventCount=count(),
        EventEndTime = max(TimeGenerated),
        EventStartTime = min(TimeGenerated),
        Urls=tostring(make_set(Url, 100))
        by SrcIpAddr, SrcUsername, SrcHostname, ip_inURL;
let ipV4_Private_FromEncodedString = 
    _Im_WebSession(starttime=ago(lookback), eventresult='Success')
    | where isnotempty(Url)
    // Identify requests with encoded IPv4 addresses
    | where Url matches regex ipv4_encoded_identification_regex
    | where not(ipv4_is_private(DstIpAddr)) // only take traffic going to internet
    | project TimeGenerated, Url, SrcIpAddr, SrcUsername, SrcHostname
    // Extract IP candidates in their base64 encoded format, significantly reducing the dataset
    | extend extracted_encoded_ip_inURL = extract_all(ipv4_encoded_identification_regex, Url)
    // We could have more than one ip, expand them out
    | mv-expand extracted_encoded_ip_inURL to typeof(string)
    | summarize
        EventStartTime=min(TimeGenerated),
        EventEndTime=max(TimeGenerated),
        make_set(Url, 100),
        EventCount=count()
        by extracted_encoded_ip_inURL, SrcIpAddr, SrcUsername, SrcHostname
    // Pad if we need to
    | extend extracted_encoded_ip_inURL = iff(strlen(extracted_encoded_ip_inURL) % 2 == 0, extracted_encoded_ip_inURL, strcat(extracted_encoded_ip_inURL, "="))
    // Now decode the candidate to a long array, we cannot go straight to string as it cannot handle non-UTF8, we need to strip that first
    | extend extracted_encoded_ip_inURL = tostring(base64_decode_toarray(extracted_encoded_ip_inURL))
    // Extract the IP candidates from the array
    | extend hex_extracted = extract_all(ipv4_decoded_hex_extract, extracted_encoded_ip_inURL)
    // Expand, it's still possible that we might have more than 1 IP
    | mv-expand hex_extracted
    // Now we should have a clean string. We need to put it back into a dynamic array to convert back to a string.
    | extend hex_extracted = trim_end(",", tostring(hex_extracted))
    | extend hex_extracted = strcat("[", hex_extracted, "]")
    | extend hex_extracted = todynamic(hex_extracted)
    // Convert the array back into a string
    | extend decoded_ip_inURL = unicode_codepoints_to_string(hex_extracted)
    | where ipv4_is_private(decoded_ip_inURL)
    | project
        ip_inURL=decoded_ip_inURL,
        Urls=tostring(set_Url),
        EventStartTime,
        EventEndTime,
        EventCount,
        SrcIpAddr,
        SrcUsername,
        SrcHostname;
union ipV4_Private_FromPlainString, ipV4_Private_FromEncodedString
| extend Name = iif(SrcUsername contains "@", tostring(split(SrcUsername,'@',0)[0]),SrcUsername), UPNSuffix = iif(SrcUsername contains "@",tostring(split(SrcUsername,'@',1)[0]),"")