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Magic crib now only applies after all branches have been explored.

This commit is contained in:
n1474335 2018-12-19 17:24:38 +00:00
parent 6337e84708
commit ed2c886359
2 changed files with 24 additions and 21 deletions
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33
src/core/lib/Magic.mjs
View File

@ -265,10 +265,10 @@ class Magic {
* performance)
* @param {Object[]} [recipeConfig=[]] - The recipe configuration up to this point
* @param {boolean} [useful=false] - Whether the current recipe should be scored highly
* @param {string} [filter=null] - The regex crib provided by the user, to filter the operation output
* @param {string} [crib=null] - The regex crib provided by the user, for filtering the operation output
* @returns {Object[]} - A sorted list of the recipes most likely to result in correct decoding
*/
async speculativeExecution(depth=0, extLang=false, intensive=false, recipeConfig=[], useful=false, filter=null) {
async speculativeExecution(depth=0, extLang=false, intensive=false, recipeConfig=[], useful=false, crib=null) {
if (depth < 0) return [];
// Find any operations that can be run on this data
@ -277,20 +277,17 @@ class Magic {
let results = [];
// Record the properties of the current data
// Only if there either wasn't a filter provided,
// or the filter matches in the data
if (filter == null || new RegExp(filter).test(this.inputStr)){
results.push({
recipe: recipeConfig,
data: this.inputStr.slice(0, 100),
languageScores: this.detectLanguage(extLang),
fileType: this.detectFileType(),
isUTF8: this.isUTF8(),
entropy: this.calcEntropy(),
matchingOps: matchingOps,
useful: useful
});
}
results.push({
recipe: recipeConfig,
data: this.inputStr.slice(0, 100),
languageScores: this.detectLanguage(extLang),
fileType: this.detectFileType(),
isUTF8: this.isUTF8(),
entropy: this.calcEntropy(),
matchingOps: matchingOps,
useful: useful,
matchesCrib: crib && crib.test(this.inputStr)
});
const prevOp = recipeConfig[recipeConfig.length - 1];
// Execute each of the matching operations, then recursively call the speculativeExecution()
@ -309,7 +306,7 @@ class Magic {
const magic = new Magic(output, this.opPatterns),
speculativeResults = await magic.speculativeExecution(
depth-1, extLang, intensive, [...recipeConfig, opConfig], op.useful, filter);
depth-1, extLang, intensive, [...recipeConfig, opConfig], op.useful, crib);
results = results.concat(speculativeResults);
}));
@ -321,7 +318,7 @@ class Magic {
await Promise.all(bfEncodings.map(async enc => {
const magic = new Magic(enc.data, this.opPatterns),
bfResults = await magic.speculativeExecution(
depth-1, extLang, false, [...recipeConfig, enc.conf], useful, filter);
depth-1, extLang, false, [...recipeConfig, enc.conf], false, crib);
results = results.concat(bfResults);
}));

12
src/core/operations/Magic.mjs
View File

@ -23,7 +23,7 @@ class Magic extends Operation {
this.name = "Magic";
this.flowControl = true;
this.module = "Default";
this.description = "The Magic operation attempts to detect various properties of the input data and suggests which operations could help to make more sense of it.<br><br><b>Options</b><br><u>Depth:</u> If an operation appears to match the data, it will be run and the result will be analysed further. This argument controls the maximum number of levels of recursion.<br><br><u>Intensive mode:</u> When this is turned on, various operations like XOR, bit rotates, and character encodings are brute-forced to attempt to detect valid data underneath. To improve performance, only the first 100 bytes of the data is brute-forced.<br><br><u>Extensive language support:</u> At each stage, the relative byte frequencies of the data will be compared to average frequencies for a number of languages. The default set consists of ~40 of the most commonly used languages on the Internet. The extensive list consists of 284 languages and can result in many languages matching the data if their byte frequencies are similar.<br><br>Optionally enter a regular expression to match a string you expect to find to filter results (crib)";
this.description = "The Magic operation attempts to detect various properties of the input data and suggests which operations could help to make more sense of it.<br><br><b>Options</b><br><u>Depth:</u> If an operation appears to match the data, it will be run and the result will be analysed further. This argument controls the maximum number of levels of recursion.<br><br><u>Intensive mode:</u> When this is turned on, various operations like XOR, bit rotates, and character encodings are brute-forced to attempt to detect valid data underneath. To improve performance, only the first 100 bytes of the data is brute-forced.<br><br><u>Extensive language support:</u> At each stage, the relative byte frequencies of the data will be compared to average frequencies for a number of languages. The default set consists of ~40 of the most commonly used languages on the Internet. The extensive list consists of 284 languages and can result in many languages matching the data if their byte frequencies are similar.<br><br>Optionally enter a regular expression to match a string you expect to find to filter results (crib).";
this.infoURL = "https://github.com/gchq/CyberChef/wiki/Automatic-detection-of-encoded-data-using-CyberChef-Magic";
this.inputType = "ArrayBuffer";
this.outputType = "JSON";
@ -61,10 +61,16 @@ class Magic extends Operation {
*/
async run(state) {
const ings = state.opList[state.progress].ingValues,
[depth, intensive, extLang, filter] = ings,
[depth, intensive, extLang, crib] = ings,
dish = state.dish,
magic = new MagicLib(await dish.get(Dish.ARRAY_BUFFER)),
options = await magic.speculativeExecution(depth, extLang, intensive, [], false, filter);
cribRegex = (crib && crib.length) ? new RegExp(crib, "i") : null;
let options = await magic.speculativeExecution(depth, extLang, intensive, [], false, cribRegex);
// Filter down to results which matched the crib
if (cribRegex) {
options = options.filter(option => option.matchesCrib);
}
// Record the current state for use when presenting
this.state = state;