39 lines
1.9 KiB
JavaScript
39 lines
1.9 KiB
JavaScript
// Bounded decoding for common wire encodings. This is not arbitrary deobfuscation.
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export function inspectionTextVariants(text,maxBytes){
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const values=[],seen=new Set();let size=0,candidates=0;
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const budget=Math.min(maxBytes*4,16*1024*1024);
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function add(value,depth){
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if(typeof value!=='string'||seen.has(value))return;
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if(depth>3)throw Error('Inspection normalization limit');
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const bytes=Buffer.byteLength(value);
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if(values.length>=64||bytes>maxBytes||size+bytes>budget)throw Error('Inspection normalization limit');
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if(value.includes('\0'))return;
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seen.add(value);size+=bytes;values.push({value,depth});
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}
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add(text,0);
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for(let i=0;i<values.length;i++){
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const {value,depth}=values[i];
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try{add(decodeURIComponent(value.replace(/\+/g,' ')),depth+1);}catch(error){if(error.message==='Inspection normalization limit')throw error;}
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try{const parsed=JSON.parse(value);const queue=[parsed];let nodes=0;
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while(queue.length){if(++nodes>4096)throw Error('Inspection normalization limit');const node=queue.pop();
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if(typeof node==='string')add(node,depth+1);
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else if(node&&typeof node==='object'){
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const children=Object.values(node);
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if(nodes+queue.length+children.length>4096)throw Error('Inspection normalization limit');
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for(const child of children)queue.push(child);
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}
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}
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}catch(error){if(error.message==='Inspection normalization limit')throw error;}
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for(const match of value.matchAll(/[A-Za-z0-9+/_-]{12,}={0,2}/g)){
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const encoded=match[0].replace(/-/g,'+').replace(/_/g,'/'),raw=Buffer.from(encoded,'base64');
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if(raw.toString('base64').replace(/=+$/,'')!==encoded.replace(/=+$/,''))continue;
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try{const decoded=new TextDecoder('utf-8',{fatal:true}).decode(raw);
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if(decoded.includes('\0'))continue;
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if(++candidates>256)throw Error('Inspection normalization limit');
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add(decoded,depth+1);
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}catch(error){if(error.message==='Inspection normalization limit')throw error;}
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}
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}
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return values.map(row=>row.value);
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}
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