String pattern mitigation #930
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lu4p
reviewed
Mar 16, 2025
| @@ -59,6 +59,22 @@ func LambdaCall(resultType ast.Expr, block *ast.BlockStmt) *ast.CallExpr { | |||
| return CallExpr(funcLit) | |||
| } | |||
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| // LambdaCallParams "func(params) resultType {block}(args)" | |||
| func LambdaCallParams(params *ast.FieldList, resultType ast.Expr, block *ast.BlockStmt, args []ast.Expr) *ast.CallExpr { | |||
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Lambda call should just use this with nil params
internal/literals/obfuscators.go
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| type extKeyRarity int | ||
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| const ( | ||
| Rare extKeyRarity = 40 | ||
| Normal = 60 | ||
| Common = 80 | ||
| ) | ||
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| func (r extKeyRarity) Try(rand *mathrand.Rand) bool { | ||
| return rand.Intn(100) < int(r) | ||
| } | ||
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| type extKey struct { | ||
| name, typ string | ||
| value uint64 | ||
| bits int | ||
| refs int | ||
| } | ||
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| func (k *extKey) Byte() byte { | ||
| return byte(k.value) | ||
| } | ||
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| func (k *extKey) Type() *ast.Ident { | ||
| return ast.NewIdent(k.typ) | ||
| } | ||
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| func (k *extKey) Name() *ast.Ident { | ||
| return ast.NewIdent(k.name) | ||
| } | ||
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| func (k *extKey) AddRef() { | ||
| k.refs++ | ||
| } | ||
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| func (k *extKey) Used() bool { | ||
| return k.refs > 0 | ||
| } | ||
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internal/literals/obfuscators.go
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| return keys | ||
| } | ||
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| func addTrashExternalKeys(obfRand *mathrand.Rand, keys []*extKey) []*extKey { | ||
| if len(keys) >= maxExternalKeyCount { | ||
| return keys | ||
| } | ||
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| trashCount := maxExternalKeyCount - len(keys) | ||
| if trashCount > 1 { | ||
| trashCount = 1 + obfRand.Intn(trashCount) | ||
| } | ||
| for i := 0; i < trashCount; i++ { | ||
| keys = append(keys, randExternalKey(obfRand)) | ||
| } | ||
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| obfRand.Shuffle(len(keys), func(i, j int) { | ||
| keys[i], keys[j] = keys[j], keys[i] | ||
| }) | ||
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| return keys | ||
| } | ||
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| func externalKeysToParams(obfRand *mathrand.Rand, keys []*extKey) (params *ast.FieldList, args []ast.Expr) { | ||
| params = &ast.FieldList{} | ||
| for _, key := range addTrashExternalKeys(obfRand, keys) { | ||
| name := key.Name() | ||
| if !key.Used() { | ||
| name.Name = "_" | ||
| } | ||
| params.List = append(params.List, &ast.Field{ | ||
| Names: []*ast.Ident{name}, | ||
| Type: key.Type(), | ||
| }) | ||
| args = append(args, &ast.BasicLit{ | ||
| Kind: token.INT, | ||
| Value: fmt.Sprint(key.value), | ||
| }) | ||
| } | ||
| return | ||
| } | ||
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| func dataToByteSliceWithExternalKeys(obfRand *mathrand.Rand, data []byte, externalKeys []*extKey, rarity extKeyRarity) ast.Expr { | ||
| if !rarity.Try(obfRand) { | ||
| return ah.DataToByteSlice(data) | ||
| } | ||
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| count := len(data) / 2 | ||
| if count > maxExternalKeyCount*2 { | ||
| count = maxExternalKeyCount * 2 | ||
| } | ||
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| var stmts []ast.Stmt | ||
| for i := 0; i < count; i++ { | ||
| key := externalKeys[obfRand.Intn(len(externalKeys))] | ||
| key.AddRef() | ||
| idx, op, b := obfRand.Intn(len(data)), randOperator(obfRand), obfRand.Intn(key.bits/8) | ||
| data[idx] = evalOperator(op, data[idx], byte(key.value>>(b*8))) | ||
| stmts = append(stmts, &ast.AssignStmt{ | ||
| Lhs: []ast.Expr{ah.IndexExpr("data", ah.IntLit(idx))}, | ||
| Tok: token.ASSIGN, | ||
| Rhs: []ast.Expr{ | ||
| operatorToReversedBinaryExpr(op, | ||
| ah.IndexExpr("data", ah.IntLit(idx)), | ||
| ah.CallExprByName("byte", &ast.BinaryExpr{ | ||
| X: key.Name(), | ||
| Op: token.SHR, | ||
| Y: ah.IntLit(b * 8), | ||
| }), | ||
| ), | ||
| }, | ||
| }) | ||
| } | ||
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| slices.Reverse(stmts) | ||
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| stmts = append([]ast.Stmt{ah.AssignDefineStmt(ast.NewIdent("data"), ah.DataToByteSlice(data))}, append(stmts, ah.ReturnStmt(ast.NewIdent("data")))...) | ||
| return ah.LambdaCall(&ast.ArrayType{Elt: ast.NewIdent("byte")}, ah.BlockStmt(stmts...)) | ||
| } | ||
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| func byteLitWithExternalKeys(obfRand *mathrand.Rand, val byte, externalKeys []*extKey, rarity extKeyRarity) ast.Expr { | ||
| if !rarity.Try(obfRand) { | ||
| return ah.IntLit(int(val)) | ||
| } | ||
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| key := externalKeys[obfRand.Intn(len(externalKeyRanges))] | ||
| key.AddRef() | ||
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| op, b := randOperator(obfRand), obfRand.Intn(key.bits/8) | ||
| newVal := evalOperator(op, val, byte(key.value>>(b*8))) | ||
| return operatorToReversedBinaryExpr(op, | ||
| ah.CallExprByName("byte", ah.IntLit(int(newVal))), | ||
| ah.CallExprByName("byte", &ast.BinaryExpr{ | ||
| X: key.Name(), | ||
| Op: token.SHR, | ||
| Y: ah.IntLit(b * 8), | ||
| }), | ||
| ) | ||
| } | ||
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This needs more docs, whenever you generate code please add a comment with how the generated code looks like.
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WIP
Now implemented “external keys”, with random bit count (8/16/32/64). One key can be used many times and using bit shifting each key can be used differently
Roadmap:
string([]byte(""))pattern hiding (via proxy)Code examples
Closes #926