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Porcupiney Hairs
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Go: Add query to detect DSN Injection.
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‎go/ql/src/experimental/CWE-134/DsnBad.go

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func bad() interface{} {
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name := os.Args[1:]
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// This is bad. `name` can be something like `test?allowAllFiles=true&` which will allow an attacker to access local files.
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dbDSN := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8", "username", "password", "127.0.0.1", 3306, name)
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db, _ := sql.Open("mysql", dbDSN)
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return db
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}

‎go/ql/src/experimental/CWE-134/DsnGood.go

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func good() (interface{}, error) {
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name := os.Args[1]
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hasBadChar, _ := regexp.MatchString(".*[?].*", name)
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if hasBadChar {
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return nil, errors.New("Bad input")
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}
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dbDSN := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8", "username", "password", "127.0.0.1", 3306, name)
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db, _ := sql.Open("mysql", dbDSN)
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return db, nil
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}

‎go/ql/src/experimental/CWE-134/DsnInjection.qhelp

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<!DOCTYPE qhelp PUBLIC "-//Semmle//qhelp//EN" "qhelp.dtd">
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<qhelp>
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<overview>
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<p>If a Data-Source Name (DSN) is built using untrusted user input without proper sanitization,
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the system may be vulnerable to DSN injection vulnerabilities.</p>
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</overview>
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<recommendation>
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<p>If user input must be included in a DSN, additional steps should be taken to sanitize
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untrusted data, such as checking for special characters included in user input.</p>
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</recommendation>
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<example>
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<p>In the following examples, the code accepts the db name from the user,
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which it then uses to build a DSN string.</p>
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<p>The following example uses the unsanitized user input directly
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in the process of constructing a DSN name.
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A malicious user could provide special characters to change the meaning of this string, and
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carry out unexpected database operations.</p>
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<sample src="DsnBad.go" />
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<p>In the following example, the input provided by the user is sanitized before it is included
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in the DSN string.
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This ensures the meaning of the DSN string cannot be changed by a malicious user.</p>
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<sample src="DsnGood.go" />
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</example>
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<references>
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<li>
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CVE-2022-3023: <a href="https://nvd.nist.gov/vuln/detail/CVE-2022-3023/">Data Source Name Injection in pingcap/tidb.</a>
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</li>
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</references>
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</qhelp>

‎go/ql/src/experimental/CWE-134/DsnInjection.ql

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/**
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* @name SQL Data-source URI built from user-controlled sources
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* @description Building an SQL data-source URI from untrusted sources can allow attacker to compromise security
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* @kind path-problem
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* @problem.severity error
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* @id go/dsn-injection
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* @tags security
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* experimental
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* external/cwe/cwe-134
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*/
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import go
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import DataFlow::PathGraph
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import DsnInjectionCustomizations
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/** An untrusted flow source taken as a source for the `DsnInjection` taint-flow configuration. */
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private class UntrustedFlowAsSource extends Source instanceof UntrustedFlowSource { }
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from DsnInjection cfg, DataFlow::PathNode source, DataFlow::PathNode sink
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where cfg.hasFlowPath(source, sink)
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select sink.getNode(), source, sink, "This query depends on a $@.", source.getNode(),
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"user-provided value"

‎go/ql/src/experimental/CWE-134/DsnInjectionCustomizations.qll

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/** Provides a taint-tracking model to reason about Data-Source name injection vulnerabilities. */
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import go
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import DataFlow::PathGraph
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import semmle.go.dataflow.barrierguardutil.RegexpCheck
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/** A source for `DsnInjection` taint-flow configuration. */
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abstract class Source extends DataFlow::Node { }
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/** A taint-tracking configuration to reason about Data Source Name injection vulnerabilities. */
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class DsnInjection extends TaintTracking::Configuration {
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DsnInjection() { this = "DsnInjection" }
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override predicate isSource(DataFlow::Node node) { node instanceof Source }
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override predicate isSink(DataFlow::Node node) {
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exists(Function f | f.hasQualifiedName("database/sql", "Open") |
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node = f.getACall().getArgument(1)
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)
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}
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override predicate isSanitizer(DataFlow::Node node) { node instanceof RegexpCheckBarrier }
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}
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/** A model of a function which decodes or unmarshals a tainted input, propagating taint from any argument to either the method receiver or return value. */
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private class DecodeFunctionModel extends TaintTracking::FunctionModel {
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DecodeFunctionModel() {
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// This matches any function with a name like `Decode`,`Unmarshal` or `Parse`.
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// This is done to allow taints stored in encoded forms, such as in toml or json to flow freely.
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this.getName().matches("(?i).*(parse|decode|unmarshal).*")
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}
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override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
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input.isParameter(_) and
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(output.isResult(0) or output.isReceiver())
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}
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}
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/** A model of `flag.Parse`, propagating tainted input passed via CLI flags to `Parse`'s result. */
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private class FlagSetFunctionModel extends TaintTracking::FunctionModel {
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FunctionInput inp;
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FunctionOutput outp;
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FlagSetFunctionModel() { this.hasQualifiedName("flag", "Parse") }
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override predicate hasTaintFlow(FunctionInput input, FunctionOutput output) {
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input.isParameter(0) and output.isResult()
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}
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}

‎go/ql/src/experimental/CWE-134/DsnInjectionLocal.ql

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/**
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* @name SQL Data-source URI built from local user-controlled sources
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* @description Building an SQL data-source URI from untrusted sources can allow attacker to compromise security
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* @kind path-problem
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* @problem.severity error
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* @id go/dsn-injection
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* @tags security
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* experimental
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* external/cwe/cwe-134
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*/
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import go
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import DataFlow::PathGraph
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import DsnInjectionCustomizations
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/** An argument passed via the command line taken as a source for the `DsnInjection` taint-flow configuration. */
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private class OsArgsSource extends Source {
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OsArgsSource() { this = any(Variable c | c.hasQualifiedName("os", "Args")).getARead() }
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}
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from DsnInjection cfg, DataFlow::PathNode source, DataFlow::PathNode sink
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where cfg.hasFlowPath(source, sink)
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select sink.getNode(), source, sink, "This query depends on a $@.", source.getNode(),
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"user-provided value"

‎go/ql/test/experimental/CWE-134/Dsn.go

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package main
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import (
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"database/sql"
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"errors"
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"fmt"
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"net/http"
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"os"
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"regexp"
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)
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func good() (interface{}, error) {
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name := os.Args[1]
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hasBadChar, _ := regexp.MatchString(".*[?].*", name)
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if hasBadChar {
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return nil, errors.New("bad input")
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}
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dbDSN := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8", "username", "password", "127.0.0.1", 3306, name)
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db, _ := sql.Open("mysql", dbDSN)
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return db, nil
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}
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func bad() interface{} {
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name2 := os.Args[1:]
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// This is bad. `name` can be something like `test?allowAllFiles=true&` which will allow an attacker to access local files.
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dbDSN := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8", "username", "password", "127.0.0.1", 3306, name2[0])
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db, _ := sql.Open("mysql", dbDSN)
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return db
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}
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func good2(w http.ResponseWriter, req *http.Request) (interface{}, error) {
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name := req.FormValue("name")
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hasBadChar, _ := regexp.MatchString(".*[?].*", name)
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if hasBadChar {
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return nil, errors.New("bad input")
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}
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dbDSN := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8", "username", "password", "127.0.0.1", 3306, name)
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db, _ := sql.Open("mysql", dbDSN)
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return db, nil
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}
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func bad2(w http.ResponseWriter, req *http.Request) interface{} {
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name := req.FormValue("name")
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// This is bad. `name` can be something like `test?allowAllFiles=true&` which will allow an attacker to access local files.
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dbDSN := fmt.Sprintf("%s:%s@tcp(%s:%d)/%s?charset=utf8", "username", "password", "127.0.0.1", 3306, name)
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db, _ := sql.Open("mysql", dbDSN)
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return db
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}
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func main() {
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bad2(nil, nil)
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good()
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bad()
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good2(nil, nil)
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}

‎go/ql/test/experimental/CWE-134/DsnInjection.expected

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edges
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| Dsn.go:47:10:47:30 | call to FormValue | Dsn.go:50:29:50:33 | dbDSN |
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nodes
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| Dsn.go:47:10:47:30 | call to FormValue | semmle.label | call to FormValue |
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| Dsn.go:50:29:50:33 | dbDSN | semmle.label | dbDSN |
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subpaths
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#select
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| Dsn.go:50:29:50:33 | dbDSN | Dsn.go:47:10:47:30 | call to FormValue | Dsn.go:50:29:50:33 | dbDSN | This query depends on a $@. | Dsn.go:47:10:47:30 | call to FormValue | user-provided value |

‎go/ql/test/experimental/CWE-134/DsnInjection.qlref

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experimental/CWE-134/DsnInjection.ql

‎go/ql/test/experimental/CWE-134/DsnInjectionLocal.expected

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edges
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| Dsn.go:26:11:26:17 | selection of Args | Dsn.go:29:29:29:33 | dbDSN |
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nodes
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| Dsn.go:26:11:26:17 | selection of Args | semmle.label | selection of Args |
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| Dsn.go:29:29:29:33 | dbDSN | semmle.label | dbDSN |
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subpaths
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#select
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| Dsn.go:29:29:29:33 | dbDSN | Dsn.go:26:11:26:17 | selection of Args | Dsn.go:29:29:29:33 | dbDSN | This query depends on a $@. | Dsn.go:26:11:26:17 | selection of Args | user-provided value |

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