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Merge pull request #14075 from amammad/amammad-go-JWT
Go: Improved JWT query, JWT decoding without verification
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‎go/ql/src/experimental/CWE-321-V2/ExampleBad.go

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package main
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import (
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"fmt"
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"log"
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"github.com/go-jose/go-jose/v3/jwt"
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)
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var JwtKey = []byte("AllYourBase")
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func main() {
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// BAD: usage of a harcoded Key
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verifyJWT(JWTFromUser)
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}
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func LoadJwtKey(token *jwt.Token) (interface{}, error) {
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return JwtKey, nil
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}
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func verifyJWT(signedToken string) {
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fmt.Println("verifying JWT")
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DecodedToken, err := jwt.ParseWithClaims(signedToken, &CustomerInfo{}, LoadJwtKey)
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if claims, ok := DecodedToken.Claims.(*CustomerInfo); ok && DecodedToken.Valid {
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fmt.Printf("NAME:%v ,ID:%v\n", claims.Name, claims.ID)
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} else {
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log.Fatal(err)
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}
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}

‎go/ql/src/experimental/CWE-321-V2/HardCodedKeys.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>
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A JSON Web Token (JWT) is used for authenticating and managing users in an application.
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</p>
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<p>
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Using a hard-coded secret key for parsing JWT tokens in open source projects
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can leave the application using the token vulnerable to authentication bypasses.
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</p>
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<p>
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A JWT token is safe for enforcing authentication and access control as long as it can't be forged by a malicious actor. However, when a project exposes this secret publicly, these seemingly unforgeable tokens can now be easily forged.
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Since the authentication as well as access control is typically enforced through these JWT tokens, an attacker armed with the secret can create a valid authentication token for any user and may even gain access to other privileged parts of the application.
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</p>
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</overview>
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<recommendation>
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<p>
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Generating a cryptographically secure secret key during application initialization and using this generated key for future JWT parsing requests can prevent this vulnerability.
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</p>
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</recommendation>
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<example>
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<p>
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The following code uses a hard-coded string as a secret for parsing user provided JWTs. In this case, an attacker can very easily forge a token by using the hard-coded secret.
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</p>
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<sample src="ExampleBad.go" />
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</example>
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<references>
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<li>
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CVE-2022-0664:
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<a href="https://nvd.nist.gov/vuln/detail/CVE-2022-0664">Use of Hard-coded Cryptographic Key in Go github.com/gravitl/netmaker prior to 0.8.5,0.9.4,0.10.0,0.10.1. </a>
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</li>
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</references>
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</qhelp>

‎go/ql/src/experimental/CWE-321-V2/HardCodedKeys.ql

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/**
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* @name Decoding JWT with hardcoded key
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* @description Decoding JWT Secret with a Constant value lead to authentication or authorization bypass
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* @kind path-problem
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* @problem.severity error
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* @id go/parse-jwt-with-hardcoded-key
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* @tags security
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* experimental
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* external/cwe/cwe-321
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*/
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import go
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import experimental.frameworks.JWT
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module JwtParseWithConstantKeyConfig implements DataFlow::ConfigSig {
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predicate isSource(DataFlow::Node source) { source.asExpr() instanceof StringLit }
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predicate isSink(DataFlow::Node sink) {
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// first part is the JWT Parsing Functions that get a func type as an argument
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// Find a node that has flow to a key Function argument
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// then find the first result node of this Function which is the secret key
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exists(FuncDef fd, DataFlow::Node n, DataFlow::ResultNode rn |
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fd = n.asExpr()
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or
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n = fd.(FuncDecl).getFunction().getARead()
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|
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GolangJwtKeyFunc::flow(n, _) and
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sink = rn and
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rn.getRoot() = fd and
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rn.getIndex() = 0
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)
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or
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// second part is the JWT Parsing Functions that get a string or byte as an argument
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sink = any(JwtParse jp).getKeyArg()
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}
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}
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module GolangJwtKeyFuncConfig implements DataFlow::ConfigSig {
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predicate isSource(DataFlow::Node source) {
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source = any(Function f).getARead()
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or
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source.asExpr() = any(FuncDef fd)
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}
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predicate isSink(DataFlow::Node sink) {
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sink = any(JwtParseWithKeyFunction parseJwt).getKeyFuncArg()
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}
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}
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module JwtParseWithConstantKey = TaintTracking::Global<JwtParseWithConstantKeyConfig>;
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module GolangJwtKeyFunc = TaintTracking::Global<GolangJwtKeyFuncConfig>;
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import JwtParseWithConstantKey::PathGraph
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from JwtParseWithConstantKey::PathNode source, JwtParseWithConstantKey::PathNode sink
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where JwtParseWithConstantKey::flowPath(source, sink)
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select sink.getNode(), source, sink, "This $@.", source.getNode(),
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"Constant Key is used as JWT Secret key"

‎go/ql/src/experimental/CWE-347/Example.go

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package main
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import (
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"fmt"
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"log"
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"github.com/golang-jwt/jwt/v5"
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)
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func main() {
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// BAD: only decode jwt without verification
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notVerifyJWT(token)
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// GOOD: decode with verification or verify plus decode
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notVerifyJWT(token)
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VerifyJWT(token)
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}
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func notVerifyJWT(signedToken string) {
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fmt.Println("only decoding JWT")
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DecodedToken, _, err := jwt.NewParser().ParseUnverified(signedToken, &CustomerInfo{})
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if claims, ok := DecodedToken.Claims.(*CustomerInfo); ok {
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fmt.Printf("DecodedToken:%v\n", claims)
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} else {
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log.Fatal("error", err)
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}
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}
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func LoadJwtKey(token *jwt.Token) (interface{}, error) {
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return ARandomJwtKey, nil
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}
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func verifyJWT(signedToken string) {
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fmt.Println("verifying JWT")
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DecodedToken, err := jwt.ParseWithClaims(signedToken, &CustomerInfo{}, LoadJwtKey)
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if claims, ok := DecodedToken.Claims.(*CustomerInfo); ok && DecodedToken.Valid {
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fmt.Printf("NAME:%v ,ID:%v\n", claims.Name, claims.ID)
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} else {
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log.Fatal(err)
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}
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}

‎go/ql/src/experimental/CWE-347/ParseJWTWithoutVerification.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>
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A JSON Web Token (JWT) is used for authenticating and managing users in an application.
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</p>
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<p>
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Only Decoding JWTs without checking if they have a valid signature or not can lead to security vulnerabilities.
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</p>
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</overview>
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<recommendation>
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<p>
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Don't use methods that only decode JWT, Instead use methods that verify the signature of JWT.
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</p>
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</recommendation>
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<example>
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<p>
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In the following code you can see an Example from a popular Library.
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</p>
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<sample src="Example.go" />
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</example>
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<references>
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<li>
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<a href="https://github.com/argoproj/argo-cd/security/advisories/GHSA-q9hr-j4rf-8fjc">JWT audience claim is not verified</a>
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</li>
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</references>
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</qhelp>

‎go/ql/src/experimental/CWE-347/ParseJWTWithoutVerification.ql

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/**
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* @name Use of JWT Methods that only decode user provided Token
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* @description Using JWT methods without verification can cause to authorization or authentication bypass
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* @kind path-problem
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* @problem.severity error
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* @id go/parse-jwt-without-verification
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* @tags security
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* experimental
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* external/cwe/cwe-321
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*/
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import go
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import experimental.frameworks.JWT
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module WithValidationConfig implements DataFlow::ConfigSig {
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predicate isSource(DataFlow::Node source) { source instanceof UntrustedFlowSource }
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predicate isSink(DataFlow::Node sink) {
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sink = any(JwtParse jwtParse).getTokenArg() or
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sink = any(JwtParseWithKeyFunction jwtParseWithKeyFunction).getTokenArg()
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}
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predicate isAdditionalFlowStep(DataFlow::Node nodeFrom, DataFlow::Node nodeTo) {
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golangJwtIsAdditionalFlowStep(nodeFrom, nodeTo)
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or
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goJoseIsAdditionalFlowStep(nodeFrom, nodeTo)
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}
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}
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module NoValidationConfig implements DataFlow::ConfigSig {
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predicate isSource(DataFlow::Node source) {
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source instanceof UntrustedFlowSource and
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not WithValidation::flow(source, _)
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}
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predicate isSink(DataFlow::Node sink) {
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sink = any(JwtUnverifiedParse parseUnverified).getTokenArg()
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}
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predicate isAdditionalFlowStep(DataFlow::Node nodeFrom, DataFlow::Node nodeTo) {
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golangJwtIsAdditionalFlowStep(nodeFrom, nodeTo)
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or
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goJoseIsAdditionalFlowStep(nodeFrom, nodeTo)
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}
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}
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module WithValidation = TaintTracking::Global<WithValidationConfig>;
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module NoValidation = TaintTracking::Global<NoValidationConfig>;
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import NoValidation::PathGraph
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from NoValidation::PathNode source, NoValidation::PathNode sink
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where NoValidation::flowPath(source, sink)
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select sink.getNode(), source, sink,
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"This JWT is parsed without verification and received from $@.", source.getNode(),
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"this user-controlled source"

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