|
| 1 | +/** |
| 2 | + * @name Missing JWT signature check |
| 3 | + * @description Not checking the JWT signature allows an attacker to forge their own tokens. |
| 4 | + * @kind problem |
| 5 | + * @problem.severity error |
| 6 | + * @precision high |
| 7 | + * @id java/missing-jwt-signature-check |
| 8 | + * @tags security |
| 9 | + * external/cwe/cwe-347 |
| 10 | + */ |
| 11 | + |
| 12 | +import java |
| 13 | +import semmle.code.java.dataflow.DataFlow |
| 14 | + |
| 15 | +/** The interface `io.jsonwebtoken.JwtParser`. */ |
| 16 | +class TypeJwtParser extends Interface { |
| 17 | + TypeJwtParser() { this.hasQualifiedName("io.jsonwebtoken", "JwtParser") } |
| 18 | +} |
| 19 | + |
| 20 | +/** The interface `io.jsonwebtoken.JwtParser` or a type derived from it. */ |
| 21 | +class TypeDerivedJwtParser extends RefType { |
| 22 | + TypeDerivedJwtParser() { this.getASourceSupertype*() instanceof TypeJwtParser } |
| 23 | +} |
| 24 | + |
| 25 | +/** The interface `io.jsonwebtoken.JwtParserBuilder`. */ |
| 26 | +class TypeJwtParserBuilder extends Interface { |
| 27 | + TypeJwtParserBuilder() { this.hasQualifiedName("io.jsonwebtoken", "JwtParserBuilder") } |
| 28 | +} |
| 29 | + |
| 30 | +/** The interface `io.jsonwebtoken.JwtHandler`. */ |
| 31 | +class TypeJwtHandler extends Interface { |
| 32 | + TypeJwtHandler() { this.hasQualifiedName("io.jsonwebtoken", "JwtHandler") } |
| 33 | +} |
| 34 | + |
| 35 | +/** The class `io.jsonwebtoken.JwtHandlerAdapter`. */ |
| 36 | +class TypeJwtHandlerAdapter extends Class { |
| 37 | + TypeJwtHandlerAdapter() { this.hasQualifiedName("io.jsonwebtoken", "JwtHandlerAdapter") } |
| 38 | +} |
| 39 | + |
| 40 | +/** The `parse(token, handler)` method defined in `JwtParser`. */ |
| 41 | +private class JwtParserParseHandlerMethod extends Method { |
| 42 | + JwtParserParseHandlerMethod() { |
| 43 | + this.hasName("parse") and |
| 44 | + this.getDeclaringType() instanceof TypeJwtParser and |
| 45 | + this.getNumberOfParameters() = 2 |
| 46 | + } |
| 47 | +} |
| 48 | + |
| 49 | +/** The `parse(token)`, `parseClaimsJwt(token)` and `parsePlaintextJwt(token)` methods defined in `JwtParser`. */ |
| 50 | +private class JwtParserInsecureParseMethod extends Method { |
| 51 | + JwtParserInsecureParseMethod() { |
| 52 | + this.hasName(["parse", "parseClaimsJwt", "parsePlaintextJwt"]) and |
| 53 | + this.getNumberOfParameters() = 1 and |
| 54 | + this.getDeclaringType() instanceof TypeJwtParser |
| 55 | + } |
| 56 | +} |
| 57 | + |
| 58 | +/** The `on(Claims|Plaintext)Jwt` methods defined in `JwtHandler`. */ |
| 59 | +private class JwtHandlerOnJwtMethod extends Method { |
| 60 | + JwtHandlerOnJwtMethod() { |
| 61 | + this.hasName(["onClaimsJwt", "onPlaintextJwt"]) and |
| 62 | + this.getNumberOfParameters() = 1 and |
| 63 | + this.getDeclaringType() instanceof TypeJwtHandler |
| 64 | + } |
| 65 | +} |
| 66 | + |
| 67 | +/** The `on(Claims|Plaintext)Jwt` methods defined in `JwtHandlerAdapter`. */ |
| 68 | +private class JwtHandlerAdapterOnJwtMethod extends Method { |
| 69 | + JwtHandlerAdapterOnJwtMethod() { |
| 70 | + this.hasName(["onClaimsJwt", "onPlaintextJwt"]) and |
| 71 | + this.getNumberOfParameters() = 1 and |
| 72 | + this.getDeclaringType() instanceof TypeJwtHandlerAdapter |
| 73 | + } |
| 74 | +} |
| 75 | + |
| 76 | +/** |
| 77 | + * Holds if `parseHandlerExpr` is an insecure `JwtHandler`. |
| 78 | + * That is, it overrides a method from `JwtHandlerOnJwtMethod` and the override is not defined on `JwtHandlerAdapter`. |
| 79 | + * `JwtHandlerAdapter`'s overrides are safe since they always throw an exception. |
| 80 | + */ |
| 81 | +private predicate isInsecureJwtHandler(Expr parseHandlerExpr) { |
| 82 | + exists(RefType t | |
| 83 | + parseHandlerExpr.getType() = t and |
| 84 | + t.getASourceSupertype*() instanceof TypeJwtHandler and |
| 85 | + exists(Method m | |
| 86 | + m = t.getAMethod() and |
| 87 | + m.getASourceOverriddenMethod+() instanceof JwtHandlerOnJwtMethod and |
| 88 | + not m.getSourceDeclaration() instanceof JwtHandlerAdapterOnJwtMethod |
| 89 | + ) |
| 90 | + ) |
| 91 | +} |
| 92 | + |
| 93 | +/** |
| 94 | + * An access to an insecure parsing method. |
| 95 | + * That is, either a call to a `parse(token)`, `parseClaimsJwt(token)` or `parsePlaintextJwt(token)` method or |
| 96 | + * a call to a `parse(token, handler)` method where the `handler` is considered insecure. |
| 97 | + */ |
| 98 | +private class JwtParserInsecureParseMethodAccess extends MethodAccess { |
| 99 | + JwtParserInsecureParseMethodAccess() { |
| 100 | + this.getMethod().getASourceOverriddenMethod*() instanceof JwtParserInsecureParseMethod |
| 101 | + or |
| 102 | + this.getMethod().getASourceOverriddenMethod*() instanceof JwtParserParseHandlerMethod and |
| 103 | + isInsecureJwtHandler(this.getArgument(1)) |
| 104 | + } |
| 105 | +} |
| 106 | + |
| 107 | +/** |
| 108 | + * Holds if `signingMa` directly or indirectly sets a signing key for `expr`, which is a `JwtParser`. |
| 109 | + * The `setSigningKey` and `setSigningKeyResolver` methods set a signing key for a `JwtParser`. |
| 110 | + * Directly means code like this: |
| 111 | + * ```java |
| 112 | + * Jwts.parser().setSigningKey(key).parse(token); |
| 113 | + * ``` |
| 114 | + * Here the signing key is set directly on a `JwtParser`. |
| 115 | + * Indirectly means code like this: |
| 116 | + * ```java |
| 117 | + * Jwts.parserBuilder().setSigningKey(key).build().parse(token); |
| 118 | + * ``` |
| 119 | + * In this case, the signing key is set on a `JwtParserBuilder` indirectly setting the key of `JwtParser` that is created by the call to `build`. |
| 120 | + */ |
| 121 | +private predicate isSigningKeySetter(Expr expr, MethodAccess signingMa) { |
| 122 | + any(SigningToInsecureMethodAccessDataFlow s) |
| 123 | + .hasFlow(DataFlow::exprNode(signingMa), DataFlow::exprNode(expr)) |
| 124 | +} |
| 125 | + |
| 126 | +/** |
| 127 | + * An expr that is a (sub-type of) `JwtParser` for which a signing key has been set and which is used as |
| 128 | + * the qualifier to a `JwtParserInsecureParseMethodAccess`. |
| 129 | + */ |
| 130 | +private class JwtParserWithSigningKeyExpr extends Expr { |
| 131 | + MethodAccess signingMa; |
| 132 | + |
| 133 | + JwtParserWithSigningKeyExpr() { |
| 134 | + this.getType() instanceof TypeDerivedJwtParser and |
| 135 | + isSigningKeySetter(this, signingMa) |
| 136 | + } |
| 137 | + |
| 138 | + /** Gets the method access that sets the signing key for this parser. */ |
| 139 | + MethodAccess getSigningMethodAccess() { result = signingMa } |
| 140 | +} |
| 141 | + |
| 142 | +/** |
| 143 | + * Models flow from `SigningKeyMethodAccess`es to qualifiers of `JwtParserInsecureParseMethodAccess`es. |
| 144 | + * This is used to determine whether a `JwtParser` has a signing key set. |
| 145 | + */ |
| 146 | +private class SigningToInsecureMethodAccessDataFlow extends DataFlow::Configuration { |
| 147 | + SigningToInsecureMethodAccessDataFlow() { this = "SigningToExprDataFlow" } |
| 148 | + |
| 149 | + override predicate isSource(DataFlow::Node source) { |
| 150 | + source.asExpr() instanceof SigningKeyMethodAccess |
| 151 | + } |
| 152 | + |
| 153 | + override predicate isSink(DataFlow::Node sink) { |
| 154 | + any(JwtParserInsecureParseMethodAccess ma).getQualifier() = sink.asExpr() |
| 155 | + } |
| 156 | + |
| 157 | + /** Models the builder style of `JwtParser` and `JwtParserBuilder`. */ |
| 158 | + override predicate isAdditionalFlowStep(DataFlow::Node pred, DataFlow::Node succ) { |
| 159 | + ( |
| 160 | + pred.asExpr().getType() instanceof TypeDerivedJwtParser or |
| 161 | + pred.asExpr().getType().(RefType).getASourceSupertype*() instanceof TypeJwtParserBuilder |
| 162 | + ) and |
| 163 | + succ.asExpr().(MethodAccess).getQualifier() = pred.asExpr() |
| 164 | + } |
| 165 | +} |
| 166 | + |
| 167 | +/** An access to the `setSigningKey` or `setSigningKeyResolver` method (or an overridden method) defined in `JwtParser` and `JwtParserBuilder`. */ |
| 168 | +private class SigningKeyMethodAccess extends MethodAccess { |
| 169 | + SigningKeyMethodAccess() { |
| 170 | + exists(Method m | |
| 171 | + m.hasName(["setSigningKey", "setSigningKeyResolver"]) and |
| 172 | + m.getNumberOfParameters() = 1 and |
| 173 | + ( |
| 174 | + m.getDeclaringType() instanceof TypeJwtParser or |
| 175 | + m.getDeclaringType() instanceof TypeJwtParserBuilder |
| 176 | + ) |
| 177 | + | |
| 178 | + m = this.getMethod().getASourceOverriddenMethod*() |
| 179 | + ) |
| 180 | + } |
| 181 | +} |
| 182 | + |
| 183 | +/** |
| 184 | + * Holds if the `MethodAccess` `ma` occurs in a test file. A test file is any file that |
| 185 | + * is a direct or indirect child of a directory named `test`, ignoring case. |
| 186 | + */ |
| 187 | +private predicate isInTestFile(MethodAccess ma) { |
| 188 | + exists(string lowerCasedAbsolutePath | |
| 189 | + lowerCasedAbsolutePath = ma.getLocation().getFile().getAbsolutePath().toLowerCase() |
| 190 | + | |
| 191 | + lowerCasedAbsolutePath.matches("%/test/%") and |
| 192 | + not lowerCasedAbsolutePath |
| 193 | + .matches("%/ql/test/experimental/query-tests/security/CWE-347/%".toLowerCase()) |
| 194 | + ) |
| 195 | +} |
| 196 | + |
| 197 | +from JwtParserInsecureParseMethodAccess ma, JwtParserWithSigningKeyExpr parserExpr |
| 198 | +where ma.getQualifier() = parserExpr and not isInTestFile(ma) |
| 199 | +select ma, "A signing key is set $@, but the signature is not verified.", |
| 200 | + parserExpr.getSigningMethodAccess(), "here" |
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