Add a rule to detect the usage of ssh InsecureIgnoreHostKey function

Author: Cosmin Cojocar

rules/rulelist.go

@@ -65,6 +65,7 @@ func Generate(filters ...RuleFilter) RuleList {
 		"G103": RuleDefinition{"Audit the use of unsafe block", NewUsingUnsafe},
 		"G104": RuleDefinition{"Audit errors not checked", NewNoErrorCheck},
 		"G105": RuleDefinition{"Audit the use of big.Exp function", NewUsingBigExp},
+		"G106": RuleDefinition{"Audit the use of ssh.InsecureIgnoreHostKey function", NewSSHHostKey},
 
 		// injection
 		"G201": RuleDefinition{"SQL query construction using format string", NewSQLStrFormat},

rules/rules_test.go

@@ -65,6 +65,10 @@ var _ = Describe("gas rules", func() {
 			runner("G105", testutils.SampleCodeG105)
 		})
 
+		It("should detect of ssh.InsecureIgnoreHostKey function", func() {
+			runner("G106", testutils.SampleCodeG106)
+		})
+
 		It("should detect sql injection via format strings", func() {
 			runner("G201", testutils.SampleCodeG201)
 		})

rules/ssh.go

@@ -0,0 +1,47 @@
+// (c) Copyright 2016 Hewlett Packard Enterprise Development LP
+//
+// Licensed under the Apache License, Version 2.0 (the "License");
+// you may not use this file except in compliance with the License.
+// You may obtain a copy of the License at
+//
+//     http://www.apache.org/licenses/LICENSE-2.0
+//
+// Unless required by applicable law or agreed to in writing, software
+// distributed under the License is distributed on an "AS IS" BASIS,
+// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+// See the License for the specific language governing permissions and
+// limitations under the License.
+
+package rules
+
+import (
+	"go/ast"
+
+	"github.com/GoASTScanner/gas"
+)
+
+type sshHostKey struct {
+	gas.MetaData
+	pkg   string
+	calls []string
+}
+
+func (r *sshHostKey) Match(n ast.Node, c *gas.Context) (gi *gas.Issue, err error) {
+	if _, matches := gas.MatchCallByPackage(n, c, r.pkg, r.calls...); matches {
+		return gas.NewIssue(c, n, r.What, r.Severity, r.Confidence), nil
+	}
+	return nil, nil
+}
+
+// NewSSHHostKey rule detects the use of insecure ssh HostKeyCallback.
+func NewSSHHostKey(conf gas.Config) (gas.Rule, []ast.Node) {
+	return &sshHostKey{
+		pkg:   "golang.org/x/crypto/ssh",
+		calls: []string{"InsecureIgnoreHostKey"},
+		MetaData: gas.MetaData{
+			What:       "Use of ssh InsecureIgnoreHostKey should be audited",
+			Severity:   gas.Medium,
+			Confidence: gas.High,
+		},
+	}, []ast.Node{(*ast.CallExpr)(nil)}
+}

testutils/source.go

@@ -183,6 +183,15 @@ func main() {
     z = z.Exp(x, y, m)
 }`, 1}}
 
+	// SampleCodeG106 - ssh InsecureIgnoreHostKey
+	SampleCodeG106 = []CodeSample{{`
+package main
+import (
+        "golang.org/x/crypto/ssh"
+)
+func main() {
+        _ :=  ssh.InsecureIgnoreHostKey()
+}`, 1}}
 	// SampleCodeG201 - SQL injection via format string
 	SampleCodeG201 = []CodeSample{
 		{`