jsqlparser:实现基于SQL语法分析的SQL注入攻击检查
之前写过一篇博客：《java:正则表达式检查SQL WHERE条件语句防止注入攻击和常量表达式》,当前时通过正则表达式来检查SQL语句中是否有危险关键字和常量表达式实现SQL语句的注入攻击检查。坦率的说，这个办法是有漏洞的，误判，漏判的概率很大，基于当前我的知识能力，也只能做到这样。
最近学习了jsqlparser,我知道我找到了更好的办法来解决SQL注入攻击检查问题。
jsqlparser是一个java的SQL语句解析器，在上一篇博客：《jsqlparser:基于抽象语法树(AST)遍历SQL语句的语法元素》介绍了如何通过jsqlparser来遍历SQL语句中所有的字段和表名引用。
其实它可以用来进行更复杂的工作，jsqlparser会将一条SQL语句的各种语法元素以抽象语法树(AST，abstract syntax tree)形式解析为很多不同类型对象，通过对AST的遍历就可以对SQL语句进行分析。采用这种方式做SQL注入攻击检查不会有误判，漏判的问题。
SqlInjectionAnalyzer
SqlInjectionAnalyzer SQL注入攻击分析器
jsqlparse提供了两种式遍历SQL语句解析对象，一种是基于TablesNamesFinder，TablesNamesFinder其实是实现jsqparser很多对象访问接口的一个基类
一种是基于CCJSqlParserDefaultVisitor接口。
/**
* SQL注入攻击分析器
* @author guyadong
*
*/
public class SqlInjectionAnalyzer {
private boolean injectCheckEnable = true;
private final InjectionSyntaxObjectAnalyzer injectionChecker;
private final InjectionAstNodeVisitor injectionVisitor;
public SqlInjectionAnalyzer() {
this.injectionChecker = new InjectionSyntaxObjectAnalyzer();
this.injectionVisitor = new InjectionAstNodeVisitor();
}
/**
* 启用/关闭注入攻击检查,默认启动
* @param enable
* @return
*/
public SqlInjectionAnalyzer injectCheckEnable(boolean enable){
injectCheckEnable = enable;
return this;
}
/**
* 对解析后的SQL对象执行注入攻击分析，有注入攻击的危险则抛出异常{@link InjectionAttackException}
* @param sqlParserInfo
* @throws InjectionAttackException
*/
public SqlParserInfo injectAnalyse(SqlParserInfo sqlParserInfo) throws InjectionAttackException{
if(null != sqlParserInfo && injectCheckEnable){
/** SQL注入攻击检查 */
sqlParserInfo.statement.accept(injectionChecker);
sqlParserInfo.simpleNode.jjtAccept(injectionVisitor, null);
}
return sqlParserInfo;
}
}
InjectionSyntaxObjectAnalyzer
InjectionSyntaxObjectAnalyzer 为基于SQL语法对象的SQL注入攻击分析实现
TablesNamesFinder是jsqlparser提供的一个语法元素遍历对象，继承这个对象可以实现对需要的语法元素的访问，当遇到有注入攻击危险的表达式，语句时抛出InjectionAttackException异常，就是这个类做的工作
import net.sf.jsqlparser.expression.BinaryExpression;
import net.sf.jsqlparser.expression.Expression;
import net.sf.jsqlparser.expression.Function;
import net.sf.jsqlparser.expression.operators.conditional.AndExpression;
import net.sf.jsqlparser.expression.operators.conditional.OrExpression;
import net.sf.jsqlparser.expression.operators.relational.ComparisonOperator;
import net.sf.jsqlparser.schema.Column;
import net.sf.jsqlparser.statement.select.Join;
import net.sf.jsqlparser.statement.select.OrderByElement;
import net.sf.jsqlparser.statement.select.PlainSelect;
import net.sf.jsqlparser.statement.select.SelectItem;
import net.sf.jsqlparser.statement.select.SubSelect;
import net.sf.jsqlparser.statement.select.WithItem;
import net.sf.jsqlparser.util.TablesNamesFinder;
/**
* 基于SQL语法对象的SQL注入攻击分析实现
* @author guyadong
*
*/
public class InjectionSyntaxObjectAnalyzer extends TablesNamesFinder{
/** 危险函数名 */
private static final String DANGROUS_FUNCTIONS = "(sleep|benchmark|extractvalue|updatexml|ST_LatFromGeoHash|ST_LongFromGeoHash|GTID_SUBSET|GTID_SUBTRACT|floor|ST_Pointfromgeohash"
+ "|geometrycollection|multipoint|polygon|multipolygon|linestring|multilinestring)";
private static ThreadLocal<Boolean> disableSubselect = new ThreadLocal<Boolean>(){
@Override
protected Boolean initialValue() {
return true;
}};
private ConstAnalyzer constAnalyzer = new ConstAnalyzer();
public InjectionSyntaxObjectAnalyzer() {
super();
init(true);
}
@Override
public void visitBinaryExpression(BinaryExpression binaryExpression) {
if(binaryExpression instanceof ComparisonOperator){
if(isConst(binaryExpression.getLeftExpression()) && isConst(binaryExpression.getRightExpression())){
/** 禁用恒等式 */
throw new InjectionAttackException("DISABLE IDENTICAL EQUATION " + binaryExpression);
}
}
super.visitBinaryExpression(binaryExpression);
}
@Override
public void visit(AndExpression andExpression) {
super.visit(andExpression);
checkConstExpress(andExpression.getLeftExpression());
checkConstExpress(andExpression.getRightExpression());
}
@Override
public void visit(OrExpression orExpression) {
super.visit(orExpression);
checkConstExpress(orExpression.getLeftExpression());
checkConstExpress(orExpression.getRightExpression());
}
@Override
public void visit(Function function) {
if(function.getName().matches(DANGROUS_FUNCTIONS)){
/** 禁用危险函数 */
throw new InjectionAttackException("DANGROUS FUNCTION: "+function.getName());
}
super.visit(function);
}
@Override
public void visit(WithItem withItem) {
try {
/** 允许 WITH 语句中的子查询 */
disableSubselect.set(false);
super.visit(withItem);
} finally {
disableSubselect.set(true);
}
}
@Override
public void visit(SubSelect subSelect) {
if(disableSubselect.get()){
// 禁用子查询
throw new InjectionAttackException("DISABLE subselect " + subSelect);
}
}
@Override
public void visit(Column tableColumn) {
if(ParserSupport.isBoolean(tableColumn)){
throw new InjectionAttackException("DISABLE CONST BOOL " + tableColumn);
}
super.visit(tableColumn);
}
@Override
public void visit(PlainSelect plainSelect) {
if (plainSelect.getSelectItems() != null) {
for (SelectItem item : plainSelect.getSelectItems()) {
item.accept(this);
}
}
if (plainSelect.getFromItem() != null) {
plainSelect.getFromItem().accept(this);
}
if (plainSelect.getJoins() != null) {
for (Join join : plainSelect.getJoins()) {
join.getRightItem().accept(this);
for(Expression e:join.getOnExpressions()){
e.accept(this);
}
}
}
if (plainSelect.getWhere() != null) {
plainSelect.getWhere().accept(this);
checkConstExpress(plainSelect.getWhere());
}
if (plainSelect.getHaving() != null) {
plainSelect.getHaving().accept(this);
}
if (plainSelect.getOracleHierarchical() != null) {
plainSelect.getOracleHierarchical().accept(this);
}
if(plainSelect.getOrderByElements() != null){
for( OrderByElement orderByElement : plainSelect.getOrderByElements()){
orderByElement.getExpression().accept(this);
}
}
if(plainSelect.getGroupBy() != null){
for(Expression expression : plainSelect.getGroupBy().getGroupByExpressionList().getExpressions()){
expression.accept(this);
}
}
}
private boolean isConst(Expression expression){
return constAnalyzer.isConstExpression(expression);
}
private void checkConstExpress(Expression expression){
if(constAnalyzer.isConstExpression(expression)){
/** 禁用常量表达式 */
throw new InjectionAttackException("DISABLE CONST EXPRESSION " + expression);
}
}
}
InjectionAstNodeVisitor
InjectionAstNodeVisitor 为基于抽象语法树(AST)的注入攻击分析实现
这部分代码很少，实现禁用用UNION语句
import net.sf.jsqlparser.parser.CCJSqlParserDefaultVisitor;
import net.sf.jsqlparser.parser.SimpleNode;
import net.sf.jsqlparser.statement.select.UnionOp;
/**
* 基于抽象语法树(AST)的注入攻击分析实现
* @author guyadong
*
*/
public class InjectionAstNodeVisitor extends CCJSqlParserDefaultVisitor{
public InjectionAstNodeVisitor() {
}
@Override
public Object visit(SimpleNode node, Object data) {
Object value = node.jjtGetValue();
if(value instanceof UnionOp){
throw new InjectionAttackException("DISABLE UNION");
}
return super.visit(node, data);
}
}
单元测试
InjectAttackCheckerTest SQL注入攻击检查测试
import static org.junit.Assert.*;
import org.junit.BeforeClass;
import org.junit.Test;
import gu.sql2java.parser.InjectionAttackException;
import gu.sql2java.parser.ParserSupport;
import gu.sql2java.parser.SqlInjectionAnalyzer;
import gu.sql2java.parser.ParserSupport.SqlParserInfo;
import net.sf.jsqlparser.JSQLParserException;
import static gu.sql2java.SimpleLog.log;
/**
* SQL注入攻击检查测试
* @author guyadong
*
*/
public class InjectAttackCheckerTest {
private static SqlInjectionAnalyzer analyser;
@BeforeClass
public static void setUpBeforeClass() throws Exception {
analyser= new SqlInjectionAnalyzer();
}
private boolean injectAnalyse(String sql) throws JSQLParserException{
SqlParserInfo sqlParserInfo = ParserSupport.parse0(sql, null);
try {
analyser.injectAnalyse(sqlParserInfo);
return true;
} catch (InjectionAttackException e) {
log("{}",e.getMessage());
//log(e);
return false;
}
}
@Test
public void test() throws JSQLParserException {
assertFalse(injectAnalyse("select * from dc_device where id in (select id from other)"));
assertFalse(injectAnalyse("select * from dc_device where 2=2.0 or 2 != 4"));
assertFalse(injectAnalyse("select * from dc_device where 1!=2.0"));
assertFalse(injectAnalyse("select * from dc_device where id=floor(2.0)"));
assertFalse(injectAnalyse("select * from dc_device where not true"));
assertFalse(injectAnalyse("select * from dc_device where 1 or id > 0"));
assertFalse(injectAnalyse("select * from dc_device where 'tom' or id > 0"));
assertFalse(injectAnalyse("select * from dc_device where '-2.3' "));
assertFalse(injectAnalyse("select * from dc_device where 2 "));
assertFalse(injectAnalyse("select * from dc_device where (3+2) "));
assertFalse(injectAnalyse("select * from dc_device where -1 IS TRUE"));
assertFalse(injectAnalyse("select * from dc_device where 'hello' is null "));
assertFalse(injectAnalyse("select * from dc_device where '2022-10-31' and id > 0"));
assertFalse(injectAnalyse("select * from dc_device where id > 0 or 1!=2.0 "));
assertFalse(injectAnalyse("select * from dc_device where id > 0 or 1 in (1,3,4) "));
assertFalse(injectAnalyse("select * from dc_device UNION select name from other"));
assertTrue(injectAnalyse("WITH SUB1 AS (SELECT user FROM t1) SELECT * FROM T2 WHERE id > 123 "));
}
}
完整代码参见码云仓库：
https://gitee.com/l0km/sql2java/tree/dev/sql2java-manager/src/main/java/gu/sql2java/parser