Potential fix for code scanning alert no. 10: XPath injection #35
Conversation
Co-authored-by: Copilot Autofix powered by AI <62310815+github-advanced-security[bot]@users.noreply.github.com>
There was a problem hiding this comment.
Pull request overview
This pull request attempts to address XPath injection vulnerabilities in the FindSalesPerson method by adding input validation and normalization. While the changes introduce protective measures, they do not fully eliminate the underlying security risk.
- Added regex validation to restrict state input to 2-letter alphabetic strings
- Converted state input to lowercase for consistent matching
- Added silent validation failure handling that returns early on invalid input
💡 Add Copilot custom instructions for smarter, more guided reviews. Learn how to get started.
| XmlDocument xDoc = new XmlDocument(); | ||
| xDoc.LoadXml(xml); | ||
| XmlNodeList list = xDoc.SelectNodes("//salesperson[state='" + state + "']"); | ||
| XmlNodeList list = xDoc.SelectNodes("//salesperson[state='" + state.ToLower() + "']"); |
There was a problem hiding this comment.
The XPath query is still vulnerable to injection attacks despite the input validation. While the regex check limits input to 2 letters, string concatenation remains unsafe for constructing XPath queries. Consider using XPath parameterization with XPathExpression and SetContext, or use LINQ to XML which provides safer query mechanisms. For example, you could use XmlDocument.SelectNodes with XPathNavigator and compile the expression, or migrate to LINQ to XML's safer querying approach.
| private void FindSalesPerson(string state) | ||
| { | ||
| // Accept only alphabetic 2-letter abbreviations for state (e.g., "ny", "ca") | ||
| if (string.IsNullOrEmpty(state) || !System.Text.RegularExpressions.Regex.IsMatch(state, "^[a-zA-Z]{2}$")) |
There was a problem hiding this comment.
The fully qualified namespace is unnecessary here since RegularExpressions is already imported at line 9. Use Regex.IsMatch directly instead of System.Text.RegularExpressions.Regex.IsMatch for better code readability and consistency with the import statement.
| if (string.IsNullOrEmpty(state) || !System.Text.RegularExpressions.Regex.IsMatch(state, "^[a-zA-Z]{2}$")) | |
| if (string.IsNullOrEmpty(state) || !Regex.IsMatch(state, "^[a-zA-Z]{2}$")) |
| // Accept only alphabetic 2-letter abbreviations for state (e.g., "ny", "ca") | ||
| if (string.IsNullOrEmpty(state) || !System.Text.RegularExpressions.Regex.IsMatch(state, "^[a-zA-Z]{2}$")) | ||
| { | ||
| // Invalid state input, do not proceed or handle accordingly | ||
| return; |
There was a problem hiding this comment.
Silent failure on invalid input may lead to confusion for users and make debugging difficult. Consider logging the validation failure or returning an appropriate error message to inform the caller why no results were returned. This would help distinguish between "no salespeople found in that state" versus "invalid state code provided".
1 participant
This pull request improves input validation and security for the
FindSalesPersonmethod inXPathInjection.aspx.cs. The main change is the introduction of strict input validation for thestateparameter, ensuring only valid 2-letter alphabetic state codes are accepted, and normalizing input to lowercase before using it in an XPath query.Input validation and security improvements:
stateparameter is a non-empty, 2-letter alphabetic string using a regular expression, preventing invalid or malicious input from being used in the XPath query.stateparameter to lowercase before passing it to the XPath query, ensuring consistent matching and reducing case sensitivity issues.System.Text.RegularExpressionsimport to support the new input validation logic.