Detecting dangerous RMI objects with CodeQL

Java RMI uses the default Java deserialization mechanism for passing parameters during remote method invocations. In other words, RMI uses ObjectInputStream that is a well-known unsafe deserialization mechanism. If an attacker can find and send a deserialization gadget to a vulnerable remote method, in the worst case it can result in arbitrary code execution.

I recently wrote a CodeQL query that looks for dangerous remote objects registered in an RMI registry. This post describes the vulnerability and how the query works.

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WS-2016-7107: CSRF tokens in Spring and the BREACH attack

Recently WhiteSource security scanner started reporting WS-2016-7107 against Spring-based applications. This is an old issue in Spring Security that was reported in 2016. Unfortunately, at the moment of writing it, the issue has not been fixed yet. But there is a pull request that should address it. The problem is that CSRF tokens generated by Spring Security are vulnerable to the BREACH attack. The attack is even older — it was published in 2013. The BREACH attack is similar to the CRIME attack but BREACH doesn’t need TLS compression.

(you can also read it on Medium)

WS-2016-7107: CSRF tokens in Spring and the BREACH attack
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Detecting dangerous Spring service exporters with CodeQL

In this blog post, I’ll talk about detecting unsafe Spring Exporters with a CodeQL query. First, I’ll describe the issue that received CVE-2016-1000027. Next, I’ll show what a vulnerable code looks like and how the issue can be mitigated in an application. Then, I’ll describe how the CodeQL query works. In addition, I’ll show a couple of vulnerabilities that have been found by the query.

(you can also read it on Medium)

Detecting dangerous Spring Exporters with CodeQL
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Fosstars: a framework for defining ratings for open source projects

I recently wrote a blog post about a project I have been working on at SAP for a year. The project is called Fosstars. It is an open-source Java-based framework for defining ratings that help to assess security, activity and other properties of open source projects. Currently, Fosstars offers a comprehensive security rating that helps to identify open source components that can be a security risk for an application. The blog post describes how Fosstars work:

https://blogs.sap.com/2021/02/09/fosstars-a-framework-for-defining-ratings-for-open-source-projects/

I am planning to write a few more articles. One is going to talk about the security rating in detail, and another one is going to be about calculating security ratings with Fosstars and GitHub actions.

Detecting JEXL injections with CodeQL

In this post, I’ll talk about a CodeQL query for detecting JEXL Expression Language injection vulnerabilities. First, I’ll give a brief overview of expression languages in general and JEXL in particular. Next, I’ll explain what Expression Language injection is and how to prevent it. Then, I’ll describe how the CodeQL query works. In addition, I’ll show a couple of vulnerabilities that have been found by the query.

(you can also read it on Medium)

Detecting JEXL injections with CodeQL
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Reading a photoresistor on ESP32 with MicroPython

A photoresistor or a light-dependent resistor (LDR) is a resistor that changes its value (resistance) depending on light intensity. More precisely, when light falls upon it, the resistance decreases. It is normally used as a light or dark detector. For example, it may be used in a circuit that turns lights in a room on when it gets dark. Let’s see how we use a photoresistor with ESP32 and MicroPython.

ESP32 and photoresistor
by Alena Penkova
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Measuring CO2 with MH-Z19B on ESP32 with MicroPython

In the previous posts, I described a simple weather station that measures temperature and humidity and sends the measurements to a Google sheet. The system is supposed to be used at home. Therefore, one of the next possible improvements can be measuring air quality in a room. That can be done, for example, by adding an MH-Z19B sensor for measuring CO2 level. We’ll use again a ESP32 board and MicroPython.

Measuring CO2 with MH-Z19B sensor on ESP32
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New Switch Expressions in Java 14

Java 14 is going to be released on March 17, 2020. The new version of Java contains one major update to the Java language: new switch expressions. Let’s see how the new switch expressions can be used, what kind of advantages they offer, and what can potentially go wrong. In the end, you are going to find a tricky question about the switch expressions.

(the article has been published on Medium)

New Switch Expressions in Java 14
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What is new in Java 14?

Java 14 is going to be released on Mar 17th, 2020. Besides ~2400 bug fixes and small enhancements, the new version of Java contains 16 major enhancements which are also called JEPs (Java Enhancement Proposals).

Let’s take a closer look at the major updates in Java 14: new switch expressions, better NullPointerExceptions, improvements in garbage collection, JFR event streaming and more.

(the article has been published on Medium)

What is new in Java 14
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