CoreLabs Articles

Read articles from CoreLabs, the research division of Core Security. CoreLabs prides itself on taking a holistic view of information security with a focus on developing solutions to complex, real-world security problems that affect our customers.


Jun 17, 2021
In part 8, we solved ABO3 using IDA FREE. In this part, we’ll use Radare to solve ABO4. Updating Radare and Cutter First, we’ll need to update to the new version of Cutter, the Radare GUI. A pop-up will prompt us to update whenever there is a new version:
May 18, 2021
CVE-2021-26897 is a DNS server RCE vulnerability, and is triggered when many consecutive Signature RRs Dynamic Updates are sent. This vulnerability is an OOB write on the heap when combining the many consecutive Signature RR Dynamic Updates into base64-encoded strings before writing to the Zone file.
Apr 29, 2021
In part 7, we solved ABO2 in GHIDRA. In this part, we’ll use IDA FREE to solve ABO3. As is the case with all of the ABOS, the goal is to run the calculator or some other executable that we want. 
Mar 30, 2021
The new format of Microsoft monthly updates have proven challenging to reverse engineer. We’ve figured out a workaround that we hope will be helpful. In the original format, the Microsoft updates have always included the full files to patch, and from there it’s relatively straightforward to work on reversing and diffing through only extracting, without installing the patch.
Mar 18, 2021
Ransomware, as an active variant of current malware, has undoubtedly undergone a series of changes that have allowed cyber criminals to expand the horizons of clandestine business. In order to try to understand the different "forms" ransomware has presented over time, this article will show the evolutionary line of this latent threat in a compact and concrete way.
Mar 10, 2021
Authored by: Ernesto Alvarez, Senior Security Consultant, Security Consulting Services This article describes techniques used for creating UDP redirectors for protecting Cobalt Strike team servers. This is one of the recommended mechanisms for hiding Cobalt Strike team servers and involves adding different points which a Beacon can contact for instructions when using the HTTP channel.
Mar 4, 2021
The pen testing world is constantly changing and threat actors are continually finding new ways to exploit organizations of all industries and sizes. In order for pen testers to safely and efficiently test and expose security weaknesses, they enlist the help of different tools. This article series from cybersecurity expert Ricardo Narvaja provides tips and tricks on reversing and exploiting Windows using free and easy to get tools.
Feb 25, 2021
In part 6, we learned how to understand a shellcode and its resolver. Now, we will continue with the analysis and resolution of abo2 in GHIDRA. Download ABO2 executable. The latest version is on Google drive.
Feb 17, 2021
As you may already know, when a penetration test or Red Team exercise in being executed, it is important to define the objective of the project. Sometimes it is not enough to get Domain Admin privileges, so the objective may instead be defined as access to a particular network segment or a user’s workstation where credentials and sensitive information could be stored. For the purposes of this example, we’ll make the latter our main objective. With this in mind, let’s discuss the role DPAPI keys can play in such an attack. 
Feb 15, 2021
Authored by: Marcos Accossatto On August 5th, ethical hacker and cybersecurity professional Antoine Goichot posted on twitter that three vulnerabilities he had discovered on Cisco AnyConnect (CVE-2020-3433, CVE-2020-3434, and CVE-2020-3435) were now public. The next day, he published a follow-up blogpost on github.
Dec 18, 2020
Authored by: Ramiro Molina
Dec 15, 2020
In part 5, we completed our analysis of Stack4 using IDA Free. In this next part, we’ll be solving ABO1, using RADARE. The first thing we need to do is to find the binary information located in ABO1_VS_2017.exe. Go to the folder where the executable is and extract it using rabin2. Using RABIN2 rabin2 -l ABO1_VS_2017.exe
Oct 2, 2020
Authored by: Ricardo Narvaja Note: This work was originally done by Cristian Rubio and Ricardo Narvaja of Core Labs on Windows Server 2008 SP1 32 and 64-bit. There are not many differences in other versions of Windows. While the basis of the SIGred bug is quite simple, it’s critical to explore exactly how this vulnerability can exploited.
Sep 17, 2020
What You Need to Know About Netlogon and Zerologon On September 11th, 2020, researchers at Secura published information on a critical vulnerability in Microsoft’s Netlogon authentication process which they dubbed “Zerologon." It is a cryptographic flaw that has a clear path to full takeover of an Active Directory domain.
Jun 8, 2020
In part four, we performed an analysis of stacks three and four with exercises on testing bad characters. In this next part, we will complete our analysis of Stack4 using IDA Free. In subsequent parts, we’ll complete ABOS exercises that delve deeper into the use of the different tools.
Mar 9, 2020
In part three, we learned how to analyze the first two exercises (stacks), using the three interactive disassemblers, IDA FREE, RADARE, and GHIDRA. In this next part, we will continue our analysis with stack three and stack four. However, before that we need to introduce the new concept of invalid or bad chars.
Feb 18, 2020
In part two of this series, we learned to solve the exercise stack1 using x64dbg, debugging tool that allows us to analyze a program by running it, tracing it, even allowing us to set breakpoints, etc.
Feb 5, 2020
Core Labs has completed an in-depth analysis of two Microsoft vulnerabilities, CVE-2019-1181 and CVE-2019-1182, which were patched in August 2019. These vulnerabilities are particularly interesting and worth further assessment because they affect OS versions ranging from Windows 7 to Windows 10 1903 (x86, x86-64 and ARM64).
Jan 20, 2020
Zeppelin is the latest member of the VegaLocker ransomware family, which also contains strains like Jamper, Storm, or Buran. Zeppelin is an example of well-organized threat actors, as those behind Zeppelin have been incredibly strategic in carefully targeting these ransomware attacks. First spotted in November 2019, Zeppelin has been targeting primarily large companies in Europe and the United States.     
Jan 15, 2020
A Core Impact module was released on January 14, 2020 to exploit an as-yet unpatched patch traversal flaw in Citrix Application Delivery Controller (ADC) and Gateway (formerly known as NetScaler ADC & NetScaler Gateway) identified as CVE-2019-19781.
Jan 7, 2020
In part one of this series, we focused on installing several tools that will be useful for reversing and exploiting security weaknesses on Windows. These tools are free to access, so anyone can use them to learn and try out the useful exercises
Dec 25, 2019
Pen testing is a dynamic process that requires practitioners to exploit an environment to expose security weaknesses. In order to do this safely and efficiently, pen testers enlist the help of different tools. This article series will focus on reversing and exploiting Windows using free and easy to get tools, such as IDA FREE, Radare, Windbg, X64dbg, or Ghidra.
Dec 9, 2019
During hardware-oriented engagements, we are sometimes faced with a hardware device's firmware image. This may happen because we downloaded a firmware upgrade image to try to understand a device with a view of finding security flaws...
Dec 9, 2019
In the first series of this introduction to Linux and flash, we began with a basic lesson on flash memory. In part two, we can begin to tackle how Linux interacts with it. From this point forward, we’ll focus on NAND flash, with the following assumptions...
Dec 9, 2019
The latest and greatest in Linux-MTD is UBI and UBIfs. It is important to keep in mind that UBI is not the same as UBIfs. These two are actually two layers in a stack. UBI UBI (unsorted block images) is an abstraction layer that rides