This is the second installment in a series revisiting the User-Defined Reflective Loader (UDRL). In part one, we aimed to simplify the development and debugging of custom loaders and introduced the User-Defined Reflective Loader Visual Studio (UDRL-VS) template. In this installment, we’ll build upon the original UDRL-VS loader and explore how to apply our own […]
Read More… from Revisiting the User-Defined Reflective Loader Part 2: Obfuscation and Masking
Beacon Object Files (BOFs) were introduced in Cobalt Strike 4.1 in 2020. Since their release, BOFs have played a key role in post-exploitation activities, surpassing Reflective DLLs, .NET assemblies, and PowerShell scripts. However, in our experience, many developers struggle with four primary pain points: In this blog post, we will tackle these difficulties by introducing […]
Read More… from Simplifying BOF Development: Debug, Test, and Save Your B(e)acon
This is a joint blog written by the Cobalt Strike and Outflank teams. It is also available on the Outflank site. Over the past few months there has been increasing collaboration and knowledge sharing internally between the Cobalt Strike and Outflank R&D teams. We are excited about the innovation opportunities made possible by this teamwork and […]
Read More… from Cobalt Strike and Outflank Security Tooling: Friends in Evasive Places
Over the past few years, there has been a massive proliferation of YARA signatures for Beacon. We know from conversations with our customers that this has become problematic when using Cobalt Strike for red team engagements and that there has been some confusion over how Cobalt Strike’s malleable C2 options can help. Therefore, this blog […]
Read More… from Cobalt Strike and YARA: Can I Have Your Signature?
Microsoft’s Digital Crimes Unit (DCU), cybersecurity software company Fortra™ and Health Information Sharing and Analysis Center (Health-ISAC) are taking technical and legal action to disrupt cracked, legacy copies of Cobalt Strike and abused Microsoft software, which have been used by cybercriminals to distribute malware, including ransomware. This is a change in the way DCU has […]
Read More… from Stopping Cybercriminals From Abusing Security Tools
I blogged about the Cobalt Strike roadmap in March last year and while the fundamental tenets of our approach to R&D remain unaltered, a lot has changed behind the scenes over the past year or so. I try to engage with our customers on various platforms and over the past few months, I’ve been asked […]
Read More… from Cobalt Strike 2023 Roadmap and Strategy Update
This blog post accompanies a new addition to the Arsenal Kit – The User-Defined Reflective Loader Visual Studio (UDRL-VS). Over the past few months, we have received a lot of feedback from our users that whilst the flexibility of the UDRL is great, there is not enough information/example code to get the most out of […]
Read More… from Revisiting the User-Defined Reflective Loader Part 1: Simplifying Development
Cobalt Strike 4.8 is now available. This release sees support for system calls, options to specify payload guardrails, a new token store, and more. We had originally planned to get this release out late in 2022 but progress was stymied due to the 4.7.1 and 4.7.2 patch releases that we had to put out to […]
This blog introduces a PoC technique for spoofing call stacks using timers. Prior to our implant sleeping, we can queue up timers to overwrite its call stack with a fake one and then restore the original before resuming execution. Hence, in the same way we can mask memory belonging to our implant during sleep, we […]
Read More… from Behind the Mask: Spoofing Call Stacks Dynamically with Timers
Cobalt Strike 4.7.2 is now available. This is an out of band update to fix a remote code execution vulnerability that is rooted in Java Swing but which can be exploited in Cobalt Strike. Remote Code Execution Vulnerability I’d like to start by giving credit to Rio Sherri (0x09AL) and Ruben Boonen (FuzzySec) from the […]