Windows-based CLI susceptible to process injection attack

The fresh hacking technique could hide malware in legitimate apps


Hackers could exploit a fresh process injection technique to conceal malware in a Windows-based CLI app

Rotem Kerner, a security researcher with cybersecurity firm enSilo, discovered and dubbed the technique "Ctrl-Inject". It abuses the Windows "CtrlRoutine" function, a function that provides the mechanism for handling Ctrl signals in console application.

Ctrl-Inject basically causes malicious threads to spawn inside the processes of legitimate CLI apps, which then allows malicious code to be run. 

Every time a user (or a process) sends Ctrl + C (or Break) signal to a console-based process (such as cmd.exe or powershell.exe), a system process called csrss.exe will invoke the function CtrlRoutine in a new thread on the targeted process.

Advertisement - Article continues below

"Essentially, in this process injection technique, we inject our code to the target process, but we never invoke it directly, that is, we never call CreateRemoteThread ourselves or alter execution flow using SetThreadContext. Instead, we are making csrss.exe invoke it for us which is far less suspicious since this a normal behaviour," said Kerner.

Among the applications that hackers could abuse are cmd.exe or powershell.exe, commonly found in most Windows systems. Normally, app processes can't be tampered with as Windows uses security protections such as Control Flow Guard and pointer encoding to verify such processes.

However, Kerner said in a blog post detailing the technical aspects of the flaw, that it was possible to bypass such protections.

Kerner said that a hacker could use the same function to create their own thread in a legitimate CLI app's process and run malware code. He said the main advantage of this technique over classic thread injection technique is that the remote thread is created by a trusted windows process, csrss.exe, which makes it much stealthier.

"The disadvantage is that it's limited to console application," he added.

Featured Resources

The IT Pro guide to Windows 10 migration

Everything you need to know for a successful transition

Download now

Managing security risk and compliance in a challenging landscape

How key technology partners grow with your organisation

Download now

Software-defined storage for dummies

Control storage costs, eliminate storage bottlenecks and solve storage management challenges

Download now

6 best practices for escaping ransomware

A complete guide to tackling ransomware attacks

Download now



Google confirms Android cameras can be hijacked to spy on you

20 Nov 2019

Most Popular

Microsoft Azure

Microsoft, not Amazon, is going to win the cloud wars

30 Nov 2019
Amazon Web Services (AWS)

What to expect from AWS Re:Invent 2019

29 Nov 2019
Business strategy

Huawei takes the US trade sanctions into its own hands

3 Dec 2019

Five signs that it’s time to retire IT kit

29 Nov 2019