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Date: Thu, 28 Sep 2023 17:20:25 +0530
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Subject: VULNERABILITY REPORT: DLL Hijacking Vulnerability in CygWin
 setup-x86_64.exe
To: cygwin AT cygwin DOT com
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From: Suman Chakraborty via Cygwin <cygwin AT cygwin DOT com>
Reply-To: Suman Chakraborty <chakrabortysuman487 AT gmail DOT com>
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Sender: "Cygwin" <cygwin-bounces+archive-cygwin=delorie DOT com AT cygwin DOT com>

Hey Cygwin Team,

I hope this email finds you well. As an independent security researcher, I
often explore open-source projects to identify and report potential
security vulnerabilities. During my recent exploration of Cygwin, I came
across a critical vulnerability in setup-x86_64.exe
<https://cygwin.com/setup-x86_64.exe> that I believe warrants your
immediate attention.

1. Executive Summary:

The vulnerability pertains to not finding the profapi.dll and insecure
loading of dynamic link libraries (DLLs), specifically profapi.dll. If
exploited, this vulnerability could allow an attacker to execute arbitrary
code on a victim's machine, potentially leading to data breaches, system
compromise, and other malicious activities.

2. Details of the Vulnerability:

Type: DLL Hijacking
Affected Component: profapi.dll
Impact: Remote Code Execution, Data Theft or
Manipulation, Persistence, Bypassing Security Mechanisms, Spreading Malware.
Description: The application attempts to load profapi.dll from its current
working directory (CWD). If a malicious version of test.dll is present in
the CWD, the application will inadvertently load and execute the malicious
DLL.

3. Proof of Concept:

I've attached a proof of concept to this email, demonstrating the
vulnerability in action. Please review it to understand the potential
impact and exploitability.
The link is given below:
POC Video:
https://drive.google.com/file/d/11rBPnImiZS-CEwPM9eBlU6GSHjHYD2ns/view?usp=sharing

4. Recommended Mitigation:

To address this vulnerability, I recommend the following steps:

Explicit Path Specification: Always use a full path when loading DLLs to
ensure the application loads the correct DLL from the intended location.
Safe DLL Loading: Implement the use of the LOAD_LIBRARY_SEARCH_SYSTEM32
flag or similar secure methods when using functions like LoadLibrary or
LoadLibraryEx.
Manifests and Dependency Management: Use embedded manifests with the
dependency element to specify the paths of required DLLs.
Monitoring and Logging: Implement mechanisms to detect and alert on any
unexpected or unauthorized DLL loading events.
User Education: As this is an open-source project, it might be beneficial
to inform users about the risks of downloading and executing files from
untrusted sources.

5. Conclusion:

The identified DLL Hijacking vulnerability poses a significant risk to
users of Cygwin during the installation and executing the setup-x86_64.exe
<https://cygwin.com/setup-x86_64.exe>. I urge you to address this issue
promptly. I'm available for any further clarification or assistance in
addressing the vulnerability

Thank you for your attention to this matter, and I appreciate the hard work
you put into maintaining and improving open-source projects for the
community.Best regards,
Submitted by:
Suman Kumar Chakraborty
LinkedIn:https://www.linkedin.com/in/suman-chakraborty-b857901b1/

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