Dirty COW: Zero day Vulnerability in Critical Linux Kernel

Zero day attack description : In 2016, the discovery of the Dirty COW vulnerability sent shockwaves through the Linux community. Dirty COW (Copy-On-Write) exposed a critical flaw in the Linux kernel that allowed attackers to gain root privileges on vulnerable systems. In this article, we delve into the technical details of Dirty COW, explore its potential risks, and discuss the mitigation efforts undertaken to address this widespread vulnerability.

Understanding Dirty COW:

Dirty COW is a privilege escalation vulnerability that resides in the Linux kernel’s handling of copy-on-write (COW) operations. It exploits a race condition that occurs when multiple processes simultaneously access the same memory page marked as copy-on-write. By manipulating this race condition, an attacker can gain write access to read-only memory mappings and modify critical system files.

  1. Race Condition Exploitation: Dirty COW leverages a race condition that occurs during the COW process. When a process attempts to modify a shared memory page marked as copy-on-write, the Linux kernel should create a separate copy of the page for that process. However, Dirty COW manipulates this process to gain write access to the shared page without creating a separate copy.
  2. Privilege Escalation: By gaining write access to read-only memory mappings, an attacker can modify critical system files, including binaries, libraries, and configuration files. This can lead to privilege escalation, allowing the attacker to gain root-level access on the compromised system.


Dirty COW posed significant risks to Linux-based systems, servers, and embedded devices. The vulnerability exposed by Dirty COW presented the following potential risks:

  1. Root-level Access: Exploiting Dirty COW could grant an attacker root-level access to the compromised system. This level of access allows the attacker to take full control of the system, install malware, modify system configurations, and manipulate or exfiltrate sensitive data.
  2. Persistence and Lateral Movement: With root privileges, attackers can establish persistent backdoors, maintain control over the compromised system, and pivot to other systems within the network. This poses a significant threat to organizations, as it allows for lateral movement and the potential compromise of additional systems.


Addressing the Dirty COW vulnerability required a combination of patches, updates, and diligent system administration practices. The following mitigation strategies were recommended:

  1. Patching and Updates: Linux distribution vendors, along with the Linux kernel development community, released patches to fix the Dirty COW vulnerability. System administrators were strongly advised to promptly apply these patches to vulnerable systems to prevent exploitation.
  2. Monitoring and Intrusion Detection: Implementing robust monitoring and intrusion detection systems can help detect suspicious activities associated with Dirty COW exploitation. This includes monitoring system logs, network traffic, and file integrity to identify signs of unauthorized access or file modifications.
  3. System Hardening: Implementing system hardening measures, such as minimizing unnecessary privileges, implementing access controls, and regularly auditing and updating system configurations, can help mitigate the risks associated with Dirty COW and other vulnerabilities.
  4. User Education: Educating users about the importance of keeping systems up to date, avoiding suspicious downloads, and practicing good cybersecurity hygiene is crucial in preventing and mitigating the risks associated with Dirty COW and other vulnerabilities.

Take away : The discovery of the Dirty COW vulnerability shed light on a critical flaw within the Linux kernel that exposed the potential for privilege escalation and compromise of Linux-based systems. The swift response from the Linux community in releasing patches and updates showcased the commitment to addressing the vulnerability. However, the incident emphasized the ongoing need for vigilant system administration practices, regular updates, and user education to combat evolving threats. Dirty COW served as a reminder of the ever-present risks in the cybersecurity landscape and the importance of proactive measures to safeguard critical systems and data.

Disclaimer : The information provided herein is on “as is” basis, without warranty of any kind.