Privilege Escalation by sudo cash - ties2/Red-Team GitHub Wiki

Another common technique used to escalate privileges on Unix-based systems is by exploiting the sudo caching mechanism. Sudo is a powerful tool used for managing permissions and access control on Unix-based systems. It allows users to run commands with elevated privileges, but only if they have been explicitly granted permission to do so. By default, sudo requires users to re-enter their password every time they want to run a command with elevated privileges. However, to make things more convenient for users, sudo has a caching mechanism that allows users to run multiple commands with elevated privileges without re-entering their password.

The sudo caching mechanism works by storing the user's password in memory for a set period of time after they have successfully authenticated with sudo. This means that if a user runs a command with elevated privileges using sudo, and then runs another command within the caching period, they will not be prompted for their password again. This can be convenient for users who need to run a series of commands that require elevated privileges.

However, this caching mechanism can also be exploited by attackers to escalate their privileges. If an attacker can gain access to a user's account, either by guessing their password or through a phishing attack, they can use the cached sudo credentials to run commands with elevated privileges without needing to know the user's password. This can give the attacker complete control over the system and allow them to install malware, steal data, or perform other malicious activities.

There are several ways that attackers can exploit the sudo caching mechanism. One common technique is to modify the system clock to trick sudo into thinking that the caching period has not expired. By setting the system clock back to the time when the user last authenticated with sudo, the attacker can make sudo think that the caching period is still valid, even if it has actually expired. This can allow the attacker to run commands with elevated privileges for an extended period of time without needing to re-enter the user's password.

Another technique is to use a tool like Mimikatz to extract the cached sudo credentials from memory. Mimikatz is a powerful tool used by attackers to extract plaintext passwords, hashes, and other sensitive information from memory on Windows and Unix-based systems. By using Mimikatz to extract the cached sudo credentials from memory, an attacker can use them to escalate their privileges without needing to know the user's password.

Exploiting the Sudo Cache Vulnerability

The sudo cache vulnerability can be exploited in several ways, including the following:

  • Exploiting an unsecured user account - Attackers can gain access to a user's account through social engineering, password cracking, or other means. Once the attacker has access to the user's account, they can execute a sudo command before the user's credentials expire from the cache. This gives the attacker root access to the system.

  • Using a compromised application - Attackers can also exploit the sudo cache vulnerability by compromising an application that runs with root privileges. Once the application is compromised, the attacker can use it to execute a sudo command, which will cache their credentials and give them root access to the system.

  • Using a Trojan horse - Attackers can also use a Trojan horse to exploit the sudo cache vulnerability. The Trojan horse is a malicious program that is disguised as a legitimate application. Once the Trojan horse is installed on the system, it can execute a sudo command, which will cache the attacker's credentials and give them root access to the system.

Preventing Sudo Caching Vulnerabilities

To prevent sudo caching vulnerabilities, there are several best practices that organizations can follow:

  • Disable sudo caching altogether:

While sudo caching can be convenient for users, it also increases the risk of privilege escalation attacks. To minimize this risk, organizations can disable sudo caching altogether, requiring users to re-enter their password every time they want to run a command with elevated privileges.

  • Set shorter caching periods:

If sudo caching is necessary for organizational workflows, administrators should set shorter caching periods to minimize the risk of exploitation. By setting shorter caching periods, organizations can reduce the window of opportunity for attackers to exploit cached credentials.

  • Monitor sudo usage:

Organizations should monitor sudo usage to detect any unusual activity or patterns. By monitoring sudo usage, administrators can detect and respond to privilege escalation attacks more quickly, before they can cause significant damage.

  • Use multifactor authentication:

Multifactor authentication can provide an additional layer of security, even if an attacker manages to obtain a user's password. By requiring a second factor, such as a biometric scan or a one-time code, organizations can significantly reduce the risk of privilege escalation attacks.

  • Keep systems up to date:

As with any security vulnerability, it is essential to keep systems up to date with the latest security patches and updates. By applying security updates as soon as they become available, organizations can minimize the risk of exploitation.

Conclusion

Privilege escalation attacks are a significant threat to the security of organizations and individuals.