64 lines
5.0 KiB
Markdown
64 lines
5.0 KiB
Markdown
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
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- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
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- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
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- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
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- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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- **Share your hacking tricks by submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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On Linux, **tickets are stored in credential caches or ccaches**. There are 3 main types, which indicate where **tickets can be found:**
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* **Files**, by default under **/tmp** directory, in the form of **krb5cc\_%{uid}.**
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* **Kernel Keyrings**, an special space in the Linux kernel provided for storing keys.
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* **Process memory,** used when only one process needs to use the tickets.
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To verify what type of storage is used in a specific machine, the variable _**default\_ccache\_name**_** ** must be checked in the **/etc/krb5.conf** file, which by default has read permission to any user. In case of this parameter being missing, its default value is _FILE:/tmp/krb5cc\_%{uid}_.
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In order to extract **tickets from the other 2 sources** (keyrings and processes), a great paper, [**Kerberos Credential Thievery (GNU/Linux)**](https://www.delaat.net/rp/2016-2017/p97/report.pdf), released in 2017, explains ways of recovering the tickets from them.
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### Keyring - From the paper
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> The **Linux kernel** has a feature called **keyrings**. This is an **area of memory residing** within the kernel that is used to **manage and retain keys**.
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>
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> The **keyctl system call** was introduced in kernel version 2.6.10 5 . This provides **user space applications an API** which can be used to interact with kernel keyrings.
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> The **name of the keyring** in use can be parsed from the **Kerberos configuration file /etc/krb5.conf** which has read permission enable for anybody (octal 644) by default. An attacker can then leverage this information to **search for ticket** 11 containing keyrings and extract the tickets. A proof of concept script that implements this functionality can be seen in Section A.2 **(hercules.sh)**. In a keyring the ccache is stored as components. As seen in Figure 2, a file ccache is made up of 3 distinct components: header, default principal, and a sequence of credentials. A **keyring holds the default principal and credentials**. This script will dump these components to separate files. Then using an **attacker synthesised header** these pieces are combined in the correct order to **rebuild a file ccache**. This rebuilt file can then be exfiltrated to an attacker machine and then used to impersonate a Kerberos user. A simple program for generating a valid ccache header can be seen in Section A.3.
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Based on the **heracles.sh script** (from the paper) a C tool you can use (created by the author of the complete post) is [**tickey**](https://github.com/TarlogicSecurity/tickey)**, and it extracts tickets from keyrings:**
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```
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/tmp/tickey -i
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```
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**This information was taken from:** [**https://www.tarlogic.com/en/blog/how-to-attack-kerberos/**](https://www.tarlogic.com/en/blog/how-to-attack-kerberos/)
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<details>
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<summary><strong>Support HackTricks and get benefits!</strong></summary>
|
|
|
|
- Do you work in a **cybersecurity company**? Do you want to see your **company advertised in HackTricks**? or do you want to have access to the **latest version of the PEASS or download HackTricks in PDF**? Check the [**SUBSCRIPTION PLANS**](https://github.com/sponsors/carlospolop)!
|
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|
|
- Discover [**The PEASS Family**](https://opensea.io/collection/the-peass-family), our collection of exclusive [**NFTs**](https://opensea.io/collection/the-peass-family)
|
|
|
|
- Get the [**official PEASS & HackTricks swag**](https://peass.creator-spring.com)
|
|
|
|
- **Join the** [**💬**](https://emojipedia.org/speech-balloon/) [**Discord group**](https://discord.gg/hRep4RUj7f) or the [**telegram group**](https://t.me/peass) or **follow** me on **Twitter** [**🐦**](https://github.com/carlospolop/hacktricks/tree/7af18b62b3bdc423e11444677a6a73d4043511e9/\[https:/emojipedia.org/bird/README.md)[**@carlospolopm**](https://twitter.com/carlospolopm)**.**
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- **Share your hacking tricks by submitting PRs to the** [**hacktricks github repo**](https://github.com/carlospolop/hacktricks)**.**
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</details>
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