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The wild part of DNS is that port 53 is typically open on firewalls and is excellent for data exfiltration/infiltration.
by mycall 1y ago
The wild part of DNS is that port 53 is typically open on firewalls and is excellent for data exfiltration/infiltration.
- nenenejej 1y agoIs it? Most firewalls I see allow no inbound by default (although all outbound)
- NegativeK 1y agoI assume they were referring to outbound. But ideally it'd be blocked and all traffic would go through an internal caching resolver, right? To reduce internal latency and load on outside servers, but also to have records if needed and to block whack requests or responses if needed.
- lormayna 1y agoIn a corporate environment you must use only the company DNS internal resolver and they are the only one that should go outside on port 53. This is a basic security measure to detect and block every attempt of DNS tunnelling or exfiltration
- tuwtuwtuwtuw 1y agoEven if you use the internal resolver you could exfiltrate the data.
- notepad0x90 1y agohighly detectable though. modern ngfw's are all over this.
- deoxykev 1y agoAnd it typically works on captive portals too before payment.
- Sophira 1y agoAFWall+ on Android is an example of this - even if an app is blocked, as long as it has Internet permission it can still make DNS requests, allowing for two-way communication despite the firewall.