Examples of Nested Encoding
Typically malicious scans use some sort of encoding to obscure their payloads. For example, instead of injecting a literal script, the attacker will run it through a PHP encoding function such as base64_encode(), utf8_encode(), or urlencode(). So if and when you need to decode some discovered payload, you can use whichever decoding function will do the job. For example, base64_decode(), utf8_decode(), or urldecode(). Sounds straightforward, but let’s dig a little deeper.. Continue reading »
Encoding & Decoding PHP Code
There are many ways to encode and decode PHP code. From the perspective of site security, there are three PHP functions — str_rot13(), base64_encode(), and gzinflate — that are frequently used to obfuscate malicious strings of PHP code. For those involved in the securing of websites, understanding how these functions are used to encode and decode encrypted chunks of PHP data is critical to accurate monitoring and expedient attack recovery. Continue reading »
Best Method for Email Obfuscation?
Awhile ago, Silvan Mühlemann conducted a 1.5 year experiment whereby different approaches to email obfuscation were tested for effectiveness. Nine different methods were implemented, with each test account receiving anywhere from 1800 to zero spam emails. Here is an excerpt from the article: When displaying an e-mail address on a website you obviously want to obfuscate it to avoid it getting harvested by spammers. But which obfuscation method is the best one? I drove a test to find out. After […] Continue reading »
URL Character Codes
URLs frequently employ potentially conflicting characters such as question marks, ampersands, and pound signs. Fortunately, it is possible to encode such characters via their escaped hexadecimal ASCII representations. For example, we would write ? as %3F. Here are a few more URL character codes (case-insensitive), for easy copy/paste reference. Continue reading »
