Application Protocol-Based Intrusion Detection System(APIDS)
A particular kind of security system called an Application Protocol-Based Intrusion Detection System (APIDS) is made to keep an eye on network activity at the OSI model’s application layer, or Layer 7.
An APIDS’s main objective is to identify and stop threats that target certain applications. An APIDS has the intelligence to comprehend the context, status, and permissible behaviour of particular application protocols like HTTP, SQL, FTP, DNS, or SMTP, in contrast to a more generic Network Intrusion Detection System (NIDS), which might concentrate on common network protocols like TCP/IP.
How an APIDS Works
The communication between an application and its services, such as between a web server and a SQL database, is usually monitored by APIDS.
- Protocol-Specific Monitoring: Rather than focussing only on general network traffic, APIDS is made to comprehend the particular guidelines and acceptable usage patterns of the application’s protocol.
- Data Gathering and Interpretation: It records application-level communication, such as SMTP messages or HTTP requests. It then maintains a thorough grasp of the syntax and semantics of the protocol (such as the SQL language) by parsing this data to interpret instructions and operations in accordance with the application protocol standards.
- Deep Packet Inspection (DPI): To find irregularities or protocol infractions, APIDS carries out DPI that is especially targeted at the application-level information and real content contained in the packets.
- Behaviour Analysis: It keeps track of client-server communications, examining parameters and data to make sure they adhere to the application’s and its protocol’s acceptable uses.
Detection Techniques
Two primary methods are employed by APIDS to detect intrusions:
- Signature-Based Detection: To find malicious activity, such a known SQL injection string, the collected traffic is compared to a database of known attack patterns or signatures.
- The first step in the anomaly-based detection technique is to create a baseline of typical application behaviour. Any action that substantially departs from this baseline, such as a user requesting an abnormally high volume of data or utilizing commands they have never used before, is then used to produce alerts.
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Attacks Detected
APIDS is particularly good at identifying threats that conventional lower-layer security tools might overlook since it focusses on application protocol abuse. The following are some instances of attacks that APIDS is intended to identify:
- When an attacker tries to alter a database by inserting malicious SQL code into an application’s input, this is known as SQL Injection (SQLi). APIDS monitors the SQL protocol to identify malicious SQL commands such as “OR 1=1.”
- When a hacker inserts dangerous scripts into websites that other people are seeing, this is known as cross-site scripting (XSS). APIDS keeps an eye out for malicious script tags in the HTTP protocol.
- Buffer Overflow Attacks: In order to overwrite memory and run malicious code, an attacker delivers more data than a buffer can contain. In order to identify input that is too lengthy, APIDS keeps an eye on data sizes and structure.
- Directory traversal is the process of keeping an eye out for sequences like../../ in a requested file path, which indicate an attempt to access restricted files, using protocols like HTTP or FTP.
Advantages of APIDS
By emphasising the integrity of the protocols themselves, APIDS provides an additional layer of security.
- Protocol Compliance: It detects any abuse and guarantees that network communications follow protocol guidelines to the letter.
- Focused Protection: APIDS offers more precise and in-depth information about possible threats by focussing on particular protocols rather than all network traffic.
- Deep Visibility: It is good at identifying sophisticated web-based attacks that could evade conventional NIDS since it provides deep visibility into application-level threats.
ModSecurity (commonly used for HTTP traffic), IronBee, and Bro/Zeek IDS are a few examples of APIDS.
However, the substantial processing overhead resulting from the deep inspection process which necessitates in-depth knowledge of every monitored protocol is a major drawback of APIDS.
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