Perfectly Coded APIs Can Be Susceptible To Attack

An Application Programming Interface (API) is a way for two or more computer programmes to communicate with each other - a type of software that offers a service to other pieces of software. API development has seen an over emphasis on ‘shift left’, whereby security testing, quality and performance are carried out solely in the development process rather than throughout the entire release cycle.  

While this has allowed departments to develop and roll out their own “secure” APIs, it assumes that the developer is happy to ‘mark their own homework’ and fix the code when many hate this aspect of the job. 

But there’s another more serious danger in that it creates a false sense of security. The assumption is that APIs that go live are then bullet proof.

In reality, while shift left efforts are beneficial, no measures will stop a persistent automated attack. If the assets being protected by that API are attractive enough, attackers will persist and will compromise it usually by using its own functionality against it in an attack known as business logic abuse.

Even if the API is coded perfectly correctly, adheres to the API specification it is designed against, and is properly inventoried and has been tested to ensure it is not susceptible to any of the OWASP (Open Web Application Security Project) Top Ten API Threats, it can still be probed and compromised. 

Research conducted during the first half of 2022 reveals that APIs were subjected to automated business logic abuse in numerous ways. Over three billion shopping bots were used to target well-formed APIs with a dense network of highly volumetric and geographically distributed fuzzing payloads. Over 290 million malicious gift card requests used enumeration based on fuzzing the numeric patterns on APIs that support payment and checkout microservices. And there were over 37 million comment spam requests detected against customer relationship management workflows.

Combined Assaults

Perfectly coded and inventoried APIs take more effort to compromise and so attacks will typically use multiple methods from the OWASP Top Ten. For instance, we’ve seen something we call the attack trifecta where attackers used API2 (Broken User Authentication), API3 (Excessive Data Exposure) and API9 (Improper Assets management), to perform detailed reconnaissance and analysis of how each API works, how they interact with each other, and the expected outcome. That information was then used for malicious purposes. 

Another real-world example is the Ulta Beauty case study where a large scale enumeration attack was executed against a third party inventory API. The inventory search API supplier notified the company security team of a traffic surge, requesting help to stop the attack. The investigation mapped the attack to OWASP API4 (Lack of Resources and Rate Limiting) and API5 (Broken Function Level Authorisation). 

Initially, the attackers targeted the web API before moving to the mobile API which provides similar information. The attack targeted the inventory API directly, without hitting any other app or web function (in contrast, normal behaviour would show the user traversing multiple APIs, generating upwards of 40-50 cookies as they browsed the inventory, whereas the attack generated just one). 

Originating from residential proxy IP addresses, the attack rotated through 153,000 unique product and SKU combinations while scraping 61,000 ZIP codes and 33,000 products but Web Application Firewall (WAF) and Content Delivery Network (CDN) mitigation efforts were ineffective. It was only stopped by policies that effectively blocked 85.9 million requests.

The Difficulty Of Detection 

In this particular case the company was alerted by its provider but how can businesses spot attacks against what they consider to be secure APIs? Web Application Firewalls (WAFs) or bot prevention tools are ineffective at preventing an API specific attack for several reasons. 

WAFs use signatures to detect known vulnerabilities as described in the OWASP Web Application Top 10 Threats list so will struggle to find and block attacks that appear legitimate, and they are unable to address the entire API protection lifecycle. Bot tools rely on JavaScript instrumentation to collect the telemetry required to understand and block the attack. As an API is clientless, it cannot be instrumented in this manner. Consequently, those that believe their APIs are secure and rely on traditional web security tools are lulled into a false sense of security.

The first step in any API protection initiative should always be a runtime inventory. This automatically logs all known and unknown endpoints, helping to discover and prioritise APIs by assessing the risk they represent, and applying sensitive data exposure protection and business logic abuse protection. The next step is to protect the APIs from attacks  using Machine Learning to determine the intent of transactions (whether performed by bots or individuals) and then quickly block them or send them down another path. 

With runtime security covered, development teams should look at more API specific testing solutions to complement and strengthen existing shift left efforts. Dynamic Application Security Testing (DAST) solutions that use specifications and documentation to understand how an API works, then looks for vulnerabilities should also be considered. Traditional web-focused testing tools lack the ability to derive the API context needed to test and find gaps and this is where DAST can really add value.  

There also needs to be acceptance that, while shift left is helping organisations deliver more secure APIs, even a perfectly coded API can be attacked. The OWASP Top Ten lists are useful, but should be viewed as a starting point.

Until we face up to the fact that all APIs will fall to a determined attacker, we can’t begin to adequately protect them.   

Andy Mills is VP for EMEA at Cequence Security

You Might Also Read: 

Types Of Security Testing Explained With Examples:

___________________________________________________________________________________________

If you like this website and use the comprehensive 6,500-plus service supplier Directory, you can get unrestricted access, including the exclusive in-depth Directors Report series, by signing up for a Premium Subscription.

  • Individual £5 per month or £50 per year. Sign Up
  • Multi-User, Corporate & Library Accounts Available on Request

Cyber Security Intelligence: Captured Organised & Accessible


 

« Europol Arrest Crypto Currency Fraud Gang
Sexual Abuse & Harassment Of Women »

CyberSecurity Jobsite
Perimeter 81

Directory of Suppliers

MIRACL

MIRACL

MIRACL provides the world’s only single step Multi-Factor Authentication (MFA) which can replace passwords on 100% of mobiles, desktops or even Smart TVs.

Authentic8

Authentic8

Authentic8 transforms how organizations secure and control the use of the web with Silo, its patented cloud browser.

ZenGRC

ZenGRC

ZenGRC (formerly Reciprocity) is a leader in the GRC SaaS landscape, offering robust and intuitive products designed to make compliance straightforward and efficient.

NordLayer

NordLayer

NordLayer is an adaptive network access security solution for modern businesses — from the world’s most trusted cybersecurity brand, Nord Security. 

DigitalStakeout

DigitalStakeout

DigitalStakeout enables cyber security professionals to reduce cyber risk to their organization with proactive security solutions, providing immediate improvement in security posture and ROI.

Montash

Montash

Montash is an award winning, global technology recruitment business, specialising in the acquisitions of high-performing talent across a number of core disciplines including Information Security.

AppRiver

AppRiver

AppRiver is a global provider of cloud-based email and web security solutions that protect businesses worldwide from today's ever-changing online threats.

Bloombase

Bloombase

Bloombase is the leading innovator in Next-Generation Data Security solutions for Global 2000-scale organizations

Crypto4A Technologies

Crypto4A Technologies

Crypto4A quantum-ready cybersecurity solutions significantly improve protection for Cloud, loT, Blockchain, V2X, government and military application deployments.

TES

TES

TES is a provider of IT Lifecycle Services, offering bespoke solutions that help customers manage the commissioning, deployment and retirement of Information Technology assets.

Security BSides

Security BSides

Security BSides is the first grass roots, DIY, open security conference in the world!. BSides is a community-driven framework for building events for and by information security community members.

ColorTokens

ColorTokens

ColorTokens Xtended ZeroTrust Platform protects from the inside out with unified visibility, micro-segmentation, zero-trust network access, cloud workload and endpoint protection.

AUTOCRYPT

AUTOCRYPT

AUTOCRYPT is a mobility security provider dedicated to the safety of future transportation

Cyber Skyline

Cyber Skyline

Cyber Skyline is a revolutionary cloud platform to practice, develop, and measure your team's technical cybersecurity skills.

HiScout

HiScout

HiScout is your integrated management system for IT governance, risk & compliance.

Scholarly Networks Security Initiative (SNSI)

Scholarly Networks Security Initiative (SNSI)

SNSI brings together publishers and institutions to solve cyber-challenges threatening the integrity of the scientific record, scholarly systems and the safety of personal data.

SecOps Group

SecOps Group

SecOps Group is a boutique cybersecurity consultancy helping enterprises identify & eliminate security risks on a continuous basis.

BitLyft

BitLyft

BitLyft is a managed detection and response provider that is dedicated to delivering unparalleled protection from cyber attacks for organizations of all sizes.

Odaseva

Odaseva

Odaseva delivers the strongest data security solution for enterprises running on Salesforce, safeguarding confidentiality and integrity of critical business information.

Sattrix Information Security

Sattrix Information Security

Sattrix Information Security understand the evolving threat landscape and provide businesses with comprehensive cybersecurity solutions.

Hexagate

Hexagate

Hexagate is at the forefront of blockchain threat prevention and automated risk management, proactively detecting and mitigating threats to smart contracts and onchain assets.