Initial Access 🔓

• Goal: The attacker gains initial access to the target system.

• Initial Access Techniques

  • 📥 Content Injection

  • 🌐 Exploit Public-Facing Application

  • 🛠 Hardware Additions

  • 💾 Replication Through Removable Media

  • 🤝 Trusted Relationship

  • 🚗 Drive-by Compromise

  • 🌍 External Remote Services

  • 🎣 Phishing

  • 🔗 Supply Chain Compromise

  • 🔑 Valid Accounts

Content Injection Attack: Threats and Defense Strategies

What is a Content Injection Attack?

A Content Injection Attack is a cyberattack where adversaries manipulate legitimate online network traffic to inject malicious content into a target system.

Unlike traditional drive-by download attacks, where victims are lured to malicious websites, content injection attacks directly alter existing legitimate network traffic to insert a malicious payload.

Through this method, adversaries can:
✔ Gain initial access to a system.
✔ Deliver additional malware to the target.
✔ Exfiltrate data or maintain persistence on an already compromised system.

Types of Content Injection Attacks

Adversaries manipulate network traffic in two primary ways:

1. From the Middle

• Attackers intercept legitimate client-server communication and modify the response before delivering it to the victim.

• Similar to an Adversary-in-the-Middle (AiTM) attack, but broader in scope, often targeting entire ISP networks.

✔ Example:

• An attacker hijacks a user’s connection to a legitimate website and injects a malicious script into the response.

• On unencrypted HTTP sites, attackers alter network traffic to redirect users to malicious versions of intended content.

2. From the Side

• Attackers observe legitimate requests and race to deliver a fake response first before the legitimate server can reply.

✔ Example:

• When a user attempts to download a software update, the attacker intercepts the request and delivers a malware-laced update instead.

• Attackers use packet injection techniques to deliver fake data before the legitimate data reaches the victim.

ISP-Level Content Injection

In more sophisticated cases, adversaries may compromise network infrastructure, including Internet Service Providers (ISPs) or government-controlled networks, to manipulate online traffic.

✔ Example:

• Attackers modify ISP-level traffic to inject malicious advertisements or redirect users to phishing pages.

• Governments or state-sponsored actors may intercept and alter user traffic for mass surveillance or targeted attacks.

• Public Wi-Fi networks (e.g., in airports, hotels, or cafes) may be exploited to deliver malicious payloads to unsuspecting users.

Risks and Impact of Content Injection

✔ Stealthy and difficult to detect

• Unlike traditional malware delivery methods, victims do not intentionally visit a malicious site, making detection more challenging.

• Lack of HTTPS encryption makes traffic manipulation easier.

✔ Impacts individuals, corporations, and infrastructure

• ISP-level manipulation can compromise entire corporate networks or even national infrastructure.

• Software updates, financial transactions, and cloud services are prime targets.

✔ Used for malware distribution, credential theft, and supply chain attacks

• Adversaries use content injection to deliver malware, steal login credentials, or infiltrate enterprise networks.

Mitigation Strategies

✔ Enforce HTTPS and certificate validation

• Websites should encrypt all traffic using SSL/TLS and implement strict certificate validation to prevent interception.

✔ Implement DNS security (DNSSEC)

• Prevent DNS hijacking and redirection to malicious sites by enabling DNSSEC (DNS Security Extensions).

✔ Adopt Zero Trust network security

• Continuously monitor internal and external network traffic for anomalies and suspicious activities.

✔ Use VPNs and secure DNS services

• Users should utilize trusted VPNs and secure DNS providers (e.g., Cloudflare 1.1.1.1 or Google Public DNS) when accessing the internet in untrusted environments.

Content Injection Attack: Mitigation and Detection Strategies

Mitigations (완화 방법)

M1041 - Encrypt Sensitive Information
Ensure that online traffic is appropriately encrypted through services such as trusted VPNs. (온라인 트래픽이 신뢰할 수 있는 VPN과 같은 서비스로 적절하게 암호화되도록 보장해야 한다.)

M1021 - Restrict Web-Based Content
Consider blocking download/transfer and execution of potentially uncommon file types known to be used in adversary campaigns. (공격자가 사용하는 것으로 알려진 비정상적인 파일 유형의 다운로드, 전송, 실행을 차단하는 것을 고려해야 한다.)

Detection (탐지 방법)

DS0022 - File Creation
Monitor for unexpected and abnormal file creations that may indicate malicious content injected through online network communications. (온라인 네트워크 통신을 통해 악성 콘텐츠가 주입되었을 가능성이 있는 예상치 못한 파일 생성 여부를 모니터링해야 한다.)

DS0029 - Network Traffic Content
Monitor for other unusual network traffic that may indicate additional malicious content transferred to the system. Use network intrusion detection systems, sometimes with SSL/TLS inspection, to look for known malicious payloads, content obfuscation, and exploit code.
(추가적인 악성 콘텐츠가 시스템으로 전송되었을 가능성을 나타낼 수 있는 비정상적인 네트워크 트래픽을 모니터링해야 한다. 네트워크 침입 탐지 시스템(NIDS)을 활용하고, 경우에 따라 SSL/TLS 검사를 사용하여 악성 페이로드, 콘텐츠 난독화, 익스플로잇 코드가 포함된 트래픽을 탐지할 수 있다.)

DS0009 - Process Creation
Look for behaviors on the endpoint system that might indicate successful compromise, such as abnormal behaviors of browser processes. This could include suspicious files written to disk, evidence of Process Injection for attempts to hide execution, or evidence of Discovery.
(엔드포인트 시스템에서 침해 가능성을 나타낼 수 있는 행동을 감지해야 한다. 예를 들어, 브라우저 프로세스의 비정상적인 동작을 살펴보고, 디스크에 의심스러운 파일이 기록되었는지, 실행을 숨기려는 프로세스 인젝션(Process Injection)의 흔적이 있는지, 시스템 정보 수집(Discovery)의 증거가 있는지를 확인해야 한다.)