Trustwave SpiderLabs Uncovers Critical Cybersecurity Vulnerabilities Exposing Manufacturers to Costly Attacks. Learn More

Trustwave SpiderLabs Uncovers Critical Cybersecurity Vulnerabilities Exposing Manufacturers to Costly Attacks. Learn More

Services
Capture
Managed Detection & Response

Eradicate cyberthreats with world-class intel and expertise

twi-cloud-lock-color-svg
Managed Security Services

Expand your team’s capabilities and strengthen your security posture

twi-briefcase-color-svg
Consulting & Professional Services

Tap into our global team of tenured cybersecurity specialists

twi-dashboard-color-svg
Penetration Testing

Subscription- or project-based testing, delivered by global experts

twi-database-color-svg
Database Security

Get ahead of database risk, protect data and exceed compliance requirements

twi-email-color-svg
Email Security & Management

Catch email threats others miss with layered security & maximum control

twi-managed-portal-color
Co-Managed SOC (SIEM)

Eliminate alert fatigue, focus your SecOps team, stop threats fast, and reduce cyber risk

Solutions
BY TOPIC
Microsoft Exchange Server Attacks
Stay protected against emerging threats
Rapidly Secure New Environments
Security for rapid response situations
Securing the Cloud
Safely navigate and stay protected
Securing the IoT Landscape
Test, monitor and secure network objects
Why Trustwave
The Trustwave Approach
Awards and Accolades
Trustwave SpiderLabs Team
Trustwave Fusion Platform
SpiderLabs Fusion Center
Security Operations Centers
Partners
Technology Alliance Partners
Key alliances who align and support our ecosystem of security offerings
Trustwave PartnerOne Program
Join forces with Trustwave to protect against the most advance cybersecurity threats
SpiderLabs Blog

Network Detection for ZeroLogon CVE-2020-1472

ZeroLogon has quickly become popular and well known because of multiple proofs of concept and exploits implemented in Python, .NET, Powershell, and Mimikatz implemented a module for it. So if you are an attacker or need to test your environment then you have plenty of options. As defenders, we also have options for detection on the network. If you aren’t familiar with ZeroLogon and need a quick overview then please check out our ZeroLogon Blog.

When looking at the PoC code and corresponding network traffic, some elements standout that can be used for detection. One of the most glaring is the repeated NetrServerReqChallenge and NetrServerAuthenticate requests and responses.

Image001

Within the NetrServerAuthenticate request, you may want to create detections based on the DCE_RPC version, packet flags, and certainly the Opnum. Also, in the NetrServerAuthenticate section, the Client Credential may be visible as well as the Negotiation Options. Detection within NetrServerAuthenticate isn’t always possible as shown below. This section can and should be encrypted.

Image002

Image003

According to Secura’s report, it takes an average of 256 attempts to exploit. So looking for many NetrServerReqChallenge and NetrServerAuthenticate requests/responses and ending with a NetrServerPasswordSet request/response, can be useful for network detection. Though I have seen some reports on the attack working with much lower attempt numbers.

There is another detection mechanism that can be useful for detecting post exploit activity. If the password is changed for the domain controller itself, it creates errors within the network. According to Secura’s report, this is due to password discrepancies between active directory and registry. I noticed that once the DC’s password was modified I started getting KRB5KRB_AP_ERR_MODIFIED errors. This can be another mechanism for detection within the network, especially if the errors are coming from multiple clients.

Image004

Summary

In summary, there are two primary methods that can be used to identify the potential exploitation of Zerologon. Monitoring for a large number of NetrServerReqChallenge and NetrServerAuthenticate in a short period of time will identify attempts to force a ClientCredential to all zeros. The interval may vary depending on the network but it only takes about 3 seconds to complete the exploit. The threshold may need to be adjusted in the network to account for potential false positives or as the exploits become more mature but starting around 5-10 seconds should be safe. For more specific alerts that trigger on the full exploitation chain, you should monitor for where you see a large number of the Challenge/Authenticate which are followed by a NetrServerPasswordSet request/response.

Additionally, you can monitor for post-exploitation activity via Kerberos certificate errors that indicate that the server password has been modified.

As time goes on attacks will evolve and so will the detection mechanisms. For now, these network indicators can be a useful tool to add to your arsenal. Trustwave customers using our IDPS devices or ruleset service will find protection against exploits targeting this vulnerability.

Latest SpiderLabs Blogs

Trustwave SpiderLabs Report: LockBit 3.0 Ransomware Vs. the Manufacturing Sector

As the manufacturing sector continues its digital transformation, Operational Technology (OT), Industrial Control Systems (ICS), and Supervisory Control and Data Acquisition (SCADA) are becoming...

Read More

Overview of the Cyberwarfare used in Israel – Hamas War

On October 7, 2023, the Palestinian organization Hamas launched the biggest attack on Israel in years, resulting in numerous casualties and hostages taken. Israel responded with a large-scale ground...

Read More

The 2023 Retail Services Sector Threat Landscape: A Trustwave Threat Intelligence Briefing

The annual holiday shopping season is poised for a surge in spending, a fact well-known to retailers, consumers, and cybercriminals alike. The latter group, however, is poised to exploit any...

Read More