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Admin Credential Abuse: How Darktrace Succeeded Where Other Solutions Failed

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17
Aug 2023
17
Aug 2023
This blog details a malicious actor’s attempt to abuse a customer’s administrative credentials in order to further their compromise on the network. Thanks to its anomaly-based approach to threat detection, Darktrace was the only solution in the customer’s stack to identify and contain the attack.

What is Admin Credential Abuse?

In an effort to remain undetected by increasingly vigilant security teams, malicious actors across the threat landscape often resort to techniques that allow them to remain ‘quiet’ on the network and carry out their objectives subtly. One such technique often employed by attackers is using highly privileged credentials to carry out malicious activity.

This emphasizes the need to be hyper vigilant and not assume that ‘administrative’ activity using privileged credentials is legitimate. In this way, both internal visibility and defense in-depth are needed, as well as a strong understanding of ‘normal’ administrative activity to then identify any deviations from this.  

In one recent example, Darktrace identified a threat actor attempting to use privileged administrative credentials to move laterally through a customer’s network and compromise two further critical servers. Darktrace DETECT™ identified that this activity was unusual and alerted the customer to early signs of compromise, reconnaissance and lateral movement to the other critical devices, while Darktrace RESPOND™ acted autonomously to inhibit the spread of activity and allowed the customer to quarantine the compromised devices.

Attack Overview and Darktrace Coverage

Over the course of a week in late May 2023, Darktrace observed a compromise on the network of a customer in the Netherlands. The threat actors primarily used living off the land techniques, abusing legitimate administrative credentials and executables to perform unexpected activities. This technique is intended to go under the radar of traditional security tools that are often unable to distinguish between the legitimate or malicious use of privileged credentials.

Darktrace was the only security solution in the customer’s stack that way able to detect and contain the attack, preventing it from spreading through their digital estate.

1. Device Reactivated

On May 22, 2023, Darktrace began to observe traffic originating from a File Server device which prior to this, had been been inactive on the network for some time, with no incoming or outgoing traffic recently observed for this IP. Therefore, upon initiating connections again, Darktrace’s AI tagged the device with the “Re-Activated Device” label. It also tagged the device as an “Internet Facing System”, which could represent an initial point of compromise.

Following this, the device was observed using an administrative credential that was commonly used across network, with no clear indications of brute-force activity or successive login failures preceeding this activity. The unusual use of a known credential on a network can be very difficult to detect for traditional security tools. Darktrace’s anomaly-based detection allows it to recognize subtle deviations in device behavior meaning it is uniquely placed to recognize this type of activity.

2. Reconaissance  

On the following day, the affected device began to perform SMB scans for open 445 ports, and writing files such as srvsvc and winreg, both of which are indicative of network  reconnaissance. Srvsvc is used to enumerate available SMB shares on destination devices which could be used to then write malicious files to these shares, while Winreg (Windows Registry) is used to store information that configures users, applications, and hardware devices [1]. Darktrace also observed the device carrying out DCE_RPC activity and making Windows Management Instrumentation (WMI) enumeration requests to other internal devices.

3. Lateral Movement via SMB

On May 24 and May 30, Darktrace observed the same device writing files over SMB to a number of other internal devices, including an SMB server and the Domain Controller. Darktrace identified that these writers were to privileged credential paths, such as C$ and ADMIN$, and it further recognized that the device was using the compromised administrative credential.

The files included remote command executable files (.exe) and batch scripts which execute commands upon clicking in a serial order. This behavior is indicative of a threat actor performing lateral movement in an attempt to infect other devices and strengthen their foothold in the network.

Files written:

·       LogConverter.bat

·       sql.bat

·       Microsoft.NodejsTools.PressAnyKey.exe

·       PSEXESVC.exe

·       Microsoft.NodejsTools.PressAnyKey.lnk

·       CG6oDkyFHl3R.t

5. Reconnaissance Spread

Around the same time as the observed lateral movement activity, between May 24 and May 30, the initially compromised device continued SMB and DCE_RPC activity, mainly involving SMB writes of files such as srvsvc, and PSEXESVC.exe.

Then, on May 28, Darktrace identified another internal Domain Controller engaging in similar suspicious behavior to the original compromised device. This included network scanning, enumeration and service control activity, indicating a spread of further malicious reconnaissance.

Following the successful detection of this activity, Darktrace’s Cyber AI Analyst launched autonomous investigations which was able to correlate incidents from multiple affected devices across the network, in doing so connecting multiple incidents into one security event.

Figure 1: Cyber AI Analyst connecting multiple events into one incident
Figure 2: Cyber AI Analyst investigation process to identify suspicious activity.

6. Lateral Movement

Alongside these SMB writes, the initially compromised device was seen connecting to various internal devices over ports associated with administrative protocols such as Remote Desktop Protocol (RDP). It also made a high volume of NTLM login failures for the credential ‘administrator’, suggesting that the malicious actor was attempting to brute-force an administrative credential.

7. Suspicious External Activity

Following earlier SMB writes from the initially compromised device to the Domain Controller server, the Domain Controller was seen making an unusual volume of external connections to rare endpoints which could indicate malicious command and control (C2) communication.

Alongside this activity, between May 30 and June 1, Darktrace also observed an unusually large number (over 12 million) of incoming connections from external endpoints. This activity is likely indicative of an attempted Denial of Service (DoS) attack.

Endpoints include:

·       45.15.145[.]92

·       198.2.200[.]89

·       162.211.180[.]215

Figure 3: Graphing function in the Darktrace UI showing the observed spike of inbound communication from external endpoints, indicating a potential DoS attack.

8. Reconnaissance and RDP activity

On May 31, the initially compromised device was seen creating an administrative RDP session with cookie ‘Administr’. Using the initially compromised administrative credential, further suspicious SMB activity was observed from the compromised devices on the same day including further SMB Enumeration, service control, PsExec remote command execution, and writes of another suspicious batch script file to various internal devices.

Darktrace RESPOND Coverage

Darktrace RESPOND’s autonomous response capabilities allowed it to take instantaneous preventative action against the affected devices as soon as suspicious activity was identified, consequently inhibiting the spread of this attack.

Specifically, Darktrace RESPOND was able to block suspicious connections to multiple internal devices and ports, among them port 445 which was used by threat actors to perform SMB scanning, for one hour. As a result of the autonomous actions carried out by Darktrace, the attack was stopped at the earliest possible stage.

Figure 4: Autonomous RESPOND actions taken against initially compromised devices.

In addition to these autonomous actions, the customer was able to further utilize RESPOND for containment purposes by manually actioning some of the more severe actions suggested by RESPOND, such as quarantining compromised devices from the rest of the network for a week.

Figure 5: Manually applied RESPOND actions to quarantine compromised devices for one week.

結論

As attackers continue to employ harder to detect living off the land techniques to exploit administrative credentials and move laterally across networks, it is paramount for organizations to have an intelligent decision maker that can recgonize the subtle deviations in device behavior.

Thanks to its Self-Learning AI, Darktrace is uniquely placed to understand its customer’s networks, allowing it to recognize unusual or uncommon activity for individual devices or user credentials, irrespective of whether this activity is typically considered as legitimate.

In this case, Darktrace was the only solution in the customer’s security stack that successfully identified and mitigated this attack. Darktrace DETECT was able to identify the the early stages of the compromise and provide full visibility over the kill chain. Meanwhile, Darktrace RESPOND moved at machine-speed, blocking suspicious connections and preventing the compromise from spreading across the customer’s network.

付録

Darktrace DETECT モデルブリーチ

Anomalous Connection / High Volume of New or Uncommon Service Control

Anomalous Connection / New or Uncommon Service Control

Anomalous Connection / SMB Enumeration

Anomalous Connection / Unusual Admin RDP Session

Anomalous Connection / Unusual Admin SMB Session

Anomalous File / Internal / Executable Uploaded to DC

Anomalous File / Internal / Unusual SMB Script Write

Anomalous Server Activity / Outgoing from Server

Anomalous Server Activity / Possible Denial of Service Activity

Antigena / Network / Insider Threat / Antigena Network Scan Block

Antigena / Network / Insider Threat / Antigena SMB Enumeration Block

Antigena / Network / Significant Anomaly / Antigena Enhanced Monitoring from Server Block

Antigena / Network / External Threat / Antigena File then New Outbound Block

Compliance / Outgoing NTLM Request from DC

Compliance / SMB Drive Write

Device / Anomalous NTLM Brute Force

Device / ICMP Address Scan  

Device / Internet Facing Device with High Priority Alert

Device / Large Number of Model Breaches

Device / Large Number of Model Breaches from Critical Network Device

Device / Multiple Lateral Movement Model Breaches

Device / Network Scan

Device / New or Uncommon SMB Named Pipe

Device / New or Uncommon WMI Activity

Device / New or Unusual Remote Command Execution

Device / Possible SMB/NTLM Brute Force

Device / RDP Scan

Device / SMB Lateral Movement

Device / SMB Session Brute Force (Admin)

Device / Suspicious SMB Scanning Activity

Darktrace RESPOND Model Breaches

Antigena / Network / Insider Threat / Antigena Network Scan Block

Antigena / Network / Insider Threat / Antigena SMB Enumeration Block

Antigena / Network / Significant Anomaly / Antigena Enhanced Monitoring from Server Block

Antigena / Network / External Threat / Antigena File then New Outbound Block

Cyber AI Analyst Incidents

Extensive Suspicious Remote WMI Activity

Extensive Unusual Administrative Connections

Large Volume of SMB Login Failures from Multiple Devices

Port Scanning

Scanning of Multiple Devices

SMB Writes of Suspicious Files

Suspicious Chain of Administrative Connections

Suspicious DCE_RPC Activity

TCP Scanning of Multiple Devices

MITRE ATT&CK マッピング

RECONNAISSANCE
T1595 Active Scanning
T1589.001 Gathering Credentials

CREDENTIAL ACCESS
T1110 Brute Force

LATERAL MOVEMENT
T1210 Exploitation of Remote Services
T1021.001 Remote Desktop Protocol

COMMAND AND CONTROL
T1071 Application Layer Protocol

IMPACT
T1498.001 Direct Network Flood

参考文献

[1] https://learn.microsoft.com/en-us/troubleshoot/windows-server/performance/windows-registry-advanced-users

INSIDE THE SOC
Darktrace cyber analysts are world-class experts in threat intelligence, threat hunting and incident response, and provide 24/7 SOC support to thousands of Darktrace customers around the globe. Inside the SOC is exclusively authored by these experts, providing analysis of cyber incidents and threat trends, based on real-world experience in the field.
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Zoe Tilsiter
Cyber Analyst
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Stemming the Citrix Bleed Vulnerability with Darktrace’s ActiveAI Platform

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28
May 2024

What is Citrix Bleed?

Since August 2023, cyber threat actors have been actively exploiting one of the most significant critical vulnerabilities disclosed in recent years: Citrix Bleed. Citrix Bleed, also known as CVE-2023-4966, remained undiscovered and even unpatched for several months, resulting in a wide range of security incidents across business and government sectors [1].

How does Citrix Bleed vulnerability work?

The vulnerability, which impacts the Citrix Netscaler Gateway and Netscaler ADC products, allows for outside parties to hijack legitimate user sessions, thereby bypassing password and multifactor authentication (MFA) requirements.

When used as a means of initial network access, the vulnerability has resulted in the exfiltration of sensitive data, as in the case of Xfinity, and even the deployment of ransomware variants including Lockbit [2]. Although Citrix has released a patch to address the vulnerability, slow patching procedures and the widespread use of these products has resulted in the continuing exploitation of Citrix Bleed into 2024 [3].

How Does Darktrace Handle Citrix Bleed?

Darktrace has demonstrated its proficiency in handling the exploitation of Citrix Bleed since it was disclosed back in 2023; its anomaly-based approach allows it to efficiently identify and inhibit post-exploitation activity as soon as it surfaces.  Rather than relying upon traditional rules and signatures, Darktrace’s Self-Learning AI enables it to understand the subtle deviations in a device’s behavior that would indicate an emerging compromise, thus allowing it to detect anomalous activity related to the exploitation of Citrix Bleed.

In late 2023, Darktrace identified an instance of Citrix Bleed exploitation on a customer network. As this customer had subscribed to the Proactive Threat Notification (PTN) service, the suspicious network activity surrounding the compromise was escalated to Darktrace’s Security Operation Center (SOC) for triage and investigation by Darktrace Analysts, who then alerted the customer’s security team to the incident.

Darktrace’s Coverage

Initial Access and Beaconing of Citrix Bleed

Darktrace’s initial detection of indicators of compromise (IoCs) associated with the exploitation of Citrix Bleed actually came a few days prior to the SOC alert, with unusual external connectivity observed from a critical server. The suspicious connection in question, a SSH connection to the rare external IP 168.100.9[.]137, lasted several hours and utilized the Windows PuTTY client. Darktrace also identified an additional suspicious IP, namely 45.134.26[.]2, attempting to contact the server. Both rare endpoints had been linked with the exploitation of the Citrix Bleed vulnerability by multiple open-source intelligence (OSINT) vendors [4] [5].

Darktrace model alert highlighting an affected device making an unusual SSH connection to 168.100.9[.]137 via port 22.
Figure 1: Darktrace model alert highlighting an affected device making an unusual SSH connection to 168.100.9[.]137 via port 22.

As Darktrace is designed to identify network-level anomalies, rather than monitor edge infrastructure, the initial exploitation via the typical HTTP buffer overflow associated with this vulnerability fell outside the scope of Darktrace’s visibility. However, the aforementioned suspicious connectivity likely constituted initial access and beaconing activity following the successful exploitation of Citrix Bleed.

Command and Control (C2) and Payload Download

Around the same time, Darktrace also detected other devices on the customer’s network conducting external connectivity to various endpoints associated with remote management and IT services, including Action1, ScreenConnect and Fixme IT. Additionally, Darktrace observed devices downloading suspicious executable files, including “tniwinagent.exe”, which is associated with the tool Total Network Inventory. While this tool is typically used for auditing and inventory management purposes, it could also be leveraged by attackers for the purpose of lateral movement.

防衛回避

In the days surrounding this compromise, Darktrace observed multiple devices engaging in potential defense evasion tactics using the ScreenConnect and Fixme IT services. Although ScreenConnect is a legitimate remote management tool, it has also been used by threat actors to carry out C2 communication [6]. ScreenConnect itself was the subject of a separate critical vulnerability which Darktrace investigated in early 2024. Meanwhile, CISA observed that domains associated with Fixme It (“fixme[.]it”) have been used by threat actors attempting to exploit the Citrix Bleed vulnerability [7].

Reconnaissance and Lateral Movement

A few days after the detection of the initial beaconing communication, Darktrace identified several devices on the customer’s network carrying out reconnaissance and lateral movement activity. This included SMB writes of “PSEXESVC.exe”, network scanning, DCE-RPC binds of numerous internal devices to IPC$ shares and the transfer of compromise-related tools. It was at this point that Darktrace’s Self-Learning AI deemed the activity to be likely indicative of an ongoing compromise and several Enhanced Monitoring models alerted, triggering the aforementioned PTNs and investigation by Darktrace’s SOC.

Darktrace observed a server on the network initiating a wide range of connections to more than 600 internal IPs across several critical ports, suggesting port scanning, as well as conducting unexpected DCE-RPC service control (svcctl) activity on multiple internal devices, amongst them domain controllers. Additionally, several binds to server service (srvsvc) and security account manager (samr) endpoints via IPC$ shares on destination devices were detected, indicating further reconnaissance activity. The querying of these endpoints was also observed through RPC commands to enumerate services running on the device, as well as Security Account Manager (SAM) accounts.  

Darktrace also identified devices performing SMB writes of the WinRAR data compression tool, in what likely represented preparation for the compression of data prior to data exfiltration. Further SMB file writes were observed around this time including PSEXESVC.exe, which was ultimately used by attackers to conduct remote code execution, and one device was observed making widespread failed NTLM authentication attempts on the network, indicating NTLM brute-forcing. Darktrace observed several devices using administrative credentials to carry out the above activity.

In addition to the transfer of tools and executables via SMB, Darktrace also identified numerous devices deleting files through SMB around this time. In one example, an MSI file associated with the patch management and remediation service, Action1, was deleted by an attacker. This legitimate security tool, if leveraged by attackers, could be used to uncover additional vulnerabilities on target networks.

A server on the customer’s network was also observed writing the file “m.exe” to multiple internal devices. OSINT investigation into the executable indicated that it could be a malicious tool used to prevent antivirus programs from launching or running on a network [8].

Impact and Data Exfiltration

Following the initial steps of the breach chain, Darktrace observed numerous devices on the customer’s network engaging in data exfiltration and impact events, resulting in additional PTN alerts and a SOC investigation into data egress. Specifically, two servers on the network proceeded to read and download large volumes of data via SMB from multiple internal devices over the course of a few hours. These hosts sent large outbound volumes of data to MEGA file storage sites using TLS/SSL over port 443. Darktrace also identified the use of additional file storage services during this exfiltration event, including 4sync, file[.]io, and easyupload[.]io. In total the threat actor exfiltrated over 8.5 GB of data from the customer’s network.

Darktrace Cyber AI Analyst investigation highlighting the details of a data exfiltration attempt.
Figure 2: Darktrace Cyber AI Analyst investigation highlighting the details of a data exfiltration attempt.

Finally, Darktrace detected a user account within the customer’s Software-as-a-Service (SaaS) environment conducting several suspicious Office365 and AzureAD actions from a rare IP for the network, including uncommon file reads, creations and the deletion of a large number of files.

Unfortunately for the customer in this case, Darktrace RESPOND™ was not enabled on the network and the post-exploitation activity was able to progress until the customer was made aware of the attack by Darktrace’s SOC team. Had RESPOND been active and configured in autonomous response mode at the time of the attack, it would have been able to promptly contain the post-exploitation activity by blocking external connections, shutting down any C2 activity and preventing the download of suspicious files, blocking incoming traffic, and enforcing a learned ‘pattern of life’ on offending devices.

結論

Given the widespread use of Netscaler Gateway and Netscaler ADC, Citrix Bleed remains an impactful and potentially disruptive vulnerability that will likely continue to affect organizations who fail to address affected assets. In this instance, Darktrace demonstrated its ability to track and inhibit malicious activity stemming from Citrix Bleed exploitation, enabling the customer to identify affected devices and enact their own remediation.

Darktrace’s anomaly-based approach to threat detection allows it to identify such post-exploitation activity resulting from the exploitation of a vulnerability, regardless of whether it is a known CVE or a zero-day threat. Unlike traditional security tools that rely on existing threat intelligence and rules and signatures, Darktrace’s ability to identify the subtle deviations in a compromised device’s behavior gives it a unique advantage when it comes to identifying emerging threats.

Credit to Vivek Rajan, Cyber Analyst, Adam Potter, Cyber Analyst

付録

Darktrace モデルカバレッジ

Device / Suspicious SMB Scanning Activity

Device / ICMP Address Scan

Device / Possible SMB/NTLM Reconnaissance

Device / Network Scan

Device / SMB Lateral Movement

Device / Possible SMB/NTLM Brute Force

Device / Suspicious Network Scan Activity

User / New Admin Credentials on Server

Anomalous File / Internal::Unusual Internal EXE File Transfer

Compliance / SMB Drive Write

Device / New or Unusual Remote Command Execution

Anomalous Connection / New or Uncommon Service Control

Anomalous Connection / Rare WinRM Incoming

Anomalous Connection / Unusual Admin SMB Session

Device / Unauthorised Device

User / New Admin Credentials on Server

Anomalous Server Activity / Outgoing from Server

Device / Long Agent Connection to New Endpoint

Anomalous Connection / Multiple Connections to New External TCP Port

Device / New or Uncommon SMB Named Pipe

Device / Multiple Lateral Movement Model Breaches

Device / Large Number of Model Breaches

Compliance / Remote Management Tool On Server

Device / Anomalous RDP Followed By Multiple Model Breaches

Device / SMB Session Brute Force (Admin)

Device / New User Agent

Compromise / Large Number of Suspicious Failed Connections

Unusual Activity / Unusual External Data Transfer

Unusual Activity / Enhanced Unusual External Data Transfer

Device / Increased External Connectivity

Unusual Activity / Unusual External Data to New Endpoints

Anomalous Connection / Data Sent to Rare Domain

Anomalous Connection / Uncommon 1 GiB Outbound

Anomalous Connection / Active Remote Desktop Tunnel

Anomalous Server Activity / Anomalous External Activity from Critical Network Device

Compliance / Possible Unencrypted Password File On Server

Anomalous Connection / Suspicious Read Write Ratio and Rare External

Device / Reverse DNS Sweep]

Unusual Activity / Possible RPC Recon Activity

Anomalous File / Internal::Executable Uploaded to DC

Compliance / SMB Version 1 Usage

Darktrace AI Analyst Incidents

Scanning of Multiple Devices

Suspicious Remote Service Control Activity

SMB Writes of Suspicious Files to Multiple Devices

Possible SSL Command and Control to Multiple Devices

Extensive Suspicious DCE-RPC Activity

Suspicious DCE-RPC Activity

Internal Downloads and External Uploads

Unusual External Data Transfer

Unusual External Data Transfer to Multiple Related Endpoints

MITRE ATT&CK マッピング

Technique – Tactic – ID – Sub technique of

Network Scanning – Reconnaissance - T1595 - T1595.002

Valid Accounts – Defense Evasion, Persistence, Privilege Escalation, Initial Access – T1078 – N/A

Remote Access Software – Command and Control – T1219 – N/A

Lateral Tool Transfer – Lateral Movement – T1570 – N/A

Data Transfers – Exfiltration – T1567 – T1567.002

Compressed Data – Exfiltration – T1030 – N/A

NTLM Brute Force – Brute Force – T1110 - T1110.001

AntiVirus Deflection – T1553 - NA

Ingress Tool Transfer   - COMMAND AND CONTROL - T1105 - NA

Indicators of Compromise (IoCs)

204.155.149[.]37 – IP – Possible Malicious Endpoint

199.80.53[.]177 – IP – Possible Malicious Endpoint

168.100.9[.]137 – IP – Malicious Endpoint

45.134.26[.]2 – IP – Malicious Endpoint

13.35.147[.]18 – IP – Likely Malicious Endpoint

13.248.193[.]251 – IP – Possible Malicious Endpoint

76.223.1[.]166 – IP – Possible Malicious Endpoint

179.60.147[.]10 – IP – Likely Malicious Endpoint

185.220.101[.]25 – IP – Likely Malicious Endpoint

141.255.167[.]250 – IP – Malicious Endpoint

106.71.177[.]68 – IP – Possible Malicious Endpoint

cat2.hbwrapper[.]com – Hostname – Likely Malicious Endpoint

aj1090[.]online – Hostname – Likely Malicious Endpoint

dc535[.]4sync[.]com – Hostname – Likely Malicious Endpoint

204.155.149[.]140 – IP - Likely Malicious Endpoint

204.155.149[.]132 – IP - Likely Malicious Endpoint

204.155.145[.]52 – IP - Likely Malicious Endpoint

204.155.145[.]49 – IP - Likely Malicious Endpoint

参考文献

  1. https://www.axios.com/2024/01/02/citrix-bleed-security-hacks-impact
  2. https://www.csoonline.com/article/1267774/hackers-steal-data-from-millions-of-xfinity-customers-via-citrix-bleed-vulnerability.html
  3. https://www.cybersecuritydive.com/news/citrixbleed-security-critical-vulnerability/702505/
  4. https://www.virustotal.com/gui/ip-address/168.100.9.137
  5. https://www.virustotal.com/gui/ip-address/45.134.26.2
  6. https://www.trendmicro.com/en_us/research/24/b/threat-actor-groups-including-black-basta-are-exploiting-recent-.html
  7. https://www.cisa.gov/news-events/cybersecurity-advisories/aa23-325a
  8. https://www.file.net/process/m.exe.html
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著者について
Vivek Rajan
Cyber Analyst

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Eメール

How to Protect your Organization Against Microsoft Teams Phishing Attacks

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21
May 2024

The problem: Microsoft Teams phishing attacks are on the rise

Around 83% of Fortune 500 companies rely on Microsoft Office products and services1, with Microsoft Teams and Microsoft SharePoint in particular emerging as critical platforms to the business operations of the everyday workplace. Researchers across the threat landscape have begun to observe these legitimate services being leveraged more and more by malicious actors as an initial access method.

As Teams becomes a more prominent feature of the workplace many employees rely on it for daily internal and external communication, even surpassing email usage in some organizations. As Microsoft2 states, "Teams changes your relationship with email. When your whole group is working in Teams, it means you'll all get fewer emails. And you'll spend less time in your inbox, because you'll use Teams for more of your conversations."

However, Teams can be exploited to send targeted phishing messages to individuals either internally or externally, while appearing legitimate and safe. Users might receive an external message request from a Teams account claiming to be an IT support service or otherwise affiliated with the organization. Once a user has accepted, the threat actor can launch a social engineering campaign or deliver a malicious payload. As a primarily internal tool there is naturally less training and security awareness around Teams – due to the nature of the channel it is assumed to be a trusted source, meaning that social engineering is already one step ahead.

Screenshot of a Microsoft Teams message request from a Midnight Blizzard-controlled account (courtesy of Microsoft)
Figure 1: Screenshot of a Microsoft Teams message request from a Midnight Blizzard-controlled account (courtesy of Microsoft)

Microsoft Teams Phishing Examples

Microsoft has identified several major phishing attacks using Teams within the past year.

In July 2023, Microsoft announced that the threat actor known as Midnight Blizzard – identified by the United States as a Russian state-sponsored group – had launched a series of phishing campaigns via Teams with the aim of stealing user credentials. These attacks used previously compromised Microsoft 365 accounts and set up new domain names that impersonated legitimate IT support organizations. The threat actors then used social engineering tactics to trick targeted users into sharing their credentials via Teams, enabling them to access sensitive data.  

At a similar time, threat actor Storm-0324 was observed sending phishing lures via Teams containing links to malicious SharePoint-hosted files. The group targeted organizations that allow Teams users to interact and share files externally. Storm-0324’s goal is to gain initial access to hand over to other threat actors to pursue more dangerous follow-on attacks like ransomware.

Darktrace がMicrosoft Teamsのフィッシングを阻止する方法について、さらに詳しく知りたい方は、ブログをお読みください: 餌に喰いつくな:Darktrace Microsoft Teamsのフィッシング攻撃を阻止する方法

The market: Existing Microsoft Teams security solutions are insufficient

Microsoft’s native Teams security focuses on payloads, namely links and attachments, as the principal malicious component of any phishing. These payloads are relatively straightforward to detect with their experience in anti-virus, sandboxing, and IOCs. However, this approach is unable to intervene before the stage at which payloads are delivered, before the user even gets the chance to accept or deny an external message request. At the same time, it risks missing more subtle threats that don’t include attachments or links – like early stage phishing, which is pure social engineering – or completely new payloads.

Equally, the market offering for Teams security is limited. Security solutions available on the market are always payload-focused, rather than taking into account the content and context in which a link or attachment is sent. Answering questions like:

  • Does it make sense for these two accounts to speak to each other?
  • Are there any linguistic indicators of inducement?

Furthermore, they do not correlate with email to track threats across multiple communication environments which could signal a wider campaign. Effectively, other market solutions aren’t adding extra value – they are protecting against the same types of threats that Microsoft is already covering by default.

The other aspect of Teams security that native and market solutions fail to address is the account itself. As well as focusing on Teams threats, it’s important to analyze messages to understand the normal mode of communication for a user, and spot when a user’s Teams activity might signal account takeover.

The solution: How Darktrace protects Microsoft Teams against sophisticated threats

With its biggest update to Darktrace/Email ever, Darktrace now offers support for Microsoft Teams. With that, we are bringing the same AI philosophy that protects your email and accounts to your messaging environment.  

Our Self-Learning AI looks at content and context for every communication, whether that’s sent in an email or Teams message. It looks at actual user behavior, including language patterns, relationship history of sender and recipient, tone and payloads, to understand if a message poses a threat. This approach allows Darktrace to detect threats such as social engineering and payloadless attacks using visibility and forensic capabilities that Microsoft security doesn’t currently offer, as well as early symptoms of account compromise.  

Unlike market solutions, Darktrace doesn’t offer a siloed approach to Teams security. Data and signals from Teams are shared across email to inform detection, and also with the wider Darktrace ActiveAI security platform. By correlating information from email and Teams with network and apps security, Darktrace is able to better identify suspicious Teams activity and vice versa.  

Interested in the other ways Darktrace/Email augments threat detection? Read our latest blog on how improving the quality of end-user reporting can decrease the burden on the SOC. To find our more about Darktrace's enduring partnership with Microsoft, click here.

参考文献

[1] Essential Microsoft Office Statistics in 2024

[2] Microsoft blog, Microsoft Teams and email, living in harmony, 2024

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Carlos Gray
Product Manager
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