July 26, 2022

Self-Learning AI for Zero-Day and N-Day Attack Defense

Explore the differences between zero-day and n-day attacks on different customer servers to learn how Darktrace detects and prevents cyber threats effectively.

Written by

Lewis Morgan

Cyber Analyst

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.

Written by

Lewis Morgan

Cyber Analyst

Jul 2022

‍Key Terms:

Zero-day | A recently discovered security vulnerability in computer software that has no currently available fix or patch. Its name come from the reality that vendors have “zero days” to act and respond.

N-day | A vulnerability that emerges in computer software in which a vendor is aware and may have already issued (or are currently working on) a patch or fix. Active exploits often already exist and await abuse by nefarious actors.

Traditional security solutions often apply signature-based-detection when identifying cyber threats, helping to defend against legacy attacks but consequently missing novel ones. Therefore, security teams often lend a lot of focus to ensuring that the risk of zero-day vulnerabilities is reduced [1]. As explored in this blog, however, organizations can face just as much of a risk from n-day attacks, since they invite the most attention from malicious actors [2]. This is due in part to the reduced complexity, cost and time invested in researching and finding new exploits compared with that found when attackers exploit zero-days.

This blog will examine both a zero-day and n-day attack that two different Darktrace customers faced in the fall of 2021. This will include the activity Darktrace detected, along with the steps taken by Darktrace/Network to intervene. It will then compare the incidents, discuss the possible dangers of third-party integrations, and assess the deprecation of legacy security tools.

Revisiting zero-day attacks

Zero-days are among the greatest concerns security teams face in the era of modern technology and networking. Defending critical systems from zero-day compromises is a task most legacy security solutions are often unable to handle. Due to the complexity of uncovering new security flaws and developing elaborate code that can exploit them, these attacks are often carried out by funded or experienced groups such as nation-state actors and APTs. One of history’s most prolific zero-days, ‘Stuxnet’, sent security teams worldwide into a global panic in 2010. This involved a widespread attack on Iranian nuclear infrastructure and was widely accepted to be a result of nation-state actors [3]. The Stuxnet worm took advantage of four zero-day exploits, compromising over 200,000 devices and physically damaging around 10% of the 9,000 critical centrifuges at the Natanz nuclear site.

More recently, 2021 saw the emergence of several critical zero-day vulnerabilities within SonicWall’s product suite [4]. SonicWall is a security hardware manufacturer that provides hardware firewall devices, unified threat management, VPN gateways and network security solutions. Some of these vulnerabilities lie within their Secure Mobile Access (SMA) 100 series (for example, CVE-2019-7481, CVE-2021-20016 and CVE-2021-20038 to name a few). These directly affected VPN devices and often allowed attackers easy remote access to company devices. CVE-2021-20016 in particular incorporates an SQL-Injection vulnerability within SonicWall’s SSL VPN SMA 100 product line [5]. If exploited, this defect would allow an unauthenticated remote attacker to perform their own malicious SQL query in order to access usernames, passwords and other session related information.

The N-day underdog

The shadow cast by zero-day attacks often shrouds that of n-day attacks. N-days, however, often pose an equal - if not greater - risk to the majority of organizations, particularly those in industrial sectors. Since these vulnerabilities have fixes available, all of the hard work around research is already done; malicious actors only need to view proof of concepts (POCs) or, if proficient in coding, reverse-engineer software to reveal code-changes (binary diffing) in order to exploit these security flaws in the wild. These vulnerabilities are typically attributed to opportunistic hackers and script-kiddies, where little research or heavy lifting is required.

August 2021 gave rise to a critical vulnerability in Atlassian Confluence servers, namely CVE-2021-26084 [6]. Confluence is a widely used collaboration wiki tool and knowledge-sharing platform. As introduced and discussed a few months ago in a previous Darktrace blog (Explore Internet-Facing System Vulnerabilities), this vulnerability allows attackers to remotely execute code on internet-facing servers after exploiting injection vulnerabilities in Object-Graph Navigation Language (OGNL). Whilst Confluence had patches and fixes available to users, attackers still jumped on this opportunity and began scanning the internet for signs of critical devices serving this outdated software [7]. Once identified, they would exploit the vulnerability, often installing crypto mining software onto the device. More recently, Darktrace explored a new vulnerability (CVE-2022-26134), disclosed midway through 2022, that affected Confluence servers and data centers using similar techniques to that found in CVE-2021-26084 [8].

SonicWall in the wild – 1. Zero-day attack

At the beginning of August 2021, Darktrace prevented an attack from taking place within a European automotive customer’s environment (Figure 1). The attack targeted a vulnerable internet-facing SonicWall VPN server, and while the attacker’s motive remains unclear, similar historic events suggest that they intended to perform ransomware encryption or data exfiltration.

Figure 1: Timeline of the SonicWall attack

Darktrace was unable to confirm the definite tactics, techniques and procedures (TTPs) used by the attacker to compromise the customer’s environment, as the device was compromised before Darktrace installation and coverage. However, from looking at recently disclosed SonicWall VPN vulnerabilities and patterns of behaviour, it is likely CVE-2021-20016 played a part. At some point after this initial infection, it is also believed the device was able to move laterally to a domain controller (DC) using administrative credentials; it was this server that then initiated the anomalous activity that Darktrace detected and alerted on.

On August 5^th 2021 , Darktrace observed this compromised domain controller engaging in unusual ICMP scanning - a protocol used to discover active devices within an environment and create a map of an organization’s network topology. Shortly after, the infected server began scanning devices for open RDP ports and enumerating SMB shares using unorthodox methods. SMB delete and HTTP requests (over port 445 and 80 respectively) were made for files named delete.me in the root directory of numerous network shares using the user agent Microsoft WebDAV. However, no such files appeared to exist within the environment. This may have been the result of an attacker probing devices in the network in an effort to see their responses and gather information on properties and vulnerabilities they could later exploit.

Soon the infected DC began establishing RDP tunnels back to the VPN server and making requests to an internal DNS server for multiple endpoints relating to exploit kits, likely in an effort to strengthen the attacker’s foothold within the environment. Some of the endpoints requested relate to:

- EternalBlue vulnerability

- Petit Potam NTLM hash attack tool

- Unusual GitHub repositories

- Unusual Python repositories

The DC made outgoing NTLM requests to other internal devices, implying the successful installation of Petit Potam exploitation tools. The server then began performing NTLM reconnaissance, making over 1,000 successful logins under ‘Administrator’ to several other internal devices. Around the same time, the device was also seen making anonymous SMBv1 logins to numerous internal devices, (possibly symptomatic of the attacker probing machines for EternalBlue vulnerabilities).

Interestingly, the device also made numerous failed authentication attempts using a spoofed credential for one of the organization’s security managers. This was likely in an attempt to hide themselves using ‘Living off the Land’ (LotL) techniques. However, whilst the attacker clearly did their research on the company, they failed to acknowledge the typical naming convention used for credentials within the environment. This ultimately backfired and made the compromise more obvious and unusual.

In the morning of the following day, the initially compromised VPN server began conducting further reconnaissance, engaging in similar activity to that observed by the domain controller. Until now, the customer had set Darktrace RESPOND to run in human confirmation mode, meaning interventions were not made autonomously but required confirmation by a member of the internal security team. However, thanks to Proactive Threat Notifications (PTNs) delivered by Darktrace’s dedicated SOC team, the customer was made immediately aware of this unusual behaviour, allowing them to apply manual Darktrace RESPOND blocks to all outgoing connections (Figure 2). This gave the security team enough time to respond and remediate before serious damage could be done.

Figure 2: Darktrace RESPOND model breach showing the manually applied “Quarantine Device” action taken against the compromised VPN server. This screenshot displays the UI from Darktrace version 5.1

Confluence in the wild – 2. N-day attack

Towards the end of 2021, Darktrace saw a European broadcasting customer leave an Atlassian Confluence internet-facing server unpatched and vulnerable to crypto-mining malware using CVE-2021-26084. Thanks to Darktrace, this attack was entirely immobilized within only a few hours of the initial infection, protecting the organization from damage (Figure 3).

Figure 3: Timeline of the Confluence attack

On midday on September 1^st 2021, an unpatched Confluence server was seen receiving SSL connections over port 443 from a suspicious new endpoint, 178.238.226[.]127. The connections were encrypted, meaning Darktrace was unable to view the contents and ascertain what requests were being made. However, with the disclosure of CVE-2021-26084 just 7 days prior to this activity, it is likely that the TTPs used involved injecting OGNL expressions to Confluence server memory; allowing the attacker to remotely execute code on the vulnerable server.

Immediately after successful exploitation of the Confluence server, the infected device was observed making outgoing HTTP GET requests to several external endpoints using a new user agent (curl/7.61.1). Curl was used to silently download and configure multiple suspicious files relating to XMRig cryptocurrency miner, including ld.sh, XMRig and config.json. Subsequent outgoing connections were then made to europe.randomx-hub.miningpoolhub[.]com · 172.105.210[.]117 using the JSON-RPC protocol, seen alongside the mining credential maillocal.confluence (Figure 4). Only 3 seconds after initial compromise, the infected device began attempting to mine cryptocurrency using the Minergate protocol but was instantly and autonomously blocked by Darktrace RESPOND. This prevented the server from abusing system resources and generating profits for the attacker.

Figure 4: A graph showing the frequency of external connections using the JSON-RPC protocol made by the breach device over a 48-hour window. The orange-red dots represent models that breached as a result of this activity, demonstrating the “waterfall” effect commonly seen when a device suffers a compromise. This screenshot displays the UI from Darktrace version 5.1

In the afternoon, the malware persisted with its infection. The compromised server began making successive HTTP GET requests to a new rare endpoint 195.19.192[.]28 using the same curl user agent (Figures 5 & 6). These requests were for executable and dynamic library files associated with Kinsing malware (but fortunately were also blocked by Darktrace RESPOND). Kinsing is a malware strain found in numerous attack campaigns which is often associated with crypto-jacking, and has appeared in previous Darktrace blogs [9].

Figure 5: Cyber AI Analyst summarising the unusual download of Kinsing software using the new curl user agent. This screenshot displays the UI from Darktrace version 5.1

The attacker then began making HTTP POST requests to an IP 185.154.53[.]140, using the same curl user agent; likely a method for the attacker to maintain persistence within the network and establish a foothold using its C2 infrastructure. The Confluence server was then again seen attempting to mine cryptocurrency using the Minergate protocol. It made outgoing JSON-RPC connections to a different new endpoint, 45.129.2[.]107, using the following mining credential: ‘42J8CF9sQoP9pMbvtcLgTxdA2KN4ZMUVWJk6HJDWzixDLmU2Ar47PUNS5XHv4Kmfdh8aA9fbZmKHwfmFo8Wup8YtS5Kdqh2’. This was once again blocked by Darktrace RESPOND (Figure 7).

Figure 6: VirusTotal showing the unusualness of one of these external IPs [10]

Figure 7: Log data showing the action taken by Darktrace RESPOND in response to the device breaching the “Crypto Currency Mining Activity” model. This screenshot displays the UI from Darktrace version 5.1

The final activity seen from this device involved the download of additional shell scripts over HTTP associated with Kinsing, namely spre.sh and unk.sh, from 194.38.20[.]199 and 195.3.146[.]118 respectively (Figure 8). A new user agent (Wget/1.19.5 (linux-gnu)) was used when connecting to the latter endpoint, which also began concurrently initiating repeated connections indicative of C2 beaconing. These scripts help to spread the Kinsing malware laterally within the environment and may have been the attacker's last ditch efforts at furthering their compromise before Darktrace RESPOND blocked all connections from the infected Confluence server [11]. With Darktrace RESPOND's successful actions, the customer’s security team were then able to perform their own response and remediation.

Figure 8: Cyber AI Analyst revealing the last ditch efforts made by the threat actor to download further malicious software. This screenshot displays the UI from Darktrace version 5.1

Darktrace Coverage: N- vs Zero-days

In the SonicWall case the attacker was unable to achieve their actions on objectives (thanks to Darktrace's intervention). However, this incident displayed tactics of a more stealthy and sophisticated attacker - they had an exploited machine but waited for the right moment to execute their malicious code and initiate a full compromise. Due to the lack of visibility over attacker motive, it is difficult to deduce what type of actor led to this intrusion. However, with the disclosure of a zero-day vulnerability (CVE-2021-20016) not long before this attack, along with a seemingly dormant initially compromised device, it is highly possible that it was carried out by a sophisticated cyber criminal or gang.

On the other hand, the Confluence case engaged in a slightly more noisy approach; it dropped crypto mining malware on vulnerable devices in the hope that the target’s security team did not maintain visibility over their network or would merely turn a blind eye. The files downloaded and credentials observed alongside the mining activity heavily imply the use of Kinsing malware [11]. Since this vulnerability (CVE-2021-26084) emerged as an n-day attack with likely easily accessible POCs, as well as there being a lack of LotL techniques and the motive being long term monetary gain, it is possible this attack was conducted by a less sophisticated or amateur actor (script-kiddie); one that opportunistically exploits known vulnerabilities in internet-facing devices in order to make a quick profit [12].

Whilst Darktrace RESPOND was enabled in human confirmation mode only during the start of the SonicWall attack, Darktrace’s Cyber AI Analyst still offered invaluable insight into the unusual activity associated with the infected machines during both the Confluence and SonicWall compromises. SOC analysts were able to see these uncharacteristic behaviours and escalate the incident through Darktrace’s PTN and ATE services. Analysts then worked through these tickets with the customers, providing support and guidance and, in the SonicWall case, quickly helping to configure Darktrace RESPOND. In both scenarios, Darktrace RESPOND was able to block abnormal connections and enforce a device’s pattern of life, affording the security team enough time to isolate the infected machines and prevent further threats such as ransomware detonation or data exfiltration.

Concluding thoughts and dangers of third-party integrations

Organizations with internet-facing devices will inevitably suffer opportunistic zero-day and n-day attacks. While little can be done to remove the risk of zero-days entirely, ensuring that organizations keep their systems up to date will at the very least help prevent opportunistic and script-kiddies from exploiting n-day vulnerabilities.

However, it is often not always possible for organizations to keep their systems up to date, especially for those who require continuous availability. This may also pose issues for organizations that rely on, and put their trust in, third party integrations such as those explored in this blog (Confluence and SonicWall), as enforcing secure software is almost entirely out of their hands. Moreover, with the rising prevalence of remote working, it is essential now more than ever that organizations ensure their VPN devices are shielded from external threats, guidance on which has been released by the NSA/CISA [13].

These two case studies have shown that whilst organizations can configure their networks and firewalls to help identify known indicators of compromise (IoC), this ‘rearview mirror’ approach will not account for, or protect against, any new and undisclosed IoCs. With the aid of Self-Learning AI and anomaly detection, Darktrace can detect the slightest deviation from a device’s normal pattern of life and respond autonomously without the need for rules and signatures. This allows for the disruption and prevention of known and novel attacks before irreparable damage is caused- reassuring security teams that their digital estates are secure.

Thanks to Paul Jennings for his contributions to this blog.

Appendices: SonicWall (Zero-day)

Darktrace model detections

· AIA / Suspicious Chain of Administrative Credentials

· Anomalous Connection / Active Remote Desktop Tunnel

· Anomalous Connection / SMB Enumeration

· Anomalous Connection / Unusual Internal Remote Desktop

· Compliance / High Priority Compliance Model Breach

· Compliance / Outgoing NTLM Request from DC

· Device / Anomalous RDP Followed By Multiple Model Breaches

· Device / Anomalous SMB Followed By Multiple Model Breaches

· Device / ICMP Address Scan

· Device / Large Number of Model Breaches

· Device / Large Number of Model Breaches from Critical Network Device

· Device / Multiple Lateral Movement Model Breaches (PTN/Enhanced Monitoring model)

· Device / Network Scan

· Device / Possible SMB/NTLM Reconnaissance

· Device / RDP Scan

· Device / Reverse DNS Sweep

· Device / SMB Session Bruteforce

· Device / Suspicious Network Scan Activity (PTN/Enhanced Monitoring model)

· Unusual Activity / Possible RPC Recon Activity

Darktrace RESPOND (Antigena) actions (as displayed in example)

· Antigena / Network / Manual / Quarantine Device

MITRE ATT&CK Techniques Observed

IoCs

‍

Appendices: Confluence (N-day)

Darktrace model detections

· Anomalous Connection / New User Agent to IP Without Hostname

· Anomalous Connection / Posting HTTP to IP Without Hostname

· Anomalous File / EXE from Rare External Location

· Anomalous File / Script from Rare Location

· Compliance / Crypto Currency Mining Activity

· Compromise / High Priority Crypto Currency Mining (PTN/Enhanced Monitoring model)

· Device / Initial Breach Chain Compromise (PTN/Enhanced Monitoring model)

· Device / Internet Facing Device with High Priority Alert

· Device / New User Agent

Darktrace RESPOND (Antigena) actions (displayed in example)

· Antigena / Network / Compliance / Antigena Crypto Currency Mining Block

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

· Antigena / Network / External Threat / Antigena Suspicious Activity Block

· Antigena / Network / External Threat / Antigena Suspicious File Block

· Antigena / Network / Significant Anomaly / Antigena Block Enhanced Monitoring

MITRE ATT&CK Techniques Observed

IOCs

References:

[1] https://securitybrief.asia/story/why-preventing-zero-day-attacks-is-crucial-for-businesses

[2] https://electricenergyonline.com/energy/magazine/1150/article/Security-Sessions-More-Dangerous-Than-Zero-Days-The-N-Day-Threat.htm

[3] https://www.wired.com/2014/11/countdown-to-zero-day-stuxnet/

[4] https://cve.mitre.org/cgi-bin/cvekey.cgi?keyword=SonicWall+2021

[5] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-20016

[6] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2021-26084

[7] https://www.zdnet.com/article/us-cybercom-says-mass-exploitation-of-atlassian-confluence-vulnerability-ongoing-and-expected-to-accelerate/

[8] https://cve.mitre.org/cgi-bin/cvename.cgi?name=CVE-2022-26134

[9] https://attack.mitre.org/software/S0599/

[10] https://www.virustotal.com/gui/ip-address/195.19.192.28/detection

[11] https://sysdig.com/blog/zoom-into-kinsing-kdevtmpfsi/

[12] https://github.com/alt3kx/CVE-2021-26084_PoC

[13] https://www.nsa.gov/Press-Room/Press-Releases-Statements/Press-Release-View/Article/2791320/nsa-cisa-release-guidance-on-selecting-and-hardening-remote-access-vpns/

Written by

Lewis Morgan

Cyber Analyst

Inside the SOC

Written by

Lewis Morgan

Cyber Analyst

•

October 20, 2025

Nathaniel Jones

VP, Security & AI Strategy, Field CISO

•

October 15, 2025

The Darktrace Community

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October 20, 2025

Salty Much: Darktrace’s view on a recent Salt Typhoon intrusion

What is Salt Typhoon?‍

Salt Typhoon represents one of the most persistent and sophisticated cyber threats targeting global critical infrastructure today. Believed to be linked to state-sponsored actors from the People’s Republic of China (PRC), this advanced persistent threat (APT) group has executed a series of high-impact campaigns against telecommunications providers, energy networks, and government systems—most notably across the United States.

Active since at least 2019, the group—also tracked as Earth Estries, GhostEmperor, and UNC2286—has demonstrated advanced capabilities in exploiting edge devices, maintaining deep persistence, and exfiltrating sensitive data across more than 80 countries. While much of the public reporting has focused on U.S. targets, Salt Typhoon’s operations have extended into Europe, the Middle East, and Africa (EMEA) where it has targeted telecoms, government entities, and technology firms. Its use of custom malware and exploitation of high-impact vulnerabilities (e.g., Ivanti, Fortinet, Cisco) underscores the strategic nature of its campaigns, which blend intelligence collection with geopolitical influence [1].

Leveraging zero-day exploits, obfuscation techniques, and lateral movement strategies, Salt Typhoon has demonstrated an alarming ability to evade detection and maintain long-term access to sensitive environments. The group’s operations have exposed lawful intercept systems, compromised metadata for millions of users, and disrupted essential services, prompting coordinated responses from intelligence agencies and private-sector partners worldwide. As organizations reassess their threat models, Salt Typhoon serves as a stark reminder of the evolving nature of nation-state cyber operations and the urgent need for proactive defense strategies.

Darktrace’s coverage

In this case, Darktrace observed activity in a European telecommunications organisation consistent with Salt Typhoon’s known tactics, techniques and procedures (TTPs), including dynamic-link library (DLL) sideloading and abuse of legitimate software for stealth and execution.

Initial access

The intrusion likely began with exploitation of a Citrix NetScaler Gateway appliance in the first week of July 2025. From there, the actor pivoted to Citrix Virtual Delivery Agent (VDA) hosts in the client’s Machine Creation Services (MCS) subnet. Initial access activities in the intrusion originated from an endpoint potentially associated with the SoftEther VPN service, suggesting infrastructure obfuscation from the outset.

Tooling

Darktrace subsequently observed the threat actor delivering a backdoor assessed with high confidence to be SNAPPYBEE (also known as Deed RAT) [2][3] to multiple Citrix VDA hosts. The backdoor was delivered to these internal endpoints as a DLL alongside legitimate executable files for antivirus software such as Norton Antivirus, Bkav Antivirus, and IObit Malware Fighter. This pattern of activity indicates that the attacker relied on DLL side-loading via legitimate antivirus software to execute their payloads. Salt Typhoon and similar groups have a history of employing this technique [4][5], enabling them to execute payloads under the guise of trusted software and bypassing traditional security controls.

Command-and-Control (C2)

The backdoor delivered by the threat actor leveraged LightNode VPS endpoints for C2, communicating over both HTTP and an unidentified TCP-based protocol. This dual-channel setup is consistent with Salt Typhoon’s known use of non-standard and layered protocols to evade detection. The HTTP communications displayed by the backdoor included POST requests with an Internet Explorer User-Agent header and Target URI patterns such as “/17ABE7F017ABE7F0”. One of the C2 hosts contacted by compromised endpoints was aar.gandhibludtric[.]com (38.54.63[.]75), a domain recently linked to Salt Typhoon [6].

Detection timeline

Darktrace produced high confidence detections in response to the early stages of the intrusion, with both the initial tooling and C2 activities being strongly covered by both investigations by Darktrace Cyber AI Analyst^TM investigations and Darktrace models. Despite the sophistication of the threat actor, the intrusion activity identified and remediated before escalating beyond these early stages of the attack, with Darktrace’s timely high-confidence detections likely playing a key role in neutralizing the threat.

Cyber AI Analyst observations

Darktrace’s Cyber AI Analyst autonomously investigated the model alerts generated by Darktrace during the early stages of the intrusion. Through its investigations, Cyber AI Analyst discovered the initial tooling and C2 events and pieced them together into unified incidents representing the attacker’s progression.

Figure 1: Cyber AI Analyst weaved together separate events from the intrusion into broader incidents summarizing the attacker’s progression.

Conclusion

Based on overlaps in TTPs, staging patterns, infrastructure, and malware, Darktrace assesses with moderate confidence that the observed activity was consistent with Salt Typhoon/Earth Estries (ALA GhostEmperor/UNC2286). Salt Typhoon continues to challenge defenders with its stealth, persistence, and abuse of legitimate tools. As attackers increasingly blend into normal operations, detecting behavioral anomalies becomes essential for identifying subtle deviations and correlating disparate signals. The evolving nature of Salt Typhoon’s tradecraft, and its ability to repurpose trusted software and infrastructure, ensures it will remain difficult to detect using conventional methods alone. This intrusion highlights the importance of proactive defense, where anomaly-based detections, not just signature matching, play a critical role in surfacing early-stage activity.

Credit to Nathaniel Jones (VP, Security & AI Strategy, FCISO), Sam Lister (Specialist Security Researcher), Emma Foulger (Global Threat Research Operations Lead), Adam Potter (Senior Cyber Analyst)

Edited by Ryan Traill (Analyst Content Lead)

Appendices

Indicators of Compromise (IoCs)

IoC-Type-Description + Confidence

89.31.121[.]101 – IP Address – Possible C2 server

hxxp://89.31.121[.]101:443/WINMM.dll - URI – Likely SNAPPYBEE download

b5367820cd32640a2d5e4c3a3c1ceedbbb715be2 - SHA1 – Likely SNAPPYBEE download

hxxp://89.31.121[.]101:443/NortonLog.txt - URI - Likely DLL side-loading activity

hxxp://89.31.121[.]101:443/123.txt - URI - Possible DLL side-loading activity

hxxp://89.31.121[.]101:443/123.tar - URI - Possible DLL side-loading activity

hxxp://89.31.121[.]101:443/pdc.exe - URI - Possible DLL side-loading activity

hxxp://89.31.121[.]101:443//Dialog.dat - URI - Possible DLL side-loading activity

hxxp://89.31.121[.]101:443/fltLib.dll - URI - Possible DLL side-loading activity

hxxp://89.31.121[.]101:443/DisplayDialog.exe - URI - Possible DLL side-loading activity

hxxp://89.31.121[.]101:443/DgApi.dll - URI - Likely DLL side-loading activity

hxxp://89.31.121[.]101:443/dbindex.dat - URI - Likely DLL side-loading activity

hxxp://89.31.121[.]101:443/1.txt - URI - Possible DLL side-loading activity

hxxp://89.31.121[.]101:443/imfsbDll.dll – Likely DLL side-loading activity

hxxp://89.31.121[.]101:443/imfsbSvc.exe - URI – Likely DLL side-loading activity

aar.gandhibludtric[.]com – Hostname – Likely C2 server

38.54.63[.]75 – IP – Likely C2 server

156.244.28[.]153 – IP – Possible C2 server

hxxp://156.244.28[.]153/17ABE7F017ABE7F0 - URI – Possible C2 activity

MITRE TTPs

Technique | Description

T1190 | Exploit Public-Facing Application - Citrix NetScaler Gateway compromise

T1105 | Ingress Tool Transfer – Delivery of backdoor to internal hosts

T1665 | Hide Infrastructure – Use of SoftEther VPN for C2

T1574.001 | Hijack Execution Flow: DLL – Execution of backdoor through DLL side-loading

T1095 | Non-Application Layer Protocol – Unidentified application-layer protocol for C2 traffic

T1071.001| Web Protocols – HTTP-based C2 traffic

T1571| Non-Standard Port – Port 443 for unencrypted HTTP traffic

Darktrace Model Alerts during intrusion

Anomalous File::Internal::Script from Rare Internal Location

Anomalous File::EXE from Rare External Location

Anomalous File::Multiple EXE from Rare External Locations

Anomalous Connection::Possible Callback URL

Antigena::Network::External Threat::Antigena Suspicious File Block

Antigena::Network::Significant Anomaly::Antigena Significant Server Anomaly Block

Antigena::Network::Significant Anomaly::Antigena Controlled and Model Alert

Antigena::Network::Significant Anomaly::Antigena Alerts Over Time Block

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

References

[1] https://www.cisa.gov/news-events/cybersecurity-advisories/aa25-239a

[2] https://www.trendmicro.com/en_gb/research/24/k/earth-estries.html

[3] https://www.trendmicro.com/content/dam/trendmicro/global/en/research/24/k/earth-estries/IOC_list-EarthEstries.txt

[4] https://www.trendmicro.com/en_gb/research/24/k/breaking-down-earth-estries-persistent-ttps-in-prolonged-cyber-o.html

[5] https://lab52.io/blog/deedrat-backdoor-enhanced-by-chinese-apts-with-advanced-capabilities/

[6] https://www.silentpush.com/blog/salt-typhoon-2025/

^{The content provided in this blog is published by Darktrace for general informational purposes only and reflects our understanding of cybersecurity topics, trends, incidents, and developments at the time of publication. While we strive to ensure accuracy and relevance, the information is provided “as is” without any representations or warranties, express or implied. Darktrace makes no guarantees regarding the completeness, accuracy, reliability, or timeliness of any information presented and expressly disclaims all warranties.}

^{Nothing in this blog constitutes legal, technical, or professional advice, and readers should consult qualified professionals before acting on any information contained herein. Any references to third-party organizations, technologies, threat actors, or incidents are for informational purposes only and do not imply affiliation, endorsement, or recommendation.}

^{Darktrace, its affiliates, employees, or agents shall not be held liable for any loss, damage, or harm arising from the use of or reliance on the information in this blog.}

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About the author

Nathaniel Jones

VP, Security & AI Strategy, Field CISO

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AI

October 15, 2025

How a Major Civil Engineering Company Reduced MTTR across Network, Email and the Cloud with Darktrace

Asking more of the information security team

“What more can we be doing to secure the company?” is a great question for any cyber professional to hear from their Board of Directors. After successfully defeating a series of attacks and seeing the potential for AI tools to supercharge incoming threats, a UK-based civil engineering company’s security team had the answer: Darktrace.

“When things are coming at you at machine speed, you need machine speed to fight it off – it’s as simple as that,” said their Information Security Manager. “There were incidents where it took us a few hours to get to the bottom of what was going on. Darktrace changed that.”

Prevention was also the best cure. A peer organization in the same sector was still in business continuity measures 18 months after an attack, and the security team did not want to risk that level of business disruption.

Legacy tools were not meeting the team’s desired speed or accuracy

The company’s native SaaS email platform took between two and 14 days to alert on suspicious emails, with another email security tool flagging malicious emails after up to 24 days. After receiving an alert, responses often took a couple of days to coordinate. The team was losing precious time.

Beyond long detection and response times, the old email security platform was no longer performing: 19% of incoming spam was missed. Of even more concern: 6% of phishing emails reached users’ inboxes, and malware and ransomware email was also still getting through, with 0.3% of such email-borne payloads reaching user inboxes.

Choosing Darktrace

“When evaluating tools in 2023, only Darktrace had what I was looking for: an existing, mature, AI-based cybersecurity solution. ChatGPT had just come out and a lot of companies were saying ‘AI this’ and ‘AI that’. Then you’d take a look, and it was all rules- and cases-based, not AI at all,” their Information Security Manager.

The team knew that, with AI-enabled attacks on the horizon, a cybersecurity company that had already built, fielded, and matured an AI-powered cyber defense would give the security team the ability to fend off machine-speed attacks at the same pace as the attackers.

Darktrace accomplishes this with multi-layered AI that learns each organization’s normal business operations. With this detailed level of understanding, Darktrace’s Self-Learning AI can recognize unusual activity that may indicate a cyber-attack, and works to neutralize the threat with precise response actions. And it does this all at machine speed and with minimal disruption.

On the morning the team was due to present its findings, the session was cancelled – for a good reason. The Board didn’t feel further discussion was necessary because the case for Darktrace was so conclusive. The CEO described the Darktrace option as ‘an insurance policy we can’t do without’.

Saving time with Darktrace / EMAIL

Darktrace / EMAIL reduced the discovery, alert, and response process from days or weeks to seconds .

Darktrace / EMAIL automates what was originally a time-consuming and repetitive process. The team has recovered between eight and 10 working hours a week by automating much of this process using / EMAIL.

Today, Darktrace / EMAIL prevents phishing emails from reaching employees’ inboxes. The volume of hostile and unsolicited email fell to a third of its original level after Darktrace / EMAIL was set up.

Further savings with Darktrace / NETWORK and Darktrace / IDENTITY

Since its success with Darktrace / EMAIL, the company adopted two more products from the Darktrace ActiveAI Security Platform – Darktrace / NETWORK and Darktrace / IDENTITY.

These have further contributed to cost savings. An initial plan to build a 24/7 SOC would have required hiring and retaining six additional analysts, rather than the two that currently use Darktrace, costing an additional £220,000 per year in salary. With Darktrace, the existing analysts have the tools needed to become more effective and impactful.

An additional benefit: Darktrace adoption has lowered the company’s cyber insurance premiums. The security team can reallocate this budget to proactive projects.

Detection of novel threats provides reassurance

Darktrace’s unique approach to cybersecurity added a key benefit. The team’s previous tool took a rules-based approach – which was only good if the next attack featured the same characteristics as the ones on which the tool was trained.

“Darktrace looks for anomalous behavior, and we needed something that detected and responded based on use cases, not rules that might be out of date or too prescriptive,” their Information Security Manager. “Our existing provider could take a couple of days to update rules and signatures, and in this game, speed is of the essence. Darktrace just does everything we need - without delay.”

Where rules-based tools must wait for a threat to emerge before beginning to detect and respond to it, Darktrace identifies and protects against unknown and novel threats, speeding identification, response, and recovery, minimizing business disruption as a result.

Looking to the future

With Darktrace in place, the UK-based civil engineering company team has reallocated time and resources usually spent on detection and alerting to now tackle more sophisticated, strategic challenges. Darktrace has also equipped the team with far better and more regularly updated visibility into potential vulnerabilities.

“One thing that frustrates me a little is penetration testing; our ISO accreditation mandates a penetration test at least once a year, but the results could be out of date the next day,” their Information Security Manager. “Darktrace / Proactive Exposure Management will give me that view in real time – we can run it daily if needed - and that’s going to be a really effective workbench for my team.”

As the company looks to further develop its security posture, Darktrace remains poised to evolve alongside its partner.

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Self-Learning AI for Zero-Day and N-Day Attack Defense

Revisiting zero-day attacks

The N-day underdog

SonicWall in the wild – 1. Zero-day attack

Confluence in the wild – 2. N-day attack

Darktrace Coverage: N- vs Zero-days

Concluding thoughts and dangers of third-party integrations

Appendices: SonicWall (Zero-day)

MITRE ATT&CK Techniques Observed

IoCs

Appendices: Confluence (N-day)

MITRE ATT&CK Techniques Observed

IOCs

Salty Much: Darktrace’s view on a recent Salt Typhoon intrusion

How a Major Civil Engineering Company Reduced MTTR across Network, Email and the Cloud with Darktrace

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October 20, 2025

Salty Much: Darktrace’s view on a recent Salt Typhoon intrusion

What is Salt Typhoon?‍

Darktrace’s coverage

Initial access

Tooling

Command-and-Control (C2)

Detection timeline

Cyber AI Analyst observations

Conclusion

Appendices

Indicators of Compromise (IoCs)

MITRE TTPs

Darktrace Model Alerts during intrusion

References

Blog

AI

October 15, 2025

How a Major Civil Engineering Company Reduced MTTR across Network, Email and the Cloud with Darktrace

Asking more of the information security team

Legacy tools were not meeting the team’s desired speed or accuracy

Choosing Darktrace

Saving time with Darktrace / EMAIL

Further savings with Darktrace / NETWORK and Darktrace / IDENTITY

Detection of novel threats provides reassurance

Looking to the future