Operation Diànxùn: Cyberespionage Campaign Targeting Telecommunication Companies

In this report the McAfee Advanced Threat Research (ATR) Strategic Intelligence team details an espionage campaign, targeting telecommunication companies, dubbed Operation Diànxùn.

In this attack, we discovered malware using similar tactics, techniques and procedures (TTPs) to those observed in earlier campaigns publicly attributed to the threat actors RedDelta and Mustang Panda. While the initial vector for the infection is not entirely clear, we believe with a medium level of confidence that victims were lured to a domain under control of the threat actor, from which they were infected with malware which the threat actor leveraged to perform additional discovery and data collection. We believe with a medium level of confidence that the attackers used a phishing website masquerading as the Huawei company career page to target people working in the telecommunications industry.

We discovered malware that masqueraded as Flash applications, often connecting to the domain “hxxp://update.careerhuawei.net” that was under control of the threat actor. The malicious domain was crafted to look like the legitimate career site for Huawei, which has the domain: hxxp://career.huawei.com. In December, we also observed a new domain name used in this campaign: hxxp://update.huaweiyuncdn.com.

Moreover, the sample masquerading as the Flash application used the malicious domain name “flach.cn” which was made to look like the official web page for China to download the Flash application, flash.cn. One of the main differences from past attacks is the lack of use of the PlugX backdoor. However, we did identify the use of a Cobalt Strike backdoor.


By using McAfee’s telemetry, possible targets based in Southeast Asia, Europe, and the US were discovered in the telecommunication sector. We also identified a strong interest in GermanVietnamese and India telecommunication companies. Combined with the use of the fake Huawei site, we believe with a high level of confidence that this campaign was targeting the telecommunication sector. We believe with a moderate level of confidence that the motivation behind this specific campaign has to do with the ban of Chinese technology in the global 5G roll-out.


Activity linked to the Chinese group RedDelta, by peers in our industry, has been spotted in the wild since early May 2020. Previous attacks have been described targeting the Vatican and religious organizations.

In September 2020, the group continued its activity using decoy documents related to Catholicism, Tibet-Ladakh relations and the United Nations General Assembly Security Council, as well as other network intrusion activities targeting the Myanmar government and two Hong Kong universities. These attacks mainly used the PlugX backdoor using DLL side loading with legitimate software, such as Word or Acrobat, to compromise targets.

While external reports have given a new name to the group which attacked the religious institutions, we believe with a moderate level of confidence, based on the similarity of TTPs, that both attacks can be attributed to one known threat actor: Mustang Panda.

Coverage and Protection

We believe the best way to protect yourself from this type of attack is to adopt a multi-layer approach including MVISION Insights, McAfee Web Gateway, MVISION UCE and MVISION EDR.

MVISION Insights can play a key role in risk mitigation by proactively collecting intelligence on the threat and your exposure.

McAfee Web Gateway and MVISION UCE provide multi-layer web vector protection with URL Reputation check, SSL decryption, and malware emulation capabilities for analyzing dangerous active Web content such as Flash and DotNet. MVISION UCE also includes the capabilities of Remote Browser Isolation, the only solution that can provide 100% protection during web browsing.

McAfee Endpoint Security running on the target endpoint protects against Operation Dianxun with an array of prevention and detection techniques. ENS Threat Prevention and ATP provides both signature and behavioral analysis capability which proactively detects the threat. ENS also leverages Global Threat Intelligence which is updated with known IoCs. For DAT based detections, the family will be reported as Trojan-Cobalt, Trojan-FSYW, Trojan-FSYX, Trojan-FSZC and CobaltStr-FDWE.

As the last phase of the attack involves creating a backdoor for remote control of the victim via a Command and Control Server and Cobalt Strike Beacon, the blocking features that can be activated on a Next Generation Intrusion Prevention System solution such as McAfee NSP are important, NSP includes a Callback Detection engine and is able to detect and block anomalies in communication signals with C2 Servers.

MVISION EDR can proactively identify persistence and defense evasion techniques. You can also use MVISION EDR to search the indicators of compromise in Real-Time or Historically (up to 90 days) across enterprise systems.

Learn more about Operation Diànxùn, including Yara & Mitre ATT&CK techniques, by reading our technical analysis and Defender blog. 

Summary of the Threat

We assess with a high level of confidence that:

  • Recent attacks using TTPs similar to those of the Chinese groups RedDelta and Mustang Panda have been discovered.
  • Multiple overlaps including tooling, network and operating methods suggest strong similarities between Chinese groups RedDelta and Mustang Panda.
  • The targets are mainly telecommunication companies based in Southeast Asia, Europe, and the US. We also identified a strong interest in German and Vietnamese telecommunication companies.

We assess with a moderate level of confidence that:

  • We believe that this espionage campaign is aimed at stealing sensitive or secret information in relation to 5G technology.

PLEASE NOTE:  We have no evidence that the technology company Huawei was knowingly involved in this Campaign.

McAfee Advanced Threat Research (ATR) is actively monitoring this threat and will update as its visibility into the threat increases.

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