easy-accordion-free domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home/mother99/jacksonholdingcompany.com/wp-includes/functions.php on line 6114zoho-flow domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home/mother99/jacksonholdingcompany.com/wp-includes/functions.php on line 6114wordpress-seo domain was triggered too early. This is usually an indicator for some code in the plugin or theme running too early. Translations should be loaded at the init action or later. Please see Debugging in WordPress for more information. (This message was added in version 6.7.0.) in /home/mother99/jacksonholdingcompany.com/wp-includes/functions.php on line 6114IntroductionZscaler’s ThreatLabz discovered a suspicious PDF file uploaded to VirusTotal from Latvia on January 30th, 2024. This PDF file is masqueraded as an invitation letter from the Ambassador of India, inviting diplomats to a wine-tasting event in February 2024. The PDF also included a link to a fake questionnaire that redirects users to a malicious ZIP archive hosted on a compromised site, initiating the infection chain. Further threat hunting led us to the discovery of another similar PDF file uploaded to VirusTotal from Latvia in July 2023.This blog provides detailed information about a previously undocumented backdoor we named \u2018WINELOADER’. We believe that a nation-state threat actor, interested in exploiting the geopolitical relations between India and diplomats in European nations, carried out this attack. The attack is characterized by its very low volume and the advanced tactics, techniques, and procedures (TTPs) employed in the malware and command and control (C2) infrastructure. While we have not yet attributed this attack to any known APT group, we have named this threat actor SPIKEDWINE based on the wine-related theme and filenames used in different stages of the attack chain, and our investigation into the case is ongoing.Key Takeaways<\/p>\n
\tLow-volume targeted attack: The samples intentionally targeted officials from countries with Indian diplomatic missions, although VirusTotal submissions indicate a specific focus on European diplomats.
\n\tNew modular backdoor: WINELOADER has a modular design, with encrypted modules downloaded from the command and control (C2) server.
\n\tEvasive tactics: The backdoor employs techniques, including re-encryption and zeroing out memory buffers, to guard sensitive data in memory and evade memory forensics solutions.
\n\tCompromised infrastructure: The threat actor utilized compromised websites at multiple stages of the attack chain.<\/p>\n
Attack Chain<\/p>\n
Figure 1 below illustrates the multi-stage attack chain at a high level.<\/p>\n
Figure 1: Multi-stage attack chain of WINELOADER.
\nTechnical Analysis<\/p>\n
In this section, we provide a detailed analysis of each component of the attack chain initiated when a victim receives and clicks on the link within the PDF.<\/p>\n
PDF analysis<\/p>\n
The PDF file is a fake invitation to a wine-tasting event purported to take place at the Indian ambassador\u2019s residence on February 2nd, 2024. The contents are well-crafted to impersonate the Ambassador of India. The invitation contains a link to a fake questionnaire, which kickstarts the infection chain.<\/p>\n
The malicious link in the PDF invitation redirects users to a compromised site, hxxps:\/\/seeceafcleaners[.]co[.]uk\/wine.php, that proceeds to download a ZIP archive containing an HTA file – wine.hta.<\/p>\n
Figure 2 below shows the contents of the PDF file.<\/p>\n
Figure 2: The PDF invitation showcasing the malicious link.<\/p>\n
A quick analysis of the PDF file’s metadata reveals that it was generated using LibreOffice version 6.4, and the time of creation was January 29th, 2024, at 10:38 AM UTC.<\/p>\n
HTA file analysis<\/p>\n
The HTA file downloaded in the previous section contains obfuscated JavaScript code, which executes the next stage of malicious activities. The obfuscation technique used in the code exhibits patterns that match those of the publicly available obfuscator obfuscator.io.<\/p>\n
Figure 3 below shows a preview of the code inside the HTA file. Decoy content is displayed to the victim to disguise malicious activity. This content is similar to what was displayed in the original PDF (Figure 2 above) and includes information about the wine-tasting event in February 2024.<\/p>\n
Figure 3: Obfuscated JavaScript code inside the HTA file.<\/p>\n
The HTA file performs the following key functions: <\/p>\n
\tDownloads a Base64 encoded text file from the URL: seeceafcleaners[.]co[.]uk\/cert.php
\n\tSaves the text file to the path: C:WindowsTaskstext.txt
\n\tUses certutil.exe to Base64 decode the text file and write the result to a ZIP archive with the path: C:WindowsTaskstext.zip. The command used is: certutil -decode C:WindowsTaskstext.txt C:Windows\\Taskstext.zip
\n\tExtracts the contents of the ZIP archive to the path: C:WindowsTasks. The command used is: tar -xf C:WindowsTaskstext.zip -C C:WindowsTasks. The ZIP archive contains two files named sqlwriter.exe and vcruntime140.dll. Here, sqlwriter.exe is the legitimate binary signed by Microsoft and vcruntime140.dll is the malicious DLL crafted by the attacker which will be side-loaded automatically when sqlwriter.exe is executed. Per our research, sqlwriter.exe has never been abused in-the-wild by any threat actor for DLL side-loading (at least to the best of our knowledge). This implies that the threat actor in this case put in extra effort to identify a signed Microsoft executable vulnerable to DLL side-loading.
\n\tExecutes sqlwriter.exe from the path: C:WindowsTasks which will kick start the infection chain.<\/p>\n
WINELOADER binary analysis<\/p>\n
When executing sqlwriter.exe, it loads a malicious DLL named vcruntime140.dll from the same directory using DLL side-loading. The exported function set_se_translator is then executed. This function decrypts the embedded WINELOADER core module within the DLL using a hardcoded 256-byte RC4 key before executing it. This is shown in the screenshot below.<\/p>\n
Figure 4: Code section that decrypts and executes the WINELOADER core module.<\/p>\n
Each module consists of configuration data (e.g., C2 polling interval), an RC4 key, and encrypted strings, followed by the module code. Part of the decrypted WINELOADER core module is shown in Figure 5 below.<\/p>\n
Figure 5: Data structure containing relevant configuration, RC4 key, encrypted strings, and the module.<\/p>\n
WINELOADER employs the following techniques to evade detection:<\/p>\n
\tSensitive data is encrypted with a hardcoded 256-byte RC4 key. The sensitive data includes:<\/p>\n
\t\tThe core module and subsequent modules downloaded from the C2 server
\n\t\tStrings (e.g. DLL filenames and API import function names)
\n\t\tData sent and received from the C2 server<\/p>\n
\tSome strings are decrypted on use and re-encrypted shortly after.
\n\tMemory buffers for storing results from API calls or decrypted strings are zeroed after use.<\/p>\n
DLL hollowing is then used to inject WINELOADER into a randomly selected DLL from the Windows system directory. The implementation is similar to the one presented by SECFORCE in their blog. WINELOADER includes additional randomization code to ensure that different DLLs are chosen for each instance of DLL hollowing (see Figure 6). <\/p>\n
Figure 6: The randomization code used when selecting a Windows system DLL for DLL hollowing.<\/p>\n
WINELOADER is not injected into the following DLLs as they contain exported functions used by the malware:<\/p>\n
\tadvapi32.dll
\n\tapi-ms-win-crt-math-l1-1-0.dll
\n\tapi-ms-win-crt-stdio-l1-1-0.dll
\n\tbcryptprimitives.dll
\n\tiphlpapi.dll
\n\tkernel32.dll
\n\tkernelbase.dll
\n\tmscoree.dll
\n\tntdll.dll
\n\tole32.dll
\n\trpcrt4.dll
\n\tshlwapi.dll
\n\tuser32.dll
\n\twininet.dll<\/p>\n
WINELOADER will inject itself into another randomly selected DLL again via DLL hollowing before it sends the first beacon request to the C2 server.<\/p>\n
The beacon request is an HTTP GET request containing a request body, which is unusual for GET requests. All requests to the C2 server use the same User-Agent, Mozilla\/5.0 (Windows NT 10.0; Win64; x64; rv:86.1) Gecko\/20100101 Firefox\/86.1, hardcoded into the sample itself.<\/p>\n
The body of the HTTP GET request is encrypted with the same 256-byte RC4 key and the fields are as follows. We have appended a question mark to fields that we are unable to conclusively verify due to the limited data collected. This information in available in the table below.<\/p>\n
\t\t\tOffset<\/p>\n
\t\t\tLength<\/p>\n
\t\t\tName<\/p>\n
\t\t\tDescription<\/p>\n
\t\t\t0x0<\/p>\n
\t\t\t2<\/p>\n
\t\t\tLength of padding bytes (n)<\/p>\n
\t\t\tThis value is randomized (min: 255, max: 65535), stored in little-endian (LE).<\/p>\n
\t\t\t0x2<\/p>\n
\t\t\tn<\/p>\n
\t\t\tPadding bytes<\/p>\n
\t\t\tPadding bytes are randomly generated with the ProcessPrng API.<\/p>\n
\t\t\t0x2 + n<\/p>\n
\t\t\t8<\/p>\n
\t\t\tCampaign ID?<\/p>\n
\t\t\t5F D5 97 93 ED 26 CB 5A in the analyzed sample.<\/p>\n
\t\t\t0xa + n<\/p>\n
\t\t\t8<\/p>\n
\t\t\tSession ID?<\/p>\n
\t\t\tRandomly generated on execution.<\/p>\n
\t\t\t0x12 + n <\/p>\n
\t\t\t8<\/p>\n
\t\t\tLocal IP address<\/p>\n
\t\t\tThe local IP address of the infected machine.<\/p>\n
\t\t\t0x20 + n<\/p>\n
\t\t\t512<\/p>\n
\t\t\tParent process name<\/p>\n
\t\t\tIn Unicode<\/p>\n
\t\t\t0x220 + n<\/p>\n
\t\t\t512<\/p>\n
\t\t\tUser name<\/p>\n
\t\t\tIn Unicode<\/p>\n
\t\t\t0x420 + n<\/p>\n
\t\t\t30<\/p>\n
\t\t\tMachine name<\/p>\n
\t\t\tIn Unicode<\/p>\n
\t\t\t0x43e + n<\/p>\n
\t\t\t4<\/p>\n
\t\t\tParent process ID<\/p>\n
\t\t\tIn little-endian<\/p>\n
\t\t\t0x442 + n<\/p>\n
\t\t\t1<\/p>\n
\t\t\tParent process token elevation type<\/p>\n
\t\t\tInformation about the privileges of the token linked to the parent process.<\/p>\n
\t\t\t0x443 + n<\/p>\n
\t\t\t8<\/p>\n
\t\t\tPolling interval for C2 requests<\/p>\n
\t\t\tC0 d4 01 00 00 00 00 00 in the analyzed sample, translates to 120,000 ms or 2 mins between requests.<\/p>\n
\t\t\t0x44b + n<\/p>\n
\t\t\t1<\/p>\n
\t\t\tRequest type?<\/p>\n
\t\t\t1 for beacon, 2 for status update<\/p>\n
\t\t\t0x44c + n<\/p>\n
\t\t\t8<\/p>\n
\t\t\tLength of message<\/p>\n
\t\t\tIn little-endian. 0 for beacon requests<\/p>\n
\t\t\t0x454 + n<\/p>\n
\t\t\t8<\/p>\n
\t\t\tUnknown?<\/p>\n
\t\t\tObserved to match the value of the request type field.<\/p>\n
\t\t\t0x45c + n<\/p>\n
\t\t\t8<\/p>\n
\t\t\tModule ID?<\/p>\n
\t\t\t00 00 00 00 00 00 00 for the core module and 6B 19 A8 D2 69 2E 85 64 for the persistence module.<\/p>\n
\t\t\t0x464 + n<\/p>\n
\t\t\tVaries<\/p>\n
\t\t\tMessage<\/p>\n
\t\t\tOnly observed for type 2 requests.<\/p>\n
Table 1: WINELOADER C2 beacon request fields<\/p>\n
An example beacon request is shown below. The value of the Content-Length header varies across requests, as the padding length is randomized with a minimum of 1,381 bytes. <\/p>\n
The same RC4 key is then used to decrypt the response from the C2 server. The fields for the decrypted response are shown in the table below.<\/p>\n
\t\t\tOffset<\/p>\n
\t\t\tLength<\/p>\n
\t\t\tName<\/p>\n
\t\t\tDescription<\/p>\n
\t\t\t0x0<\/p>\n
\t\t\t2<\/p>\n
\t\t\tLength of padding bytes (n)<\/p>\n
\t\t\tThis value is stored in little-endian (LE).<\/p>\n
\t\t\t0x2<\/p>\n
\t\t\tn<\/p>\n
\t\t\tPadding bytes<\/p>\n
\t\t\tUnused bytes<\/p>\n
\t\t\t0x2 + n<\/p>\n
\t\t\t8<\/p>\n
\t\t\tCampaign ID?<\/p>\n
\t\t\t5F D5 97 93 ED 26 CB 5A in the analyzed sample<\/p>\n
\t\t\t0xa + n<\/p>\n
\t\t\t1<\/p>\n
\t\t\tCommand<\/p>\n
\t\t\tCommand from C2<\/p>\n
\t\t\t0xb + n <\/p>\n
\t\t\tVaries<\/p>\n
\t\t\tCommand data<\/p>\n
\t\t\tBinary data for command<\/p>\n
Table 2: WINELOADER C2 response fields<\/p>\n
The core module supports three commands:<\/p>\n
\tExecute modules from the C2 either synchronously or asynchronously (via CreateThread)
\n\tInject itself into another DLL
\n\tUpdate the sleep interval between beacon requests<\/p>\n
During our research, we obtained a persistence module from the C2 server. This module copies sqlwriter.exe and vcruntime.dll into the C:WindowsTasks directory and creates a scheduled task named MS SQL Writer with the description SQL Server VSS Writer 64-bit to execute C:WindowsTaskssqlwriter.exe daily.<\/p>\n
The persistence module offers an alternative configuration to establish registry persistence at HKEY_CURRENT_USERSOFTWAREMicrosoftWindowsCurrentVersionRunMS SQL Writer.<\/p>\n
After establishing persistence for WINELOADER, the module sends an HTTP POST request to notify the C2 server about the completed task. The request body mirrors the structure of the beacon request.
\nCommand And Control Infrastructure<\/p>\n
The threat actor leveraged compromised network infrastructure at all stages of the attack chain. We identified three compromised websites used for hosting intermediate payloads or as C2 servers.<\/p>\n
Based on our in-depth analysis of the C2 communication, we believe the C2 server only responds to specific types of requests at certain times. This measure prevents automated analysis solutions from retrieving C2 responses and modular payloads.
\nConclusion<\/p>\n
The threat discussed in this blog demonstrated advanced tactics, techniques, and procedures (TTPs), displaying a keen interest in exploiting the diplomatic relations between India and Europe. The threat actor put additional effort into remaining undetected by evading memory forensics and automated URL scanning solutions.<\/p>\n
While we cannot currently attribute this activity to any known nation-state threat actor, we continue to monitor any new developments associated with this threat actor and ensure the necessary protections for our customers against these threats.
\nZscaler Coverage<\/p>\n
Figure 7: Zscaler sandbox detection report<\/p>\n
In addition to sandbox detections, Zscaler\u2019s multilayered cloud security platform detects indicators related to WINELOADER at various levels with the following threat names:<\/p>\n
\tWin64.Downloader.WineLoader<\/p>\n
Indicators Of Compromise (IOCs)<\/p>\n
\t\t\tSHA256<\/p>\n
\t\t\tDescription<\/p>\n
\t\t\t72b92683052e0c813890caf7b4f8bfd331a8b2afc324dd545d46138f677178c4<\/p>\n
\t\t\tvcruntime140.dll (WINELOADER core module loader)<\/p>\n
\t\t\tad43bbb21e2524a71bad5312a7b74af223090a8375f586d65ff239410bbd81a7 <\/p>\n
\t\t\twine.pdf (July 2023 invitation)<\/p>\n
\t\t\t3739b2eae11c8367b576869b68d502b97676fb68d18cc0045f661fbe354afcb9 <\/p>\n
\t\t\twine.pdf (Feb 2024 invitation)<\/p>\n
\t\t\t1c7593078f69f642b3442dc558cddff4347334ed7c96cd096367afd08dca67bc <\/p>\n
\t\t\twine.hta<\/p>\n
\t\t\te477f52a5f67830d81cf417434991fe088bfec21984514a5ee22c1bcffe1f2bc<\/p>\n
\t\t\tWINELOADER core module<\/p>\n
\t\t\tf61cee951b7024fca048175ca0606bfd550437f5ba2824c50d10bef8fb54ca45<\/p>\n
\t\t\tWINELOADER core module (RC4-encrypted)<\/p>\n
\t\t\tc1223aa67a72e6c4a9a61bf3733b68bfbe08add41b73ad133a7c640ba265a19e<\/p>\n
\t\t\tWINELOADER persistence module loader<\/p>\n
\t\t\tb014cdff3ac877bdd329ca0c02bdd604817e7af36ad82f912132c50355af0920<\/p>\n
\t\t\tWINELOADER persistence module<\/p>\n
\t\t\t7600d4bb4e159b38408cb4f3a4fa19a5526eec0051c8c508ef1045f75b0f6083<\/p>\n
\t\t\tWINELOADER persistence module (RC4-encrypted)<\/p>\n
\t\t\tURL<\/p>\n
\t\t\tDescription<\/p>\n
\t\t\thxxps:\/\/castechtools[.]com\/api.php<\/p>\n
\t\t\tWINELOADER C2<\/p>\n
\t\t\thxxps:\/\/seeceafcleaners[.]co[.]uk\/cert.php<\/p>\n
\t\t\tDownloads base64-encoded ZIP archive from this URL.<\/p>\n
\t\t\thxxps:\/\/seeceafcleaners[.]co[.]uk\/wine.php<\/p>\n
\t\t\tDownloads the ZIP archive containing the wine.hta file.<\/p>\n
\t\t\thxxps:\/\/passatempobasico[.]com[.]br\/wine.php<\/p>\n
\t\t\tDownloads the ZIP archive containing the wine.hta file (IOC from July 2023).<\/p>\n
MITRE ATT&CK Framework<\/p>\n
\t\t\tID<\/p>\n
\t\t\tTactic<\/p>\n
\t\t\tDescription<\/p>\n
\t\t\tT1204.002<\/p>\n
\t\t\tUser Execution: Malicious File<\/p>\n
\t\t\tThe PDF file that masquerades as an invitation contains a malicious link.<\/p>\n
\t\t\tT1656<\/p>\n
\t\t\tImpersonation<\/p>\n
\t\t\tThe contents of the PDF are crafted to impersonate the Ambassador of India.<\/p>\n
\t\t\tT1204.001<\/p>\n
\t\t\tUser Execution: Malicious Link<\/p>\n
\t\t\tThe PDF file contains a link that leads to the download of a malicious ZIP archive.<\/p>\n
\t\t\tT1574.002<\/p>\n
\t\t\tHijack Execution Flow: DLL Side-Loading<\/p>\n
\t\t\tsqlwriter.exe is used to DLL side-load vcruntime140.dll.<\/p>\n
\t\t\tT1055.001<\/p>\n
\t\t\tProcess Injection: Dynamic-link Library Injection<\/p>\n
\t\t\tDLL hollowing is used to load a randomly chosen system DLL into sqlwriter.exe process memory and inject WINELOADER in that DLL.<\/p>\n
\t\t\tT1573.001<\/p>\n
\t\t\tEncrypted Channel: Symmetric Cryptography<\/p>\n
\t\t\tRC4 stream cipher is used to encrypt the data exchanged between WINELOADER and the C2 server. <\/p>\n
\t\t\tT1041<\/p>\n
\t\t\tExfiltration Over C2 Channel<\/p>\n
\t\t\tData is encrypted and exfiltrated to the C2 server.<\/p>\n
\t\t\tT1584<\/p>\n
\t\t\tCompromise Infrastructure<\/p>\n
\t\t\tCompromised sites are used for hosting payloads and as a C2 server.<\/p>\n
\t\t\tT1053.005<\/p>\n
\t\t\tScheduled Task\/Job: Scheduled Task<\/p>\n
\t\t\tA scheduled task with the name \u201cMS SQL Writer\u201d is created to ensure sqlwriter.exe is executed to kick-start the infection chain. <\/p>\n
\t\t\tT1547.001<\/p>\n
\t\t\tBoot or Logon Autostart Execution: Registry Run Keys\/Startup Folder<\/p>\n
\t\t\tWINELOADER can be configured to execute on Windows startup by setting the registry key at HKEY_CURRENT_USERSOFTWAREMicrosoftWindowsCurrentVersionRunMS SQL Writer. <\/p>\n
\t\t\tT1140<\/p>\n
\t\t\tDeobfuscate\/Decode Files or Information<\/p>\n
\t\t\tWINELOADER strings and modules are encrypted with RC4. Sensitive data is often re-encrypted or zeroed out after use.<\/p>\n
\t\t\tT1036.001<\/p>\n
\t\t\tMasquerading: Invalid Code Signature<\/p>\n
\t\t\tvcruntime140.dll has an invalid Microsoft code signing certificate.<\/p>\n
\t\t\tT1036.004<\/p>\n
\t\t\tMasquerading: Masquerade Task or Service<\/p>\n
\t\t\tThe scheduled task created for persistence masquerades as a legitimate Microsoft scheduled task.<\/p>\n
\t\t\tT1027.007<\/p>\n
\t\t\tObfuscated Files or Information: Dynamic API Resolution<\/p>\n
\t\t\tAPI names are decrypted before they are dynamically resolved and called.<\/p>\n
\t\t\tT1027.009<\/p>\n
\t\t\tObfuscated Files or Information: Embedded Payloads<\/p>\n
\t\t\tWINELOADER modules are encrypted with RC4 within vcruntime140.dll and C2 responses.<\/p>\n
\t\t\tT1218.005<\/p>\n
\t\t\tSystem Binary Proxy Execution: Mshta<\/p>\n
\t\t\tmshta.exe executes wine.hta, which contains malicious JS downloader code.<\/p>\n
\t\t\tT1033<\/p>\n
\t\t\tSystem Owner\/User Discovery<\/p>\n
\t\t\tWINELOADER sends the current user and system name in each C2 request.<\/p>\n
\t\t\tT1071.001<\/p>\n
\t\t\tApplication Layer Protocol: Web Protocols<\/p>\n
\t\t\tWINELOADER communicates with its C2 via HTTPS. HTTP GET requests contain a request body that is atypical of such requests.<\/p>\n
\t\t\tT1001.001<\/p>\n
\t\t\tData Obfuscation: Junk Data<\/p>\n
\t\t\tWINELOADER prepends a randomized number of junk bytes to the request data before encrypting and sending it to the C2.<\/p>\n
Appendix<\/p>\n
Below is the full 256-byte RC4 key embedded inside WINELOADER that is used to encrypt and decrypt the information exchanged between the malware and the C2 server.\u00a0\u00a0<\/p>\n
\u200b[[{“value”:”<\/p>\n
In this section, we provide a detailed analysis of each component of the attack chain initiated when a victim receives and clicks on the link within the PDF.<\/p>\n
The PDF file is a fake invitation to a wine-tasting event purported to take place at the Indian ambassador\u2019s residence on February 2nd, 2024. The contents are well-crafted to impersonate the Ambassador of India. The invitation contains a link to a fake questionnaire, which kickstarts the infection chain.<\/p>\n