Threat Signal Report

More than 100 Victims Infected with DevilsTongue Spyware using Microsoft 0-day Vulnerabilities

description-logo Description

FortiGuard Labs is aware of a report that a commercially sold spyware "DevilsTongue" infected more than 100 victims by leveraging a couple of then 0-day Windows vulnerabilities which led Microsoft to release patches as part of Patch Tuesday July, 2021. The list of the victims includes politicians, human rights activists, journalists, academics, embassy workers, and political dissidents around the globe. The "DevilsTongue" spyware was developed by a private company that Microsoft labeled as "Sourgum" (a.k.a Candiru) and the company is believed to have sold its products to various government agencies.

How Serious of an Issue is This?

MEDIUM. While the "DevilsTongue" spyware infected more than 100 victims around the globe, the targets appear to have been carefully selected by the Sourgum clients, thus the attack is limited. Additionally, Microsoft has released patches for the 0-day vulnerabilities exploited by Sourgum.

How Widespread is this Attack?

According to Microsoft, "approximately half of the victims were found in Palestinian Authority, with most of the remaining victims located in Israel, Iran, Lebanon, Yemen, Spain (Catalonia), United Kingdom, Turkey, Armenia, and Singapore" and the targets are "politicians, human rights activists, journalists, academics, embassy workers, and political dissidents".

What Vulnerabilities were Exploited by DevilsTongue?

CVE-2021-31979 (Windows Kernel Elevation of Privilege Vulnerability) and CVE-2021-33771 (Windows Kernel Elevation of Privilege Vulnerability)

Are Patches Available for Reported Vulnerabilities Leveraged by DevilsTongue?

Yes, Microsoft released the patches for them as part of Patch Tuesday July, 2021.

Who was the Threat Actor that Carried out the Attack?

While DevilsTongue was developed and sold by Sourgram, the actual attacks were carried out by its clients that purchased the spyware.

Are there any Reports of Nation State Activity Associated with the Attack?

Yes. According to Microsoft and Citizen Lab, various government agencies used DevilsTongue to infect the victims. However there is no evidence that Sourgum is backed by any nation state. However there is no evidence that Sourgum, the developer of DevilsTongue, is backed by any nation state.

What do We Know about Sourgum (Candiru)?

Sourgum is a private company based in Israel and is specialized in developing and operating spyware for government agencies.

According to Citizen Lab, the company was initially founded as Candiru, their registration name has changed multiple times over the years.

What's the Goal of the Attacks?

From various reports, the goal of the attacks is to exfiltrate information from the victims.

Are there other Attacks that Sourgum was Linked to?

Citizen Lab believes Sourgum is linked to CHAINSHOT exploit kit that was used to deliver spyware as well as recent attacks reported by Google that leverage Chrome vulnerabilities. Again, Sourgum only develops and sells offensive tools but is not believed to carry out actual attacks.

What are the Chrome Vulnerabilities that were Exploited in the Attack that Sourgum may be Associated with?

CVE-2021-21166 (Chrome Object Lifecycle Issue in Audio) and CVE-2021-30551 (Chrome Type Confusion in V8).

Are the Patches Available for the Chrome Vulnerabilities?

Patch for CVE-2021-21166 and CVE-2021-30551 was released in March, 2021 and June, 2021 respectively.

What is the Status of Coverage?

FortiGuard Labs has IPS coverage in place for the vulnerabilities that were leveraged by DevilsTongue and other attacks referenced in this Threat Signal that are linked to Sourgum:

  • MS.Windows.Kernel.CVE-2021-31979.Privilege.Elevation (definitions version 18.119)
  • MS.Windows.Kernel.CVE-2021-33771.Privilege.Elevation (definitions version 18.119)
  • Google.Chrome.V8.Property.Interceptor.Type.Confusion

All known network IOC's are blocked by the FortiGuard WebFiltering Client.

Are there any Indicators Available to Determine Whether my Computer is Infected with DevilsTongue?

Microsoft provided the following Indicator of Compromises in their blog post:

File locations

The hijack DLLs are in subfolders of \system32\ime\ with names starting with 'im'. However, they are blended with legitimate DLLs in those folders. To distinguish between the malicious and benign, the legitimate DLLs are signed (on Windows 10) whereas the DevilsTongue files aren't. Example paths:

  • C:\Windows\System32\IME\IMEJP\imjpueact.dll
  • C:\Windows\system32\ime\IMETC\IMTCPROT.DLL
  • C:\Windows\system32\ime\SHARED\imecpmeid.dll

The DevilsTongue configuration files, which are AES-encrypted, are in subfolders of C:\Windows\system32\config\ and have a .dat extension. The exact paths are victim-specific, although some folder names are common across victims. As the files are AES-encrypted, any files whose size mod 16 is 0 can be considered as a possible malware config file. The config files are always in new folders, not the legitimate existing folders (e.g., on Windows 10, never in \Journal, \systemprofile, \TxR etc.). Example paths:

  • C:\Windows\system32\config\spp\ServiceState\Recovery\pac.dat
  • C:\Windows\system32\config\cy-GB\Setup\SKB\InputMethod\TupTask.dat
  • C:\Windows\system32\config\config\startwus.dat

Commonly reused folder names in the config file paths:

  • spp
  • SKB
  • curv
  • networklist
  • Licenses
  • InputMethod
  • Recovery

The .ini reg file has the unique name WimBootConfigurations.ini and is in a subfolder of system32\ime\. Example paths:

  • C:\Windows\system32\ime\SHARED\WimBootConfigurations.ini
  • C:\Windows\system32\ime\IMEJP\WimBootConfigurations.ini
  • C:\Windows\system32\ime\IMETC\WimBootConfigurations.ini

The Physmem driver is dropped into system32:

  • C:\Windows\system32\physmem.sys


The two COM keys that have been observed being hijacked for persistence are listed below with their default clean values. If their default value DLL is in the \system32\ime\ folder, the DLL is likely DevilsTongue.

  • HKLM\SOFTWARE\Classes\CLSID\{CF4CC405-E2C5-4DDD-B3CE-5E7582D8C9FA}\InprocServer32 = %systemroot%\system32\wbem\wmiutils.dll (clean default value)
  • HKLM\SOFTWARE\Classes\CLSID\{7C857801-7381-11CF-884D-00AA004B2E24}\InProcServer32 = %systemroot%\system32\wbem\wbemsvc.dll (clean default value)



Traffic Light Protocol

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Not for disclosure, restricted to participants only.
Sources may use TLP:RED when information cannot be effectively acted upon by additional parties, and could lead to impacts on a party's privacy, reputation, or operations if misused. Recipients may not share TLP:RED information with any parties outside of the specific exchange, meeting, or conversation in which it was originally disclosed. In the context of a meeting, for example, TLP:RED information is limited to those present at the meeting. In most circumstances, TLP:RED should be exchanged verbally or in person.


Limited disclosure, restricted to participants’ organizations.
Sources may use TLP:AMBER when information requires support to be effectively acted upon, yet carries risks to privacy, reputation, or operations if shared outside of the organizations involved. Recipients may only share TLP:AMBER information with members of their own organization, and with clients or customers who need to know the information to protect themselves or prevent further harm. Sources are at liberty to specify additional intended limits of the sharing: these must be adhered to.


Limited disclosure, restricted to the community.
Sources may use TLP:GREEN when information is useful for the awareness of all participating organizations as well as with peers within the broader community or sector. Recipients may share TLP:GREEN information with peers and partner organizations within their sector or community, but not via publicly accessible channels. Information in this category can be circulated widely within a particular community. TLP:GREEN information may not be released outside of the community.


Disclosure is not limited.
Sources may use TLP:WHITE when information carries minimal or no foreseeable risk of misuse, in accordance with applicable rules and procedures for public release. Subject to standard copyright rules, TLP:WHITE information may be distributed without restriction.