Threat Database Backdoors Backdoor.MSIL.Spy.ACJ

Backdoor.MSIL.Spy.ACJ

By CagedTech in Backdoors

Threat Scorecard

Threat Level: 60 % (Medium)
Infected Computers: 1
First Seen: November 18, 2025
Last Seen: February 22, 2026
OS(es) Affected: Windows

The detection of Backdoor.MSIL.Spy.ACJ indicates that your system has been compromised by a potentially malicious threat. This backdoor threat is designed to allow unauthorized access to your system, which can lead to a range of serious security issues. It is essential to understand the nature of this threat and take immediate action to remove it and prevent further damage.

What Is Backdoor.MSIL.Spy.ACJ?

Backdoor.MSIL.Spy.ACJ is a type of backdoor threat that is designed to provide unauthorized access to a compromised system. The term "backdoor" refers to a method of bypassing normal security mechanisms to gain access to a system. In this case, the Backdoor.MSIL.Spy.ACJ threat is likely to be used for malicious purposes, such as stealing sensitive information, installing additional malware, or providing a conduit for further attacks.

How Backdoor.MSIL.Spy.ACJ Operates

Backdoor threats like Backdoor.MSIL.Spy.ACJ typically operate by creating a covert channel of communication between the compromised system and a command and control server. This allows the attackers to send commands to the compromised system, steal data, and install additional malware. The threat may also attempt to hide its presence by using various evasion techniques, such as code obfuscation or anti-debugging methods.

The exact mechanisms used by Backdoor.MSIL.Spy.ACJ are not publicly known, but it is likely to use common backdoor tactics, such as exploiting vulnerabilities in software or using social engineering techniques to trick users into installing the malware.

Symptoms of Infection

Systems infected with Backdoor.MSIL.Spy.ACJ may exhibit a range of symptoms, including unusual network activity, slow system performance, and unexplained changes to system settings. Users may also notice that their system is behaving erratically, such as crashing or freezing frequently. In some cases, the threat may attempt to hide its presence, making it difficult to detect without the use of specialized security software.

  • Unusual network activity, such as unexpected outgoing connections
  • Slow system performance or responsiveness
  • Unexplained changes to system settings or files
  • Erratic system behavior, such as crashing or freezing

How to Remove Backdoor.MSIL.Spy.ACJ

  1. Boot your system in Safe Mode with Networking to prevent the malware from loading and to allow for internet access.
  2. Use a reputable anti-malware tool, such as SpyHunter, to perform a full scan of your system and remove any detected threats.
  3. Uninstall any suspicious programs or applications that may be related to the Backdoor.MSIL.Spy.ACJ threat.
  4. Reset your web browsers, including Chrome, Firefox, and Edge, to their default settings to remove any potential malware components.
  5. Reboot your system and perform another full scan with your anti-malware tool to ensure that the threat has been fully removed.

Conclusion

The detection of Backdoor.MSIL.Spy.ACJ is a serious security issue that requires immediate attention. By understanding the nature of this threat and taking prompt action to remove it, you can help prevent further damage to your system and protect your sensitive information. Remember to always use reputable security software and to follow best practices for system security to minimize the risk of infection in the future.

Analysis Report

General information

Family Name: Backdoor.MSIL.Spy.ACJ
Signature status: No Signature

Known Samples

MD5: 1e0dcdbff012aae3674094563bc713ee
SHA1: fab95fe777d7b81b0f8f2645697a9f17313515a5
SHA256: 9EE09F706A34EE6AB5AF2DD95448786FAE80B368A038E0415796CEB885EAB78B
File Size: 41.47 KB, 41472 bytes

Windows Portable Executable Attributes

  • File doesn't have "Rich" header
  • File doesn't have exports table
  • File doesn't have relocations information
  • File doesn't have security information
  • File is .NET application
  • File is 64-bit executable
  • File is console application (IMAGE_SUBSYSTEM_WINDOWS_CUI)
  • File is either console or GUI application
  • File is not packed
  • IMAGE_FILE_DLL is not set inside PE header (Executable)
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  • IMAGE_FILE_EXECUTABLE_IMAGE is set inside PE header (Executable Image)

Windows PE Version Information

Name Value
Assembly Version 1.0.0.0
File Description net_launcher
File Version 1.0.0.0
Internal Name net_launcher.exe
Legal Copyright Copyright © 2025
Original Filename net_launcher.exe
Product Name net_launcher
Product Version 1.0.0.0

File Traits

  • .NET
  • CreateThread
  • ntdll
  • RijndaelManaged
  • WriteProcessMemory
  • x64

Block Information

Total Blocks: 96
Potentially Malicious Blocks: 28
Whitelisted Blocks: 68
Unknown Blocks: 0

Visual Map

0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 x x x x x x x x x x x x x x x x x x x x x x x x x x x x
0 - Probable Safe Block
? - Unknown Block
x - Potentially Malicious Block

Windows API Usage

Category API
Syscall Use
  • ntdll.dll!NtAlertThreadByThreadId
  • ntdll.dll!NtAlpcSendWaitReceivePort
  • ntdll.dll!NtApphelpCacheControl
  • ntdll.dll!NtClearEvent
  • ntdll.dll!NtClose
  • ntdll.dll!NtCreateEvent
  • ntdll.dll!NtCreateMutant
  • ntdll.dll!NtCreatePrivateNamespace
  • ntdll.dll!NtCreateSection
  • ntdll.dll!NtCreateThreadEx
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  • ntdll.dll!NtDeviceIoControlFile
  • ntdll.dll!NtDuplicateObject
  • ntdll.dll!NtEnumerateKey
  • ntdll.dll!NtEnumerateValueKey
  • ntdll.dll!NtFreeVirtualMemory
  • ntdll.dll!NtMapViewOfSection
  • ntdll.dll!NtOpenDirectoryObject
  • ntdll.dll!NtOpenEvent
  • ntdll.dll!NtOpenFile
  • ntdll.dll!NtOpenKey
  • ntdll.dll!NtOpenKeyEx
  • ntdll.dll!NtOpenProcess
  • ntdll.dll!NtOpenProcessToken
  • ntdll.dll!NtOpenSection
  • ntdll.dll!NtOpenThreadToken
  • ntdll.dll!NtProtectVirtualMemory
  • ntdll.dll!NtQueryAttributesFile
  • ntdll.dll!NtQueryDefaultLocale
  • ntdll.dll!NtQueryDirectoryFileEx
  • ntdll.dll!NtQueryFullAttributesFile
  • ntdll.dll!NtQueryInformationFile
  • ntdll.dll!NtQueryInformationJobObject
  • ntdll.dll!NtQueryInformationProcess
  • ntdll.dll!NtQueryInformationThread
  • ntdll.dll!NtQueryInformationToken
  • ntdll.dll!NtQueryKey
  • ntdll.dll!NtQueryLicenseValue
  • ntdll.dll!NtQueryPerformanceCounter
  • ntdll.dll!NtQuerySecurityAttributesToken
  • ntdll.dll!NtQuerySecurityObject
  • ntdll.dll!NtQuerySystemInformation
  • ntdll.dll!NtQuerySystemInformationEx
  • ntdll.dll!NtQueryValueKey
  • ntdll.dll!NtQueryVirtualMemory
  • ntdll.dll!NtQueryVolumeInformationFile
  • ntdll.dll!NtQueryWnfStateData
  • ntdll.dll!NtReadFile
  • ntdll.dll!NtReadRequestData
  • ntdll.dll!NtReleaseMutant
  • ntdll.dll!NtReleaseWorkerFactoryWorker
  • ntdll.dll!NtResumeThread
  • ntdll.dll!NtSetEvent
  • ntdll.dll!NtSetInformationKey
  • ntdll.dll!NtSetInformationProcess
  • ntdll.dll!NtSetInformationThread
  • ntdll.dll!NtSetInformationVirtualMemory
  • ntdll.dll!NtSetInformationWorkerFactory
  • ntdll.dll!NtSubscribeWnfStateChange
  • ntdll.dll!NtTestAlert
  • ntdll.dll!NtTraceControl
  • ntdll.dll!NtUnmapViewOfSection
  • ntdll.dll!NtUnmapViewOfSectionEx
  • ntdll.dll!NtWaitForSingleObject
  • ntdll.dll!NtWaitForWorkViaWorkerFactory
  • ntdll.dll!NtWriteFile
  • UNKNOWN
User Data Access
  • GetUserDefaultLocaleName
  • GetUserObjectInformation
Encryption Used
  • BCryptOpenAlgorithmProvider
  • CryptAcquireContext

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