Update Date
10/29/2023

Class: Downloader

Programs of this type stealthily download a variety of content from network resources. They are not malicious programs, but malicious users can use them to download malicious content onto a victim computer. If a user has installed such a program on his/her computer, or if it was installed by a system administrator, then it does not pose any threat.

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Platform: Win32

Win32 is an API on Windows NT-based operating systems (Windows XP, Windows 7, etc.) that supports execution of 32-bit applications. One of the most widespread programming platforms in the world.

Family: Snojan

No family description

Examples

A85A25C61E17164397F42F62CA10DD26
CF72E67440D55BA5F0FC023354EDCE79
2AC65CD390A381F4BEEBB4B6E100D929
64117075DC97ECB25887A7BCEC22D820
FB5133A8662A91AD0FD3EB3C5546571B

Tactics and Techniques: Mitre*

TA0002
Execution

Adversaries may abuse the Windows service control manager to execute malicious commands or payloads. The Windows service control manager (services.exe) is an interface to manage and manipulate services.(Citation: Microsoft Service Control Manager) The service control manager is accessible to users via GUI components as well as system utilities such as sc.exe and Net.


PsExec can also be used to execute commands or payloads via a temporary Windows service created through the service control manager API.(Citation: Russinovich Sysinternals) Tools such as PsExec and sc.exe can accept remote servers as arguments and may be used to conduct remote execution.


Adversaries may leverage these mechanisms to execute malicious content. This can be done by either executing a new or modified service. This technique is the execution used in conjunction with Windows Service during service persistence or privilege escalation.


T1569.002
System Services: Service Execution

Adversaries may abuse the Windows service control manager to execute malicious commands or payloads. The Windows service control manager (services.exe) is an interface to manage and manipulate services.(Citation: Microsoft Service Control Manager) The service control manager is accessible to users via GUI components as well as system utilities such as sc.exe and Net.


PsExec can also be used to execute commands or payloads via a temporary Windows service created through the service control manager API.(Citation: Russinovich Sysinternals) Tools such as PsExec and sc.exe can accept remote servers as arguments and may be used to conduct remote execution.


Adversaries may leverage these mechanisms to execute malicious content. This can be done by either executing a new or modified service. This technique is the execution used in conjunction with Windows Service during service persistence or privilege escalation.


TA0004
Privilege Escalation

Adversaries may inject dynamic-link libraries (DLLs) into processes in order to evade process-based defenses as well as possibly elevate privileges. DLL injection is a method of executing arbitrary code in the address space of a separate live process.


DLL injection is commonly performed by writing the path to a DLL in the virtual address space of the target process before loading the DLL by invoking a new thread. The write can be performed with native Windows API calls such as VirtualAllocEx and WriteProcessMemory, then invoked with CreateRemoteThread (which calls the LoadLibrary API responsible for loading the DLL). (Citation: Elastic Process Injection July 2017)


Variations of this method such as reflective DLL injection (writing a self-mapping DLL into a process) and memory module (map DLL when writing into process) overcome the address relocation issue as well as the additional APIs to invoke execution (since these methods load and execute the files in memory by manually preforming the function of LoadLibrary).(Citation: Elastic HuntingNMemory June 2017)(Citation: Elastic Process Injection July 2017)


Another variation of this method, often referred to as Module Stomping/Overloading or DLL Hollowing, may be leveraged to conceal injected code within a process. This method involves loading a legitimate DLL into a remote process then manually overwriting the module’s AddressOfEntryPoint before starting a new thread in the target process.(Citation: Module Stomping for Shellcode Injection) This variation allows attackers to hide malicious injected code by potentially backing its execution with a legitimate DLL file on disk.(Citation: Hiding Malicious Code with Module Stomping)


Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via DLL injection may also evade detection from security products since the execution is masked under a legitimate process.


T1055.001
Process Injection: Dynamic-link Library Injection

Adversaries may inject dynamic-link libraries (DLLs) into processes in order to evade process-based defenses as well as possibly elevate privileges. DLL injection is a method of executing arbitrary code in the address space of a separate live process.


DLL injection is commonly performed by writing the path to a DLL in the virtual address space of the target process before loading the DLL by invoking a new thread. The write can be performed with native Windows API calls such as VirtualAllocEx and WriteProcessMemory, then invoked with CreateRemoteThread (which calls the LoadLibrary API responsible for loading the DLL). (Citation: Elastic Process Injection July 2017)


Variations of this method such as reflective DLL injection (writing a self-mapping DLL into a process) and memory module (map DLL when writing into process) overcome the address relocation issue as well as the additional APIs to invoke execution (since these methods load and execute the files in memory by manually preforming the function of LoadLibrary).(Citation: Elastic HuntingNMemory June 2017)(Citation: Elastic Process Injection July 2017)


Another variation of this method, often referred to as Module Stomping/Overloading or DLL Hollowing, may be leveraged to conceal injected code within a process. This method involves loading a legitimate DLL into a remote process then manually overwriting the module’s AddressOfEntryPoint before starting a new thread in the target process.(Citation: Module Stomping for Shellcode Injection) This variation allows attackers to hide malicious injected code by potentially backing its execution with a legitimate DLL file on disk.(Citation: Hiding Malicious Code with Module Stomping)


Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via DLL injection may also evade detection from security products since the execution is masked under a legitimate process.


T1134
Access Token Manipulation

Adversaries may modify access tokens to operate under a different user or system security context to perform actions and bypass access controls. Windows uses access tokens to determine the ownership of a running process. A user can manipulate access tokens to make a running process appear as though it is the child of a different process or belongs to someone other than the user that started the process. When this occurs, the process also takes on the security context associated with the new token.


An adversary can use built-in Windows API functions to copy access tokens from existing processes; this is known as token stealing. These token can then be applied to an existing process (i.e. Token Impersonation/Theft) or used to spawn a new process (i.e. Create Process with Token). An adversary must already be in a privileged user context (i.e. administrator) to steal a token. However, adversaries commonly use token stealing to elevate their security context from the administrator level to the SYSTEM level. An adversary can then use a token to authenticate to a remote system as the account for that token if the account has appropriate permissions on the remote system.(Citation: Pentestlab Token Manipulation)


Any standard user can use the runas command, and the Windows API functions, to create impersonation tokens; it does not require access to an administrator account. There are also other mechanisms, such as Active Directory fields, that can be used to modify access tokens.


T1134.001
Access Token Manipulation: Token Impersonation/Theft

Adversaries may duplicate then impersonate another user’s existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using `DuplicateToken` or `DuplicateTokenEx`. The token can then be used with `ImpersonateLoggedOnUser` to allow the calling thread to impersonate a logged on user’s security context, or with `SetThreadToken` to assign the impersonated token to a thread.


An adversary may perform Token Impersonation/Theft when they have a specific, existing process they want to assign the duplicated token to. For example, this may be useful for when the target user has a non-network logon session on the system.


When an adversary would instead use a duplicated token to create a new process rather than attaching to an existing process, they can additionally Create Process with Token using `CreateProcessWithTokenW` or `CreateProcessAsUserW`. Token Impersonation/Theft is also distinct from Make and Impersonate Token in that it refers to duplicating an existing token, rather than creating a new one.


TA0005
Defense Evasion

Adversaries may inject dynamic-link libraries (DLLs) into processes in order to evade process-based defenses as well as possibly elevate privileges. DLL injection is a method of executing arbitrary code in the address space of a separate live process.


DLL injection is commonly performed by writing the path to a DLL in the virtual address space of the target process before loading the DLL by invoking a new thread. The write can be performed with native Windows API calls such as VirtualAllocEx and WriteProcessMemory, then invoked with CreateRemoteThread (which calls the LoadLibrary API responsible for loading the DLL). (Citation: Elastic Process Injection July 2017)


Variations of this method such as reflective DLL injection (writing a self-mapping DLL into a process) and memory module (map DLL when writing into process) overcome the address relocation issue as well as the additional APIs to invoke execution (since these methods load and execute the files in memory by manually preforming the function of LoadLibrary).(Citation: Elastic HuntingNMemory June 2017)(Citation: Elastic Process Injection July 2017)


Another variation of this method, often referred to as Module Stomping/Overloading or DLL Hollowing, may be leveraged to conceal injected code within a process. This method involves loading a legitimate DLL into a remote process then manually overwriting the module’s AddressOfEntryPoint before starting a new thread in the target process.(Citation: Module Stomping for Shellcode Injection) This variation allows attackers to hide malicious injected code by potentially backing its execution with a legitimate DLL file on disk.(Citation: Hiding Malicious Code with Module Stomping)


Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via DLL injection may also evade detection from security products since the execution is masked under a legitimate process.


T1055.001
Process Injection: Dynamic-link Library Injection

Adversaries may inject dynamic-link libraries (DLLs) into processes in order to evade process-based defenses as well as possibly elevate privileges. DLL injection is a method of executing arbitrary code in the address space of a separate live process.


DLL injection is commonly performed by writing the path to a DLL in the virtual address space of the target process before loading the DLL by invoking a new thread. The write can be performed with native Windows API calls such as VirtualAllocEx and WriteProcessMemory, then invoked with CreateRemoteThread (which calls the LoadLibrary API responsible for loading the DLL). (Citation: Elastic Process Injection July 2017)


Variations of this method such as reflective DLL injection (writing a self-mapping DLL into a process) and memory module (map DLL when writing into process) overcome the address relocation issue as well as the additional APIs to invoke execution (since these methods load and execute the files in memory by manually preforming the function of LoadLibrary).(Citation: Elastic HuntingNMemory June 2017)(Citation: Elastic Process Injection July 2017)


Another variation of this method, often referred to as Module Stomping/Overloading or DLL Hollowing, may be leveraged to conceal injected code within a process. This method involves loading a legitimate DLL into a remote process then manually overwriting the module’s AddressOfEntryPoint before starting a new thread in the target process.(Citation: Module Stomping for Shellcode Injection) This variation allows attackers to hide malicious injected code by potentially backing its execution with a legitimate DLL file on disk.(Citation: Hiding Malicious Code with Module Stomping)


Running code in the context of another process may allow access to the process’s memory, system/network resources, and possibly elevated privileges. Execution via DLL injection may also evade detection from security products since the execution is masked under a legitimate process.


T1134
Access Token Manipulation

Adversaries may modify access tokens to operate under a different user or system security context to perform actions and bypass access controls. Windows uses access tokens to determine the ownership of a running process. A user can manipulate access tokens to make a running process appear as though it is the child of a different process or belongs to someone other than the user that started the process. When this occurs, the process also takes on the security context associated with the new token.


An adversary can use built-in Windows API functions to copy access tokens from existing processes; this is known as token stealing. These token can then be applied to an existing process (i.e. Token Impersonation/Theft) or used to spawn a new process (i.e. Create Process with Token). An adversary must already be in a privileged user context (i.e. administrator) to steal a token. However, adversaries commonly use token stealing to elevate their security context from the administrator level to the SYSTEM level. An adversary can then use a token to authenticate to a remote system as the account for that token if the account has appropriate permissions on the remote system.(Citation: Pentestlab Token Manipulation)


Any standard user can use the runas command, and the Windows API functions, to create impersonation tokens; it does not require access to an administrator account. There are also other mechanisms, such as Active Directory fields, that can be used to modify access tokens.


T1134.001
Access Token Manipulation: Token Impersonation/Theft

Adversaries may duplicate then impersonate another user’s existing token to escalate privileges and bypass access controls. For example, an adversary can duplicate an existing token using `DuplicateToken` or `DuplicateTokenEx`. The token can then be used with `ImpersonateLoggedOnUser` to allow the calling thread to impersonate a logged on user’s security context, or with `SetThreadToken` to assign the impersonated token to a thread.


An adversary may perform Token Impersonation/Theft when they have a specific, existing process they want to assign the duplicated token to. For example, this may be useful for when the target user has a non-network logon session on the system.


When an adversary would instead use a duplicated token to create a new process rather than attaching to an existing process, they can additionally Create Process with Token using `CreateProcessWithTokenW` or `CreateProcessAsUserW`. Token Impersonation/Theft is also distinct from Make and Impersonate Token in that it refers to duplicating an existing token, rather than creating a new one.


TA0011
Command and Control

Adversaries may communicate using application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.


Protocols such as HTTP/S(Citation: CrowdStrike Putter Panda) and WebSocket(Citation: Brazking-Websockets) that carry web traffic may be very common in environments. HTTP/S packets have many fields and headers in which data can be concealed. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.


T1071.001
Application Layer Protocol: Web Protocols

Adversaries may communicate using application layer protocols associated with web traffic to avoid detection/network filtering by blending in with existing traffic. Commands to the remote system, and often the results of those commands, will be embedded within the protocol traffic between the client and server.


Protocols such as HTTP/S(Citation: CrowdStrike Putter Panda) and WebSocket(Citation: Brazking-Websockets) that carry web traffic may be very common in environments. HTTP/S packets have many fields and headers in which data can be concealed. An adversary may abuse these protocols to communicate with systems under their control within a victim network while also mimicking normal, expected traffic.


* © 2024 The MITRE Corporation. This work is reproduced and distributed with the permission of The MITRE Corporation.

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