API Hammering Sandbox Evasion

API hammering is a technique used to delay sandbox analysis and thus avoid malware capability analysis reporting. This technique consists of calling a large amount of benign APIs like "printf" in a loop.

Thermal Zone Temperature Sandbox Evasion

The temperature sensor is used to know the current temperature of a machine. In a non-virtualized environment, the function returns valid support and output like: "25.05 C: 77.09 F: 298.2K". But for a fully virtualized environment, the return is "MSAcpi_ThermalZoneTemperature not supported" because this feature is not supported on virtualized processors.

Interestingly, this method is not valid. Not all …

GetForegroundWindow Sandbox Evasion

This technique uses the GetForegroundWindow and Sleep APIs to attempt to evade sandboxes. Many sandboxes do not alter the foreground window like a user would in a normal desktop environment.

It accomplishes this by making a call to GetForegroundWindow, which returns a handle to the current window. Then the malware sample will sleep for a short time, followed by …

CLIPBRDWNDCLASS Process Manipulating

CLIPBRDWNDCLASS is a window class that is registered by the Object Linking & Embedding (OLE) library (ole32.dll) to handle clipboard data. When a window of this class is created, it is assigned a number of window properties that store the addresses of various interfaces that are used to process clipboard data. These interfaces include the ClipboardDataObjectInterface, ClipboardRootDataObjectInterface, and …

DNS API Injection Process Manipulating

DNS API injection is a technique used by malware to evade detection by intercepting and modifying DNS (Domain Name System) requests made by a host system. The technique involves injecting code into the DNS API (Application Programming Interface) of the host system, which is a set of functions and protocols that allow communication with the DNS service. By injecting code …

Debug Registers, Hardware Breakpoints Anti-Debugging

Registers DR0 through DR3 contain the linear address associated with one of the four hardware breakpoint conditions. For anti-debugging, malware will check the contents of the first four debug registers to see if the hardware breakpoint has been set.

Execution Guardrails: Environmental Keying Defense Evasion [Mitre]

Adversaries may environmentally key payloads or other features of malware to evade defenses and constraint execution to a specific target environment. Environmental keying uses cryptography to constrain execution or actions based on adversary supplied environment specific conditions that are expected to be present on the target. Environmental keying is an implementation of Execution Guardrails that utilizes cryptographic techniques for deriving …

File Melt Others

File melting is a technique that malware uses to delete itself after it has been installed on a system. This is often done in order to avoid detection by antivirus programs or other security measures. The process of file melting involves overwriting the file with random data, making it impossible to recover the original file or to detect the presence …

Detecting Online Sandbox Sandbox Evasion

Online sandbox has become very popular for malware analysis. Several malware authors employ such techniques to avoid detection and analysis. Some of these techniques will be summarized here.

Any.Run uses a fake root certificate to spy on sandbox traffic. The first information about the system can be obtained by querying the information of the root certificate. In …

Killing Windows Event Log Anti-Forensic

Killing the Windows Event Log is a technique used by malware to prevent security professionals from detecting and analyzing it. Svchost.exe is a process that manages services on Windows operating systems.

By grouping multiple services into a single process, Svchost.exe conserves computing resources and reduces resource consumption. However, this also means that Svchost.exe manages the Event Log service, which …

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