Event Triggered Execution: Linux Inotify Process Manipulating

Adversaries may establish persistence and/or elevate privileges using system mechanisms that trigger execution based on specific events. Various operating systems have means to monitor and subscribe to events such as logons or other user activity such as running specific applications/binaries.

XProtect Encryption Abuse Data Obfuscation

Malware can abuse Apple's macOS XProtect string encryption algorithm to hide critical strings, including commands, browser paths, extension IDs, cryptocurrency wallet locations, and command-and-control (C2) details.

This technique leverages the same XOR-based encryption logic implemented in macOS’s XProtect antivirus engine, this encryption is used for “encrypted YARA rules stored within the XProtect Remediator binaries”.

The encryption process involves …

Clearing Kernel Message Anti-Forensic

The dmesg -C command clears the kernel message buffer, which stores diagnostic messages generated by the kernel. These messages include logs about hardware interactions, system events, kernel module loads, and errors such as segmentation faults. The attacker can run this command to make sure that no trace of kernel-related activity, including any anomalies caused by exploitation, remains in the message …

WMI Event Subscriptions Sandbox Evasion

Adversaries may leverage WMI event subscriptions to evade detection by triggering malicious actions only under specific conditions that are unlikely to occur in a sandboxed environment. For instance, a threat actor might configure an event subscription to monitor file system, network, or logon activity, ensuring that their second-stage payload is only downloaded and executed when a particular event suggests real …

SLDT, No Pill Sandbox Evasion

The No Pill technique is a method used by malware to determine whether it is running on a physical machine or a virtual machine. This technique relies on the fact that the Local Descriptor Table (LDT) is assigned to a processor, rather than to an operating system. On a physical machine, the location of the LDT will be zero, whereas …

VPCEXT Sandbox Evasion

The VPCEXT instruction (visual property container extender) is another anti–virtual machine trick used by malware to detect virtual systems. This technique is not documented. If the execution of the instruction does not generate an exception (illegal instruction), then the program is running on a virtual machine.

Onset Delay Sandbox Evasion

Malware will delay execution to avoid analysis by the sample. For example, a Ping can be perform during a time defined. Unlike extended sleep that will use the Sleep function, onset delay will use another way to delay execution.

The purpose of such evasive code is to delay the execution of malicious activity long enough so that automated analysis …

Checking Recent Office Files Sandbox Evasion

Another way to detect if the malware is running in a real user machine is to check if some recent Office files was opened.

Checking Installed Software Sandbox Evasion

By detecting the presence of certain software and tools commonly used in sandbox environments, such as Python interpreters, tracing utilities, debugging tools, and virtual machine software like VMware, it is possible to infer the existence of a sandbox.

This inference is based on the premise that such tools are often found in sandbox setups used for dynamic malware analysis …

Evading Specific Signature Antivirus/EDR Evasion

Some signatures are specifically designed to catch an exploit or a specific behaviour. By reversing the signature, it is possible to modify the malware to evade the signature. For example, by changing the size of the payload matching, or by changing the file's header.

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