Menace actors try to abuse the open-source EDRSilencer instrument as a part of efforts to tamper endpoint detection and response (EDR) options and conceal malicious exercise.
Pattern Micro stated it detected “risk actors trying to combine EDRSilencer of their assaults, repurposing it as a method of evading detection.”
EDRSilencer, impressed by the NightHawk FireBlock instrument from MDSec, is designed to dam outbound site visitors of working EDR processes utilizing the Home windows Filtering Platform (WFP).
It helps terminating numerous processes associated to EDR merchandise from Microsoft, Elastic, Trellix, Qualys, SentinelOne, Cybereason, Broadcom Carbon Black, Tanium, Palo Alto Networks, Fortinet, Cisco, ESET, HarfangLab, and Pattern Micro.
By incorporating such professional pink teaming instruments into their arsenal, the objective is to render EDR software program ineffective and make it much more difficult to establish and take away malware.
“The WFP is a robust framework constructed into Home windows for creating community filtering and safety functions,” Pattern Micro researchers stated. “It offers APIs for builders to outline customized guidelines to watch, block, or modify community site visitors primarily based on numerous standards, equivalent to IP addresses, ports, protocols, and functions.”
“WFP is utilized in firewalls, antivirus software program, and different safety options to guard programs and networks.”
EDRSilencer takes benefit of WFP by dynamically figuring out working EDR processes and creating persistent WFP filters to dam their outbound community communications on each IPv4 and IPv6, thereby stopping safety software program from sending telemetry to their administration consoles.
The assault primarily works by scanning the system to collect an inventory of working processes related to widespread EDR merchandise, adopted by working EDRSilencer with the argument “blockedr” (e.g., EDRSilencer.exe blockedr) to inhibit outbound site visitors from these processes by configuring WFP filters.
“This permits malware or different malicious actions to stay undetected, rising the potential for profitable assaults with out detection or intervention,” the researchers stated. “This highlights the continued pattern of risk actors searching for more practical instruments for his or her assaults, particularly these designed to disable antivirus and EDR options.”
The event comes as ransomware teams’ use of formidable EDR-killing instruments like AuKill (aka AvNeutralizer), EDRKillShifter, TrueSightKiller, GhostDriver, and Terminator is on the rise, with these applications weaponizing susceptible drivers to escalate privileges and terminate security-related processes.
“EDRKillShifter enhances persistence mechanisms by using methods that guarantee its steady presence throughout the system, even after preliminary compromises are found and cleaned,” Pattern Micro stated in a current evaluation.
“It dynamically disrupts safety processes in real-time and adapts its strategies as detection capabilities evolve, staying a step forward of conventional EDR instruments.”