Menace actors are trying to abuse the open-source EDRSilencer software as a part of efforts to tamper endpoint detection and response (EDR) options and conceal malicious exercise.
Pattern Micro mentioned it detected “menace actors trying to combine EDRSilencer of their assaults, repurposing it as a method of evading detection.”
EDRSilencer, impressed by the NightHawk FireBlock software from MDSec, is designed to dam outbound visitors of operating EDR processes utilizing the Home windows Filtering Platform (WFP).
It helps terminating varied 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 respectable purple teaming instruments into their arsenal, the objective is to render EDR software program ineffective and make it much more difficult to determine and take away malware.
“The WFP is a strong framework constructed into Home windows for creating community filtering and safety functions,” Pattern Micro researchers mentioned. “It offers APIs for builders to outline customized guidelines to watch, block, or modify community visitors primarily based on varied standards, resembling 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 operating 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 assemble a listing of operating processes related to widespread EDR merchandise, adopted by operating EDRSilencer with the argument “blockedr” (e.g., EDRSilencer.exe blockedr) to inhibit outbound visitors from these processes by configuring WFP filters.
“This permits malware or different malicious actions to stay undetected, growing the potential for profitable assaults with out detection or intervention,” the researchers mentioned. “This highlights the continuing development of menace actors in search of 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 strategies that guarantee its steady presence inside the system, even after preliminary compromises are found and cleaned,” Pattern Micro mentioned 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.”