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.
Development Micro stated it detected “risk actors making an attempt 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 site visitors of operating 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 Development Micro.
By incorporating such official purple teaming instruments into their arsenal, the purpose is to render EDR software program ineffective and make it much more difficult to determine and take away malware.
“The WFP is a robust framework constructed into Home windows for creating community filtering and safety functions,” Development Micro researchers stated. “It supplies APIs for builders to outline customized guidelines to observe, block, or modify community site visitors based mostly 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 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 basically works by scanning the system to collect 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 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 continuing development 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 packages weaponizing weak 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,” Development Micro stated in a latest 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.”
