In right this moment’s multi-stage assaults, neutralizing endpoint safety options is a crucial step within the course of, permitting menace actors to function undetected. Since 2022, we’ve seen a rise within the sophistication of malware designed to disable EDR methods on an contaminated system.
A few of these instruments are developed by ransomware teams. Others are bought from underground marketplaces – proof of this was discovered within the leaked chat logs of the Black Basta group. In lots of circumstances, packer-as-a-service choices corresponding to HeartCrypt are used to obfuscate the instruments.
EDRKillShifter was created by the RansomHub group and later made out of date by a brand new software, which can be detailed on this publish. As well as, we’ll have a look at the proof for software sharing and technical information switch amongst ransomware teams utilizing totally different builds of the described software.
AVKiller
We are going to focus first on one particular payload, an AV killer software, discovered among the many hundreds of payloads within the HeartCrypt packed samples. In a number of circumstances, the detection of this software occurred throughout an ongoing ransomware assault. Different defenders have seen proof of this software, notably Cylerian, as proven in Determine 1. There’s doable proof of an early model detailed in a Palo Alto Networks publish from January 2024.
Determine 1: Cylerian notes exercise attributable to the software in query
In a single explicit instance we noticed the EDR killer file uA8s.exe (SHA-1: 2bc75023f6a4c50b21eb54d1394a7b8417608728) was created by inserting malicious content material into the Clipboard Evaluate software in Past Evaluate, a reputable utility from Scooter Software program. (We alerted Scooter Software program to the abuse previous to publication of this publish, they usually confirmed to us that their installer, executables, and DLL are all code-signed.) The loader code was injected close to the entry level, and the malicious payload and extra loader parts have been inserted as sources. Upon execution, the payload decodes itself – it’s, in actual fact, a closely protected executable. The substantial safety on the executable is amongst 5 vital traits we famous about it:
- The code is closely protected.
- It seems to be for a driver with a five-letter random title.
- The driving force is signed with a compromised certificates.
- It targets a number of safety distributors.
- The checklist of targets varies amongst samples.
The reminiscence dump reveals the executable to be an AV killer, which on this particular case targets Sophos merchandise.
Determine 2: An excerpt from the reminiscence dump, displaying Sophos merchandise being focused
There are lots of totally different variations of this software. The precise checklist of focused safety merchandise varies extensively between them — generally just one or two are particularly focused, different occasions a bigger checklist:
Determine 3: An extra excerpt from the reminiscence dump, displaying different merchandise the software targets
It additionally makes an attempt to kill processes corresponding to MsMpEng.exe, SophosHealth.exe, SAVService.exe, and sophosui.exe:
Determine 4: A listing of processes focused by the software
We famous an extended checklist of safety merchandise focused by one or one other model of the killer:
- Bitdefender
- Cylance
- Fset
- F-Safe
- Fortinet
- HitManPro
- Kaspersky
- McAfee
- Microsoft
- SentinelOne
- Sophos
- Symantec
- Pattern Micro
- Webroot
The file searches for a driver file mraml.sys (the one we noticed had a hash of SHA-1: 21a9ca6028992828c9c360d752cb033603a2fd93). When it finds it, it masses the motive force and terminates the processes and companies from the goal checklist. The title of the SYS file is hardcoded into the executable. It’s apparently random and totally different in every pattern.
Determine 5: Capabilities within the software
If the sys file will not be current, the executable file doesn’t proceed and throws the error “Did not get machine”, however creates a service named mraml.exe. The service title appears to be depending on the motive force file.
The sys file that we recovered has faux file model info. It pretends to be a CrowdStrike Falcon Sensor Driver, however the file is signed by Changsha Hengxiang Info Expertise Co., Ltd. The signer is abused, as proven in Figures 6 and seven.
Determine 6: The small print of the digital signature reveals that it’s recognized to be abused (and revoked)
Determine 7: The certificates is revoked and has not been legitimate since 2016
The drivers signed by this certificates have been referred to as out on X earlier this 12 months and tagged as ransomware-related, as proven in Determine 8.
Determine 8: The @threatintel tweet figuring out the drivers as unhealthy
The most recent variant of the killer makes use of a special signature on the motive force file, this time from Fuzhou Dingxin Commerce Co., Ltd. This certificates can also be expired, as proven in Determine 9.
Determine 9: Signing info on the Fuzhou Dingxin Commerce certificates, invalid since 2012
Recordsdata utilizing the identical signature, virtually all of them from China or Hong Kong, have been all malicious and submitted to VirusTotal between December 2024 and March 2025.
Ransomware connection
The HeartCrypt-packed EDR killer instruments have been noticed for use in ransomware assaults. The truth is, a number of ransomware households have been sighted along with the killer.
Typical use case
In a typical assault situation, we noticed the tried execution of the HeartCrypt-packed dropper. It might drop a closely protected EDR killer executable, which in flip load a driver signed by a compromised signature.
The execution try is often blocked with one of many Mal/HCrypt- , Troj/HCrypt- , or Mal/Isher-Gen generic static detections. In different circumstances, our dynamic safety mitigations, corresponding to SysCall, DynamicShellcode, or HollowProcess, block the execution.
Malware title: Mal/HCrypt-A
Title: c:customers{}desktopvp4n.exe
"sha256" : "c793304fabb09bb631610f17097b2420ee0209bab87bb2e6811d24b252a1b05d", Moreover, we noticed that the EDR killer executable tried to load the coupled driver:
Malware title: Mal/Isher-Gen
Title: c:customers{}desktopzsogd.sys Shortly after the EDR killer try, we noticed the next ransomware alert:
Mitigation CryptoGuard V5 Coverage CryptoGuard Timestamp 2025-01-20T11:59:18 Path: C:FoPefI.ex Hash: e1ed281c521ad72484c7e5e74e50572b48ea945543c6bcbd480f698c2812cdfe Ransom be aware: README_0416f0.txt Appended file extension: .0416f0
The method hint:
1 C:FoPefI.exe [64500]
C:FoPefI.exe -only-local -pass b65{redacted}a64
2 C:WindowsSystem32services.exe [1004] *
3 C:WindowsSystem32wininit.exe [900] *
wininit.exe The ransomware on this case was RansomHub.
We have now noticed the identical sequence of occasions (EDR Killer -> ransomware) with the next ransomware households:
- Blacksuit
- RansomHug
- Medusa
- Qilin
- Dragonforce
- Crytox
- Lynx
- INC
…which is a formidable checklist of competing menace actor teams.
MedusaLocker
This was a very attention-grabbing case price particular point out, as a result of we expect the menace actor used a zero-day RCE in SimpleHelp to realize preliminary entry.
Right here we see a DynamicShellcode alert:
Mitigation DynamicShellcode Coverage HeapHeapHooray Timestamp 2025-01-22T09:53:42 Title: Setup/Uninstall Path: c:temp6Vwq.exe SHA-256 43cd3f8675e25816619f77b047ea5205b6491137c5b77cce058533a07bdc9f98 SHA-1 d58dade6ea03af145d29d896f56b2063e2b078a4 MD5 b59d7c331e96be96bcfa2633b5f32f2c
The method hint revealed that the malicious killer was executed from the JWrapper-Distant Entry element of SimpleHelp:
1 C:temp6Vwq.exe [13296] 2 C:WindowsSystem32cmd.exe [16536] * cmd.exe /c begin c:temp6Vwq.exe 3 C:ProgramDataJWrapper-Distant AccessJWrapper-Windows64JRE-00000000000-completebinRemote Entry.exe [7864] * "C:ProgramDataJWrapper-Distant AccessJWrapper-Windows64JRE-00000000000-completebinRemote Entry.exe" "-cp" "C:ProgramDataJWrapper-Distant AccessJWrapper-Distant Entry-00056451424-completecustomer.jar;C:ProgramDataJWrapper-Distant AccessJWrapper-Re
The method hint signifies that the preliminary an infection may very well be associated to the zero-day RCE exploits mentioned by Horizon3.al in January 2025.
The SHA256 hash within the DynamicShellcode alert proven above, 43cd3f8675e25816619f77b047ea5205b6491137c5b77cce058533a07bdc9f98, was later discovered on VT. It’s filled with HeartCrypt. The extracted payload has the hash: a44aa98dd837010265e4af1782b57989de07949f0c704a6325f75af956cc85de.
We noticed the identical AV Killer once more. It particularly targets merchandise from six firms: Eset, Symantec, Sophos, HitManPro, Webroot, and Kaspersky. This was adopted by way of a file beforehand recognized as Medusa ransomware:
2025-01-22 10:04:12 Mal/Medusa-C/Home windows/Temp/MilanoSoftware.exe "hash": "3a6d5694eec724726efa3327a50fad3efdc623c08d647b51e51cd578bddda3da",
INC
A June 2025 case was of particular curiosity, as a result of the EDR killer was seen utilizing a further layer of packing. This extra layer seems to be like an up to date model of the packer we described in our Impersonators paper finally 12 months’s Virus Bulletin convention. On this case, the menace actor used two totally different packers as a service providing for layered safety.
CryptoGuard flagged the ransomware:
Mitigation CryptoGuard V5 Coverage CryptoGuard Timestamp 2025-06-04T04:13:52 Ransom be aware: README.txt
It was recognized as INC ransomware:
Malware title: Troj/Inc-Gen Beacon time: 2025-06-04T04:32:33.000Z Title: c:programdata1.exe "sha256" : "e5e418da909f73050b0b38676f93ca8f0551981894e2120fb50e8f03f4e2df4f",
Earlier than that time, we noticed execution makes an attempt by the EDR killer:
Mitigation HollowProcess Coverage HollowProcessGuard Timestamp 2025-06-03T21:11:12 Title: AVG Dump Course of 25.5.10141.0 Path: C:ProgramDataCSd2.exe Hash: ce1ba2a584c7940e499194972e1bd6f829ffbae2ecf2148cdb03ceeca906d151 bd6f829ffbae2ecf2148cdb03ceeca906d151
Right here, the killer masses the motive force:
"path" : "c:programdatanoedt.sys", "sha256" : "6fc26e8ac9c44a8e461a18b20929f345f8cfc86e9a454eae3509084cf6ece3be",
The file (ce1ba2a584c7940e499194972e1bd6f829ffbae2ecf2148cdb03ceeca906d151) had the payload saved as a useful resource, with XOR encryption.
The extracted payload was a file with SHA256 worth 61557a55ad40b8c40f363c4760033ef3f4178bf92ce0db657003e718dffd25bd that had embedded executables, one in every of them being 597d4011deb4f08540e10d1419b5cbdfb38506ed53a5c0ccfb12f96c74f4a7a1, which turned out to be a HeartCrypt-packed EDR killer utilized in earlier INC ransomware incidents.
It masses the motive force noedt.sys (SHA256: 6fc26e8ac9c44a8e461a18b20929f345f8cfc86e9a454eae3509084cf6ece3be), which was additionally seen in an earlier INC incident.
Maybe probably the most regarding facet of this investigation is the proof suggesting software sharing and technical information switch between competing ransomware teams (Ransomhub, Qilin, DragonForce, and INC, to call just some). Despite the fact that these teams are opponents and have totally different enterprise and affiliate fashions, there seems to be info/software leakage between them.
To be clear, it’s not {that a} single binary of the EDR killer leaked out and was shared between menace actors. As a substitute, every assault used a special construct of the proprietary software. As well as, all variants have been then filled with the subscription-based HeartCrypt packer-as-a-service. This will subsequently be no less than considerably coordinated. It could be that details about the supply and feasibility of utilizing HeartCrypt for this objective was communicated in channels constructed for this sort of sharing — although maybe all these ransomware teams coincidentally selected to buy the exact same off-the-shelf EDR-killer.
Details about comparable sharing/leakage was lately revealed by Eset researchers, and our personal findings as detailed right here help the identical conclusion. This means that the ransomware ecosystem is extra difficult than a set of competing and combating ransomware teams – one more headache for defenders.
IOCs associated to this text can be found in our GitHub repository.
