A recent macOS malware that was first discovered by researchers at Kaspersky is currently running rampant through dozens of different cracked copies of well-known software. Malware authors have long targeted the market for free, cracked apps available through torrent services. In recent years, many cryptominers, adware, browser hijackers and bundled software installers have all plied their warez in this way.
In addition to the campaign’s scope,macOS. Bkdr. The activator is unsettling because it seems to aim to massively infect macOS users, possibly in order to build a botnet or spread other malware. A variety of productivity and business-focused apps that might be appealing in offices are also included in the software titles targeted.
DescribemacOS. Bkdr. Activator?
The campaign was first identified by researchers earlier in January, and they observed how some novel techniques were used in its multi-stage delivery.
Initial delivery method is via a torrent link which serves a disk image containing two applications: An apparently ‘uncracked’ and unusable version of the targeted software title, and an ‘Activator’ app that patches the software to make it usable. Users are instructed to copy both items to the /Applications folder before launching the Activator program.
The Activator.app contains two malicious executables: a binary written in Swift named GUI located in the bundle’s MacOS folder, and a binary written in Objective-C named tool and stored in the Resources folder. The latter folder also contains a legitimate, signed installer for Python 3.9.
On launching the Activator.app, victims are asked for an administrator password. This is used to turn off Gatekeeper settings via the spctl master-disable command and to allow apps sourced fron ‘Anywhere’ to now run on the device.
Activator also checks for a Python install and, if absent, writes the Python package from its Resources folder to the /tmp directory.
At this point the tool binary takes over, installs Python if required, and begins a series of malicious actions. The malware uses embedded Python code to kill the Notification Center. This is likely a means to bypass Apple’s attempt to alert users via Notifications when new persistence items like LaunchAgents are installed.
The Activator contains code to install a LaunchAgent at the following path, where the %@ variable is replaced with a UUID string generated at runtime.
/Library/LaunchAgents/launched.%@.plist#regex:/Library/LaunchAgents/launched.[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}.plist
Prior to executing the Python script and installing the LaunchAgent, the tool binary attempts to retrieve a remote Python script. If the retrieval is successful, it then leverages the Apple defaults API to determine whether it has ran the same script before. Defaults allows programs to store preferences and other information that need to maintained when the application isn’t running. While it is a standard macOS technology, it has rarely been leveraged by malware.
The Activator.app computes a hash of the script and saves it to the user defaults under the key lastExecutedScriptHash. If no hash has been previously saved or the stored hash is different, the retrived script is executed.
The bundle identifier for the application is”-.” Threat hunters can look for indications of compromise with GUI by searching the defaults database.
defaults read "-.GUI"
Backdoor Activator-infected macOS torrents
On VirusTotal, we have discovered hundreds of distinct Mach-O binaries that are macOS-infected. Bkdr. the activator Some have extremely low detection rates, and some are currently completely undetectable by VirusTotal engines.
The malicious binaries we have found relate to more than 70 individual” crack” apps that have been hijacked for the Activator campaign, though the following list cannot be considered complete because new samples are still being found.
The host device should be checked for malware infection symptoms if any of the following applications were downloaded from a torrent site or somewhere other than their official distribution channels.
| 1.4.0 4K video downloader | MP3 Pro 5.1.0 to 4KYouTube | Blu-ray Player Aiseesoft | 15.6 Alarm Clock Pro |
| iOS Cleaner 1.0. 30 forAnyMP4 | 2.17.0 Battery Indicator | bike 1.18. 1 | Boxy SVG 4. 21. 1 |
| 10.0 chain timer | Manager 2.0 of Clipsy Clipboard | 7.4.1 ColorWell | 7.2.1 Cookie |
| 1. 7 Cover Desk | DaisyDisk 4.26 ( 4. 26 ) | DeliverExpress 2. 7. 11 | 4.1.4 Disk Xray |
| 5.45 Dropshare | 1.46.1 Easy Data Transform | 2. 9.11 Eon Timer | 12.0.10 Final Draft |
| My iPhone 2.4.9 needs to be fixed. | iOS Transfer 6.0.0 for FonePaw | 8.3.0.8766.0 Beta FontLab | 2.38 Fork |
| 4.0.6 ForkLift | IRC Client 1. 5 for getIRC | 2.5.0 Ghost Buster Pro | 8.2.2 GrandTotal |
| Hides 5.9.2 | 3.0 HitPaw Video Converter | 7.6.6 Infuse Pro | 2.8.0 Invisible |
| 1.6.4 Iris | iShowUInstantAdvanced 1. 4.19 | Cracked version of iTubeGo 7.4.0 | Keep it at 2.3.7. |
| 6.8.2 MacX DVD Ripper Pro | 7.9 MacX MediaTrans | 8.1.1 Magic Battery | 2.6.0 Magic Disk Cleaner |
| 5.1.2 of MarsEdit | 2.6.3 MetaImage | v4.18 of Millumin 4. d. | 1.23 of Mission Control Plus |
| 2.10.4 Money Pro | 3.3.5 MouseBoost Pro | 9.0.1 NetWorker Pro | 4. 4 Nisus Writer Express |
| 1.5.1 Omni Toolbox | 4.0.3 OmniFocus Pro | 2. 6.8 OmniReader Pro | 2.4.6 Pastebot |
| 4.6.0.2629 Perfectly Clear | Privatus 7.0.2 | 3. 2QuickLinks | Cracked RAW Power 3. 4.17 |
| Rhino-8 | 2. 3.0 of SimpleMind Pro | 5. 3.0 SiteSucker Pro | Soulver 3. 00.0 |
| SpamSieve 3.0.3 | 3.0 Swinsian | 4.0.8 SyncBird Pro | TechSmith Snagit 2023, version 2. 6. |
| 4.0.3 uDock | 2.2.6 Unclutter | 13.7.0 Valentina Studio Pro | 5.4.3 Web Confidential |
| WiFiSpoof 3. 9.3 | Editor Xliff2. 9.15 | 4.7.0 xScope | 1.7.36 zFuse Pro |
Additional Stages
The Activator malware functions as a Stage 1 installer and downloader. The tool binary constructs a hardcoded domain name string and, according to Kaspersky researchers, retrieves TXT records for this domain from a DNS server. We were unable to confirm this in our tests, but the previous research suggests that the malware uses a novel technique of retrieving base64-encoded messages from the snippets contained in the DNS responses. These are then decrypted in-memory and were seen to contain a Python script which reached out to a further remote server to download the next stage.
The final stage of these encrypted messages—a Python backdoor that enables the operator to run arbitrary commands on the infected device—turned out to be a content that could change at the user’s whim. You can read more about this stage here.
MacOS is detected by SentinelOne. Bkdr. Activator
We keep tracking and finding new malicious samples as the campaign goes on. The SentinelOne agent prevents execution or malicious samples when the policy is set to” Protect.” An alert is raised and the sample may be allowed to run for observational purposes if the policy is set to” Detect Only.”
Compromise Indicators
Paths in files
/tmp/python-3.9.6-macosx10.9.pkg
/Applications/Activator.app/Contents/MacOS/GUI
/Applications/Activator.app/Contents/Resources/tool
[~]/Library/LaunchAgents/launched.%@.plist#regex:/Library/LaunchAgents/launched.[0-9a-f]{8}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{4}-[0-9a-f]{12}.plist
Mach-Os for SHA1
01223c67c44b9cb893576c624ceeb6971d7c8a64
02a38a5dd5dcff4354fab26601dd766c1d24293e
03c4a36c06c12e3420bd410a9600e09ddb4b4211
07da6661657d72a4d9fc14990bb57f46514318a9
08503aca7610a83aeb55d5cf68be16b221f677bf
14f6e7759541de4c31e6cdc5efd4059363b748a9
192fd322a6c4df2bb0e3d743dfe84d30c82512bd
1acaf1e08a03137827b9ef1972198cf9b52d0e15
1b434829544a5a63101e4d0e45ddb65ec840c841
21a5895c184b047c7b9aa7aa4f6451acbc8be826
21e6691d8466ecc6fbf25481cc33338ad47caf5c
25e12022e796d77f2496c3c2090febd048015a9f
28de5c653b938626b5c2663de07ec3affb61da7a
29f8c0f7f3a70ec114ac3cef2a47f0c285138fdb
2c6c43cf0655a2ed0d155ea12cfb100f1fc1f770
2c6d7642dd442d1e50985b938a4c5d827720b8b2
2e0159157a2443fe41abc1643d75cc923cda6896
2f26dc03de6ad3e8c7853588a96c524b5093d37e
315b793de51286b03fdedfd7bca1aa8885dfabb8
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