AMOS macOS Stealer Steals Special Files and Browser Data

A new variant of the AMOS (Atomic) Stealer malware has emerged, targeting macOS users with sophisticated techniques to steal sensitive information.

Bitdefender’s recent analysis sheds light on this alarming development, revealing the malware’s methods and implications for individual users and organizations.

A short look into the code revealed that these files are significantly similar to other samples analysed in the last months
A short look into the code revealed that these files are significantly similar to other samples analyzed in the last months

You can analyze a malware file, network, module, and registry activity with the ANY.RUN malware sandbox, and the Threat Intelligence Lookup that will let you interact with the OS directly from the browser.

Stealthy Infiltration and Data Theft

The AMOS Stealer, first documented in early 2023, has quickly become one of the most prevalent threats to macOS users.

This new variant employs a combination of Python and Apple Script code to execute its malicious activities discreetly.

By dropping a Python script on the victim’s disk, the malware is capable of gathering a wide range of sensitive data, including files associated with crypto-wallet extensions, browser data (passwords, cookies, login data, etc.), files from Desktop and Documents directories, hardware-related and system information, and even the password of the local user account.

One of the most cunning tactics this malware uses is displaying a fake dialog impersonating the operating system.

Under the guise of a system update, it prompts users for their local account password, which, if entered, is captured and utilized for further malicious activities.

Bitdefender’s further analysis of the AMOS Stealer’s code revealed significant similarities with the RustDoor backdoor, suggesting a convergence of tactics among different malware families.

Both malware types focus on collecting sensitive files from the victim’s computer, with the AMOS Stealer being a more developed version capable of additional data theft, including the extraction of Safari browser cookies.

Distribution Tactics

The AMOS Stealer spreads through disk image files that are surprisingly small, making them less likely to raise suspicion.

These files contain a FAT binary with Mach-O files for both Intel and ARM architectures, acting as a dropper for the Python script.

A common tactic to bypass Apple’s security mechanisms involves tricking users into right-clicking and opening a seemingly innocuous “Crack Installer” application in the disk image.

Crack Installer
Crack Installer

Protecting Against AMOS Stealer

Given the stealthy nature and potential damage caused by the AMOS Stealer, macOS users must stay vigilant.

Apple’s built-in protections, such as XProtect and the Malware Removal Tool (MRT), offer some defense against known malware by automatically updating and blocking malicious software. 

However, the evolving tactics of malware creators mean that users must also adopt safe browsing habits, be cautious of unsolicited software updates, and consider additional cybersecurity measures.

The discovery of the new AMOS Stealer variant highlights the ongoing malware threat to macOS users.

AMOS (Atomic) Stealer was previously associated  with a Russian threat actor, which is again confirmed by the address of the C2 server
AMOS (Atomic) Stealer was previously associated  with a Russian threat actor, which is again confirmed by the address of the C2 server

By employing sophisticated techniques to steal a wide range of sensitive information, this malware poses a significant risk to personal and organizational security. Awareness and proactive cybersecurity practices are essential in combating this and similar threats.

IOCs

IOCs Hashes for the DMG files:

  • 0caf5b5cc825e724c912ea2a32eceb59
  • f0dc72530fa06b278b7da797e5fcb3a1
  • 6c402df53630f7a41f9ceaafdca63173
  • e5c059cc26cc430d3294694635e06aef
  • b1e0274963801a8c27ef5d6b17fe4255
  • 8672d682b0a8963704761c2cc54f7acc
  • 11183a3f8a624dbf66393f449db8212e
  • e6412f07e6f2db27c79ad501fbdb6a99
  • b1b64298a01b55720eb71145978dd96b
  • 15e64a1f7c5ca5d64f4b2a8bf60d76a0
  • 4dce69d4d030bd60ee24503b8bdda39d
  • 740e5f807102b524188ffd198fe9bb3b
  • 8c71b553c29ff57cf135863f6de7125e

IOCs for the Mach-O droppers:

  • 6aab14b38bbb6b07bd9e5b29a6514b62
  • af23cd92ab15ebcc02b91664a0adc6fb
  • d9c40f35b9eaf16a2a7b4204a4e369a8
  • 6e777e9d95945386ced5c1cbb3173854
  • bc113574cfe6b8d0fb6fb13f43be261b
  • e125d2e359995c4f4b4d262244767385
  • 98fdef18dfca95dfd75630d8f1d54322
  • a66027146c009b3fdbc29400c7c74346
  • df74b93df64240e86d8d721c03d7a8a3
  • 08fc1d03db95a69cddcd173c1311e681
  • 013f3ba3a61ba52ba00b53da40da8a2b
  • 259809091a9d4144a307c6363e32d2ea

IoCs for the Python scripts

  • 6e375185480ee26c2f31c04c36a8a0e8
  • c8ac97b9df5a2dc51be6a65e6d7bce6b
  • 70b0f6ff8facca122591249f9770d7c9
  • fba8e41640a249f638de197ad615bd72

You can block malware, including Trojans, ransomware, spyware, rootkits, worms, and zero-day exploits, with Perimeter81 malware protection. All are incredibly harmful, can wreak havoc, and damage your network.

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