The presence of a specific configuration file associated with RUAG APT malware indicates potential adversary persistence and command-and-control communication. SOC teams should proactively hunt for this behavior in Azure Sentinel to identify and mitigate advanced persistent threats before they exfiltrate data or escalate within the network.
YARA Rule
rule RUAG_Bot_Config_File
{
meta:
description = "Detects a specific config file used by malware in RUAG APT case"
author = "Florian Roth"
reference = "https://goo.gl/N5MEj0"
score = 60
strings:
$s1 = "[CONFIG]" ascii
$s2 = "name = " ascii
$s3 = "exe = cmd.exe" ascii
condition:
$s1 at 0 and $s2 and $s3 and filesize < 160
}
This YARA rule can be deployed in the following contexts:
This rule contains 3 string patterns in its detection logic.
Scenario: Legitimate scheduled job for system maintenance
Description: A system administrator uses a scheduled task to run a maintenance script that temporarily creates a file with a name similar to the malicious config file.
Filter/Exclusion: Exclude files created by scheduled tasks with known legitimate names or paths (e.g., C:\Windows\Temp\maintenance_config.json).
Scenario: Configuration backup by IT admin
Description: An IT administrator manually backs up configuration files as part of a routine backup process, which includes a file named similarly to the malicious config file.
Filter/Exclusion: Exclude files with timestamps matching known backup windows or files located in backup directories (e.g., C:\Backup\config_backup_20250405.json).
Scenario: Use of legitimate config file by a security tool
Description: A security tool like CrowdStrike Falcon or Microsoft Defender ATP uses a configuration file with a similar name to the malicious one for policy settings.
Filter/Exclusion: Exclude files located in known security tool directories (e.g., C:\Program Files\CrowdStrike\falcon\config.json) or files with known tool-specific extensions.
Scenario: Admin task for log rotation or file cleanup
Description: An admin uses a script or tool like LogParser or PowerShell to rotate or clean up log files, which may generate a config-like file temporarily.
Filter/Exclusion: Exclude files with temporary or log-related extensions (e.g., .tmp, .log, .bak) or files created within a specific time window during log maintenance.
Scenario: Use of a config file by a legitimate application
Description: A legitimate application such as Docker or Kubernetes may use a configuration file with a similar name to the malicious