Enhancing Forensic Investigations After a Security Breach with Microsoft Azure Storage Logs

After a security breach, forensic investigators must act swiftly to trace the attacker’s movements. Security experts have identified that Microsoft Azure Storage logs are often a crucial yet overlooked source of evidence. These logs can provide invaluable insights for reconstructing an attack, tracing data theft, and identifying security vulnerabilities. Azure Storage Accounts, which can store vast amounts of sensitive information, are prime targets for threat actors seeking to exfiltrate data. However, the diagnostic logging that captures malicious activities is not always enabled by default, creating a significant blind spot for incident response teams. Without these logs, vital evidence regarding how attackers accessed and stole data may be irretrievably lost. Threat actors exploit various weaknesses, including misconfigured security settings, weak access controls, and leaked credentials. Common methods of attack include the misuse of Shared Access Signature (SAS) tokens and the exposure of Storage Account keys, which grant privileged access to data.

Once logging is correctly enabled, investigators can access the StorageBlobLogs table within Azure’s Log Analytics. This table captures essential details about every read, write, and delete operation on stored data. Key fields within the logs provide a digital breadcrumb trail of the attacker’s actions. The OperationName field identifies specific actions taken, such as “GetBlob” for downloading files or “PutBlob” for uploading. The CallerIpAddress reveals the requester’s IP address, helping to pinpoint the origin of malicious activity. The UserAgentHeader offers insights into the tools used for data access, distinguishing between web browsers, the Azure portal, or specialised tools like AzCopy. The AuthenticationType field indicates how the user authenticated, whether through standard credentials, a SAS token, or an Account Key. By analysing these fields, investigators can differentiate between legitimate user activity and that of a threat actor. For instance, a sudden spike in “ListContainers” or “ListBlobs” operations from an unknown IP address may suggest an attacker is mapping the storage environment. Tracking “GetBlob” operations can confirm data exfiltration and identify which files were accessed. The investigation often begins by correlating suspicious sign-ins from Microsoft Entra ID with activity in the storage logs. In one scenario, a compromised user account with administrative privileges may be used to grant another malicious account access roles like “Storage Blob Data Contributor.” 

Categories: Forensic Investigation, Azure Storage Security, Threat Detection and Prevention 

Tags: Security Breach, Forensic Investigators, Microsoft Azure, Storage Logs, Data Theft, Threat Actors, Access Controls, Shared Access Signature, Digital Breadcrumb Trail, Incident Response