In September 2018, one of our customers was targeted by a phishing attack in attempts to infiltrate malicious code on their systems. These attempts were successful and a widespread Emotet-related malware attack followed. This is the story on how we countered and contained it with the use of Configuration Manager CB 1806 and CMPivot. One of the tricky parts was that most workstations where still Windows 7 and Windows 7 embedded. Only 20% was native Windows 10 1709.

The phishing email was well disguised and was made to believe it originated from a corporate director. The content of the email suggested that invoices had not been paid and requested the addressee to open attached Excel or PDF file and follow up. This was convincing enough to some, who indeed opened the files and clicked on whatever links or “Enable content” messages held within. This triggered the seemingly random creation of executables on the local system, which in turn contacted Command & Control servers to download further payloads.

First signs of infection came on a Tuesday, through SCCM Endpoint Protection alerts: 5 infections of an Emotet-related strain, which were all quarantined. This was reported to the Security Team lead, with no further actions other than following up on more infection alerts, if any. On Wednesday, there were about 25 reported infections and we were actively investigating.

We used the (at the time) new CMPivot feature in SCCM CB 1806 to detect malware-generated executable files which served to contact C&C and download payloads. Through SCCM Endpoint Protection, we learned there was a pattern in the filenames and the locations where they were created. Some of these executables were used to create services which ran under SYSTEM context. We then triggered PowerShell scripts on the detected systems, to stop and disable those services and to move malicious files to a holding locations. This approach rendered the files harmless, while still allowing to collect and investigate them further. We also wanted to report on systems where users had non-authorized local admin rights.

 

These are the queries we used in CMPivot:

Process | where ((CommandLine like ‘%system32//%.exe’) or (CommandLine like ‘%syswow64//%.exe’))

Process | where (CommandLine == ‘”C:\\Windows\\system32\\volumebundle.exe”‘)

Process | where (CommandLine == ‘”C:\\Windows\\system32\\volumebundle.exe”‘) | where (CreationDate == ‘2018-09-14 06:41:00’)

Process | where (CreationDate like ‘2018-09-14 06:41:00’)

File(‘%public%\\*.exe’)

Administrators | where (ObjectClass == ‘User’) | where (not (Name like ‘%Admin%’))

 

If wanted we can deliver the PS script to mitigate infections.

That same day, the Network & Security team reported a lot of C&C related activity being picked up by the CheckPoint firewall. In the days following, the outgoing traffic was monitored and firewalls kept most, if not all suspicious traffic contained. Malware infections kept spreading however and the phishing attack was still going as well. Teams were informed and staff was instructed to not open any suspected emails.

First reports came is that users had received alerts from cloud services that their credentials had been compromised. For instance, Google accounts had been used to login from IP addresses throughout the world. These credentials had been stored on the users’ computers in browser password managers.

That Wednesday evening, a crisis meeting with corporate management was held and reactive measures were discussed. The only real actions we felt we could suggest, was to cut off internet access for the time being and to shut down SMB v1 services. The first would impact business-customer productivity and was denied. The latter would severely impact business productivity as most file servers and legacy applications still used SMB v1. This suggestion was also denied. For reference: there had been a WannaCry-related attack the year before, where SMB v1 was cut off by the IT teams to prevent the attack from spreading further, which was promptly overruled by business the next day, accepting the risk of the malware spreading, in fact waving away the risk as overrated. Luckily, no files or systems were encrypted then.

On Thursday, we proposed to implement Windows Defender ATP, however, another service provider implemented Sentinel One implementation. It did not go well as prerequisites were not advertised installed correctly. Windows Embedded was not mentioned as not being supported, AFTER the wide spread deployment of SentinelOne agents through SCCM application deployment. Furthermore, despite SentinelOne actively detecting and stopping many malware strains, infections were still spreading and firewall kept picking up C&C traffic.

In the meantime, the proposed WDATP PoC was setup and agents were onboarded. However, it clashed with the still present SentinelOne agents, reporting it as malware and rendering slower systems unusable due to the high usage of CPU resources. We finally found a method to uninstall SentinelOne agents.  Again, we used CMPivot to detect and intervene on systems where this issue occurred. The results were used to create a device collection to deploy the uninstall method to.

 

These are the queries we used in CMPivot:

EventLog(‘System’) | where (EventID == 7031) and (Message like ‘%Sentinel%’)

EventLog(‘System’) | summarize countif( (Message like ‘The Sentinel Agent service terminated unexpectedly.%’) ) by Device | where (countif_ > 0)

 

The cleanup of SentinelOne was mostly successful through these methods, leaving some systems to be reinstalled completely.

ATP onboarding was successful and immediately, new malware infections were reported and contained, including strains the other product had not detected.

In the end, there were no confirmed reports of data breaches other than some users personal credentials having been stolen from browser password managers.

WDATP was purchased after a positive evaluation and thanks to Microsoft’s technical and commercial approach in supporting the deployment and CMPivot was a great addition to react when we where out of control.

If you want to look at Microsoft Defender Advanced Threat Protection , please do not hesitate to contact us at info@ob-v-us.be

Best Regards ,

The workplace & security team.

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