Security Experts:

Connect with us

Hi, what are you looking for?

SecurityWeekSecurityWeek

Malware & Threats

‘WhiteShadow’ Downloader Employs Microsoft SQL for Malware Delivery

Microsoft Office macros that collectively act as a stage downloader are utilizing Microsoft SQL queries to fetch malicious payloads, Proofpoint’s security researchers report.

Microsoft Office macros that collectively act as a stage downloader are utilizing Microsoft SQL queries to fetch malicious payloads, Proofpoint’s security researchers report.

Referred to as WhiteShadow, the downloader was initially detected in August 2019, when it was delivering a variant of the Crimson remote access Trojan (RAT). In the meantime, it has evolved with the addition of detection evasion and with basic obfuscation features.

Microsoft Word and Excel documents are attached to malicious emails, and when the macros are activated, SQL queries are executed against attacker-controlled Microsoft SQL Server databases, where the malware is stored as ASCII-encoded long strings, the researchers explain

The macro retrieves the string and writes it to disk as a PKZip archive of a Windows executable, which is then executed to install the malicious payload. 

According to Proofpoint, there is no evidence to tie the current malware delivery activity with the initial WhiteShadow campaigns that dropped the Crimson RAT, a piece of malware historically linked to specific threat actor activity

The WhiteShadow downloader, the security researchers say, appears to be a component of a malware delivery service that includes a rented instance of Microsoft SQL Server to host the payloads. 

A SQLOLEDB connector, which is included by default in majority of Microsoft Office installations, is leveraged by the downloader to reach the remote Microsoft SQL Server, execute a query and save the results to a file in the form of a zipped executable.

WhiteShadow has been employing this method to download malware such as Agent Tesla, AZORult, Crimson, NanoCore, njRat, Orion Logger, Remcos, and Formbook

The use of MSSQL queries to retrieve next-stage payloads is not a novel technique, but it is an unusual one, nonetheless, the security researchers point out. 

When it comes to WhiteShadow, however, the most important aspect of the discovery is the fact that this appears to be a new malware delivery service that can be leveraged by a variety of threat actors in their attacks. 

“Organizations need to be cognizant of both the incoming malicious email and outbound traffic on TCP port 1433 which should be blocked or at least restricted on modern ACL configurations in firewalls today. Currently, these campaigns are relatively small, with message volumes in the hundreds and thousands, but we will continue to monitor associated trends,” Proofpoint concludes. 

Related: Attack Combines Phishing, Steganography, PowerShell to Deliver Malware

Related: AdvisorsBot Malware Downloader Discovered

Related: New Encrypted Downloader Delivers Metasploit Backdoor

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

Click to comment

Expert Insights

Related Content

Malware & Threats

Microsoft plans to improve the protection of Office users by blocking XLL add-ins from the internet.

Cybercrime

CISA, NSA, and MS-ISAC issued an alert on the malicious use of RMM software to steal money from bank accounts.

Cybercrime

Chinese threat actor DragonSpark has been using the SparkRAT open source backdoor in attacks targeting East Asian organizations.

Cybercrime

A recently disclosed vBulletin vulnerability, which had a zero-day status for roughly two days last week, was exploited in a hacker attack targeting the...

Application Security

Electric car maker Tesla is using the annual Pwn2Own hacker contest to incentivize security researchers to showcase complex exploit chains that can lead to...

Malware & Threats

Cybercrime in 2017 was a tumultuous year "full of twists and turns", with new (but old) infection methods, a major return to social engineering,...

Cyberwarfare

Russia-linked cyberespionage group APT29 has been observed using embassy-themed lures and the GraphicalNeutrino malware in recent attacks.

Malware & Threats

Norway‎-based DNV said a ransomware attack on its ship management software impacted 1,000 vessels.