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Cloud Customer Relationship Management (CRM) services are broadly used, house organization’s most critical customer data, and deliver those data to corporate users via the web. Netskope Threat Research Labs have identified malicious files related to credential stealers and backdoors residing in popular cloud CRM services. These files can be shared/collaborated on within an organization’s cloud CRM service thereby creating a new malware attack and propagation vector. The malicious files identified by the Netskope Threat Research Labs in cloud CRM services are detected by Netskope Threat Protection as Backdoor.Zbot.O, Backdoor.Generckd.3017777 and W97M.Downloader.UA.
Cloud CRM services as an attack vector in the cloud
The malicious files residing inside the cloud CRM services are typically viewed as internal files. Either the sales organization users or other users involved in the customer relationship process will open malicious files they believe to be associated with a sales engagement at a later date or as per the CRM workflow. This is a critical compromise, since some of the users may be operating on a device that they view as relatively hardened against malware. This makes them less likely to scrutinize the attachment. That said, other users involved in the customer relationship process may genuinely be on a vulnerable endpoint.
Attack delivery
The delivery of malware from cloud CRM services starts with the initial step of uploading malicious files into the enterprise service accounts. There are a number of ways in which malicious files make their way into these services. An enterprise user operating on an unmanaged and insecure device could upload files as attachments to objects in the service. A large number of enterprises provide their vendors and partners access to their CRM services for uploading documents such as invoices, purchase orders, etc. (and often these happen as automated workflows). The enterprise has no control over the vendor or partner device and, most importantly, over the files being uploaded from them. In many cases, vendor- or partner-uploaded files carry with them a high level of implicit trust. Along with these, the growth of interconnected cloud services provide new paths for malicious files to make their way into cloud CRM services. For example, a number of popular services integrate with cloud storage services such as Box, Dropbox, and Microsoft Office 365 OneDrive for Business, as well as collaboration services such as Slack. Once inside the cloud CRM service, malware get delivered to unsuspecting users via the implicit CRM workflows and collaboration features.
Attack depiction
The visual depiction of the cloud CRM service as an attack vector and Netskope Threat Protection are shown in Figure 1.
Figure 1: Visual depiction of the CRM service as an attack vector and protection using Netskope
Malware payloads
We observed three different data stealing malware payloads in popular cloud CRM services. We will talk briefly about these payloads in the following sections of this blog.
Pony payload
- MD5 – c29bef85ec6c0e1cc8bcb5a54d3e4146
- Netskope detection – Backdoor.Zbot.O
The first malware we analyzed was part of an archive file. These files typically have file name such as <bankname>.<something>.zip. The malware payload within the archived file was a PONY botnet that was leaked online a couple of years ago. The PONY botnet is infamous and well-known malware extensively used for credential stealing from software such as FTP clients, email clients, remote desktop clients, browser saved passwords, and more. The malicious file we observed had a PDF icon with the extension as executable, as shown in Figure 2.
Figure 2: Malicious archive file contains executable file with PDF icon
Once the payload gets executed, it makes a number of HTTP POST requests along with encrypted data to its command and control (C&C) server (typical PONY botnet behavior), as shown in Figure 3.
Figure 3: PONY botnet HTTP POST requests to its C&C server
The memory strings inside the executed payload show PONY’s C&C server lists along with links to payloads which will install other malware, as shown in Figure 4.
FIgure 4: C&C servers and other malware URLs list in the memory dumpThe links to C&C and other malicious URLs are down at the moment, but they probably download other malware like Zeus. The PONY botnet steals credentials from different software like FTP clients, email clients, etc., as seen from the strings found in the binary, as shown in Figure 5.
