Data protection products from both Dell EMC and VMware are impacted by three potentially serious vulnerabilities discovered by researchers at Digital Defense.
EMC told customers that its Avamar Server, NetWorker Virtual Edition and Integrated Data Protection Appliance products have a common component, the Avamar Installation Manager (AVI). This component is affected by vulnerabilities that can be combined to take complete control of a system.
The most serious of the flaws, CVE-2017-15548, allows a remote attacker to bypass authentication and gain root access to the system. The vulnerability is related to the fact that authentication is performed via a POST request that includes the username, password and a parameter named wsUrl.
“The wsURL parameter can be an arbitrary URL that the Avamar server will send an authentication SOAP request to, that includes the user provided username and password,” Digital Defense explained. “If the Avamar server receives a successful SOAP response, it will return a valid session ID. The attacker doesn’t require any specific knowledge about the targeted Avamar server to generate the successful SOAP response, a generic, validly formed SOAP response will work for multiple Avamar servers.”
The second vulnerability, CVE-2017-15549, allows an authenticated attacker with low privileges to upload malicious files to the server.
“The saveFileContents method of the UserInputService class takes a single string parameter and splits it on the ‘r’ character,” researchers said. “The first half of the parameter is a path, including the filename, and the second half of the string is the data that should be written to that path. The web server is running with root privileges, so arbitrary files can be written to arbitrary locations.”
The third security hole, CVE-2017-15550, has been described as a path traversal issue that allows an authenticated attacker with low privileges to access arbitrary files on the server.
“The getFileContents method of the UserInputService class doesn’t perform any validation of the user supplied filename parameter before retrieving the requested file from the Avamar server. Additionally, the web server runs as root, so any file can be retrieved using this vulnerability,” researchers said.
Combining the flaws allows a remote attacker to take complete control of a vulnerable system.
EMC Avamar Server 7.1.x, 7.2.x, 7.3.x, 7.4.x and 7.5.0, EMC NetWorker Virtual Edition (NVE) 9.0.x, 9.1.x and 9.2.x, and EMC Integrated Data Protection Appliance 2.0 are impacted. EMC has released patches for each of the affected products.
Digital Defense told SecurityWeek that there are more than 100 Avamar server instances accessible from the Internet – according to the Shodan search engine – which experts say is unexpected considering that the affected products are backup and deduplication appliances.
While a blog post from Digital Defense and some media reports describe the flaws as “zero-days,” the vendor has released patches prior to disclosure and there is no evidence of exploitation in the wild.
The vulnerabilities also affect VMware’s vSphere Data Protection (VDP) product. VMware informed customers of the issues on January 2, but it did not reference Digital Defense or EMC. Digital Defense told SecurityWeek that VMware’s VDP is a derivative of the EMC product and EMC informed VMware of the security bugs.