Microsoft Azure Services Flaws Could’ve Exposed Cloud Resources to Unauthorized Access

Jan 17, 2023Ravie LakshmananCloud Security / Bug Report

Four different Microsoft Azure services have been found
vulnerable to server-side request forgery (SSRF^[1]) attacks that could be
exploited to gain unauthorized access to cloud resources.

The security issues, which were discovered by Orca between
October 8, 2022 and December 2, 2022 in Azure API Management, Azure
Functions, Azure Machine Learning, and Azure Digital Twins, have
since been addressed by Microsoft.

“The discovered Azure SSRF vulnerabilities allowed an attacker
to scan local ports, find new services, endpoints, and sensitive
files – providing valuable information on possibly vulnerable
servers and services to exploit for initial entry and the location
of sensitive information to target,” Orca researcher By Lidor Ben
Shitrit said^[2]
in a report shared with The Hacker News.

Two of the vulnerabilities affecting Azure Functions and Azure
Digital Twins could be abused without requiring any authentication,
enabling a threat actor to seize control of a server without even
having an Azure account in the first place.

SSRF attacks could have serious consequences^[3]
as they enable a malicious interloper to read or update internal
resources, and worse, pivot to other parts of the network, breach
otherwise unreachable systems to extract valuable data.

Three of the flaws are rated Important in severity, while the
SSRF flaw impacting Azure Machine Learning is rated Low in
severity. All the weaknesses can be leveraged to manipulate a
server to mount further attacks against a susceptible target.

A brief summary of the four vulnerabilities is as follow –

• Unauthenticated SSRF on Azure Digital Twins Explorer via a flaw
  in the /proxy/blob endpoint that could be exploited to get a
  response from any service that’s suffixed with
  “blob.core.windows[.]net”
• Unauthenticated SSRF on Azure Functions that could be exploited
  to enumerate local ports and access internal endpoints
• Authenticated SSRF on Azure API Management service that could
  be exploited to list internal ports, including one associated with
  a source code management service that could then be used to access
  sensitive files
• Authenticated SSRF on Azure Machine Learning service via the
  /datacall/streamcontent endpoint that could be exploited to fetch
  content from arbitrary endpoints

To mitigate such threats, organizations are recommended to
validate all input, ensure that servers are configured to only
allow necessary inbound and outbound traffic, avoid
misconfigurations, and adhere to the principle of least privilege
(PoLP^[4]).

“The most notable aspect of these discoveries is arguably the
number of SSRF vulnerabilities we were able to find with only
minimal effort, indicating just how prevalent they are^[5]
and the risk they pose in cloud environments,” Ben Shitrit
said.