Security Experts:

Connect with us

Hi, what are you looking for?


Cloud Security

Hard-Coded Credentials Found in Alpine Linux Docker Images

For the past three years, Alpine Linux Docker images have been shipped with a NULL password for the root user, Cisco’s Talos security researchers have discovered. 

For the past three years, Alpine Linux Docker images have been shipped with a NULL password for the root user, Cisco’s Talos security researchers have discovered. 

The hard-coded credentials were included in the Official Alpine Linux Docker images since v3.3, as part of a regression introduced in December 2015. 

Featuring a CVSS score of 9.8, this Critical vulnerability was found to impact Alpine Docker versions 3.3 to 3.9, as well as Alpine Docker Edge. 

The issue is that, in the affected builds of the Alpine Docker Image, the /etc/shadow file contains a blank field instead of the encrypted password. This means that the system treats the root user as having no password. 

“Due to the nature of this issue, systems deployed using affected versions of the Alpine Linux container that utilize Linux PAM, or some other mechanism that uses the system shadow file as an authentication database, may accept a NULL password for the root user,” Talos explains

The vulnerability was first spotted in 2015. However, about a week after it was patched, a commit was pushed to simplify the regression tests. The commit removed the ‘disable root by default’ flag from the ‘edge’ build properties file, thus reintroducing the very same flaw to subsequent builds.

With the default build options appearing to have been copied from this properties file, the flaw has been missing from all tagged builds since December 2015.

Talos reported the vulnerability to the vendor in February. Several days later, it was discovered that the issue was made public on the Alpine Linux’s Github before, although it was not flagged as a security issue and remained unresolved. 

The researchers also point out that the root account should be explicitly disabled in Docker images that are based on the affected versions. 

“The likelihood of exploitation of this vulnerability is environment-dependent, as successful exploitation requires that an exposed service or application utilise Linux PAM, or some other mechanism which uses the system shadow file as an authentication database,” Talos notes. 

Related: Container Escape Flaw Hits AWS, Google Cloud, Linux Distros

Related: Code Execution in Alpine Linux Impacts Containers

Written By

Ionut Arghire is an international correspondent for SecurityWeek.

Click to comment

Expert Insights

Related Content

Application Security

Cycode, a startup that provides solutions for protecting software source code, emerged from stealth mode on Tuesday with $4.6 million in seed funding.

Cloud Security

VMware vRealize Log Insight vulnerability allows an unauthenticated attacker to take full control of a target system.

Application Security

A CSRF vulnerability in the source control management (SCM) service Kudu could be exploited to achieve remote code execution in multiple Azure services.

Application Security

Many developers and security people admit to having experienced a breach effected through compromised API credentials.

Cloud Security

Orca Security published details on four server-side request forgery (SSRF) vulnerabilities impacting different Azure services.

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...

Cloud Security

Cloud Disaster Recovery - Ingredients for a Recipe that Saves Money and Offers a Safe, More Secure Situation with Greater Accessibility

Application Security

Software maker Adobe on Tuesday released security patches for 29 documented vulnerabilities across multiple enterprise-facing products and warned that hackers could exploit these bugs...