Researchers have discovered an Out-of-Bounds Heap Read/Write vulnerability in Samba that could allow unauthenticated remote attackers to execute arbitrary code on affected installations of the free software.
The bug, tracked as CVE-2021-44142, was initially discovered at the Pwn2Own event in Austin, and researchers with Trend Micro’s Zero Day Initiative discovered additional variants of the bug which were disclosed to Samba, a free software that enables file transfer and print services between clients across operating systems using Windows, Linux and macOS.
According to Trend Micro, all versions of Samba prior to 4.13.17 running the default configuration of a VFS module called vfs_fruit (used for macOS interoperability) are vulnerable to an attack.
The cybersecurity firm says the specific flaw exists within the parsing of EA metadata in the Samba server daemon (smbd) when opening a file. Attackers can leverage the vulnerability to execute code in the context of root.
Attackers must already have written access to a file’s extended attributes, but that could be a guest or unauthenticated user if the affected server allows write access to those types of users.
Samba patched this and other vulnerabilities earlier this week, but IT teams should prioritize patching of this bug now that a detailed analysis of the flaw is out there. The company also released security fixes for Samba 4.13.17, 4.14.12, and 4.15.5, and administrators are advised to patch those immediately.
According to Trend Micro, network-attacked storage devices are likely affected by this vulnerability, and vendors are expected to release updates for their devices.
“The company’s vendor list shows that the potential sectors affected by this security concern include critical industries such as communications, energy, government, manufacturing, and science and technology, as well as consumer devices such as appliances and internet of things (IoT) devices,” Trend Micro says in an advisory.
That vendor list includes VMWare, Hewlett-Packard, Centrify, Veritas, American Megatrends and others.
Administrators are advised to focus on testing and deploying the patch to remediate the bug as well as being aware of vendors that will need to update their own products.
Trend Micro also says administrator should monitor shared file, printer and access sharing data transmissions due to the standard use of Samba for system interoperability via the SMB protocol.
“The Windows SMB, which is used for remote services, can be abused by attackers to propagate through the organization’s network, or used as a jump-off point to spread to other connected systems,” Trend Micro advises. “Administrators are advised to enable solutions that can monitor and scan for transmissions that require the vfs_fruit configurations.”
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