LastPass Hack caused by an unpatched Plex software on an employee's PC
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2020-5741 | Authenticated Deserialization RCE in Plex Media Server on Windows CVE-2020-5741 is a deserialization-of-untrusted-data flaw (CWE-502) in Plex Media Server on Windows: the server deserializes a serialized Python (pickle) object supplied over the network without adequate validation. A remote attacker who has already authenticated with high-privilege credentials to the server can submit a maliciously crafted serialized object, causing the server to execute arbitrary Python code upon deserialization. Successful exploitation yields code execution in the context of the Plex Media Server process on the Windows host, exposing that machine's data and credentials and, as demonstrated in the 2022 LastPass breach, potentially providing a foothold into connected environments. Windows installations running a release without the vendor's 2020 security fix are affected; Linux/NAS deployments are outside the described scope of this flaw. Exploitation is confirmed: it carries a 72.9% EPSS probability (99th percentile), has public PoC exploits (Tenable TRA-2020-32 and a PacketStorm write-up), was added to CISA's KEV catalog on 2023-03-10, and is publicly linked to the LastPass breach, where an unpatched Plex Media Server on an employee's PC was the entry point. Do: Update Plex Media Server on every Windows host to the latest release per vendor instructions (a fix shipped in 2020), prioritizing machines used by staff with privileged or remote access, and verify versions by inventory since unpatched instances remain common. Because exploitation requires authenticated high-privilege Plex credentials, review and rotate those credentials and check affected hosts for indicators of compromise such as unexpected processes or lateral movement, as demonstrated in the LastPass incident. | 7.2 | 73% | KEV PoC ×2 |
| large≈300,000+ exposed/vulnerable Plex Media Server instances, with the Windows subset affected by this flaw |
Full article352 words · extracted from securityaffairs.com · click to collapse
The LastPass data breach was caused by the failure to update Plex on the home computer of one of the company updates.
The security breach suffered by LastPass was caused by the failure to update Plex on the home computer of one of its engineers.
Recently, the password management software firm disclosed a “second attack,” a threat actor used data stolen from the August security breach and combined it with information available from a third-party data breach. Then the attackers exploited a flaw in a third-party media software package to target the firm.
LastPass revealed that the home computer of one of its DevOp engineers was hacked as part of a sophisticated cyberattack.
The attackers targeted one of the four DevOps engineers who had access to the decryption keys needed to access the cloud storage service. The hackers installed a keylogger on the DevOp engineer’s computed and captured his master password.
The investigation conducted by the company with the help of the cybersecurity firm Mandiant confirmed the attack on the DevOps engineer’s home computer.
The attackers hacked the employee’s home computer by exploiting a deserialization of untrusted data in Plex Media Server on Windows. The issue, tracked as CVE-2020-5741 (CVSS score: 7.2), can be exploited by a remote, authenticated attacker to execute arbitrary Python code.
“We have recently been made aware of a security vulnerability related to Plex Media Server. This issue allowed an attacker with access to the server administrator’s Plex account to upload a malicious file via the Camera Upload feature and have the media server execute it. This could be done by setting the server data directory to overlap with the content location for a library on which Camera Upload was enabled.” reads the advisory published by Plex. “This issue could not be exploited without first gaining access to the server’s Plex account. This issue has been assigned CVE-2020-5741 3“
The incident demonstrates the importance of patch management, the LastPass employee has never installed security updates provided by the software vendor.
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