Experts shed the light on mysterious critical VMware vCenter Server issue
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2020-3950 | Setuid-Based Local Privilege Escalation in VMware Fusion and Mac Clients VMware Fusion, VMware Remote Console for Mac, and Horizon Client for Mac contain a local privilege escalation flaw (CWE-269, Improper Privilege Management) caused by improper use of setuid binaries, which run with elevated privileges when executed. An attacker who already has normal (non-root) user access to a Mac where one of these products is installed can invoke the misconfigured setuid binaries to execute code as root. Successful exploitation grants full root-level control over the affected machine, with high impact on confidentiality, integrity, and availability (CVSS 3.1: 7.8). Only macOS installations of Fusion 11.x before 11.5.2, VMRC for Mac 11.x and prior before 11.0.1, and Horizon Client for Mac 5.x and prior before 5.4.0 are affected. Public proof-of-concept exploits are available, and CISA added the CVE to the Known Exploited Vulnerabilities catalog on 2021-11-03, confirming exploitation in the wild; whether ransomware operators use it is unknown. Do: Upgrade affected Macs to VMware Fusion 11.5.2 or later, VMRC for Mac 11.0.1 or later, and Horizon Client for Mac 5.4.0 or later, per VMware's instructions. Because exploitation requires local user access, prioritize multi-user Macs and machines where untrusted users can execute code; inventory managed Macs for these products and verify installed versions. As the CVE is on the CISA KEV catalog, apply the vendor updates as the required action. | 7.8 | 7% | KEV PoC ×2 |
| largehundreds of thousands of Mac endpoints with vulnerable versions of Fusion, VMRC for Mac, or Horizon Client for Mac installed (order-of-magnitude estimate) | |
| CVE-2020-3951 | VMware Workstation (15.x before 15.5.2) and Horizon Client for Windows (5.x and prior before 5.4.0) contain a denial-of-service vulnerability due to a heap-over VMware Workstation (15.x before 15.5.2) and Horizon Client for Windows (5.x and prior before 5.4.0) contain a denial-of-service vulnerability due to a heap-overflow issue in Cortado Thinprint. Attackers with non-administrative access to a guest VM with virtual printing enabled may exploit this issue to create a denial-of-service condition of the Thinprint service running on the system where Workstation or Horizon Client is installed. NVD description · AI analysis pending | 3.8 | <1% |
| — | ||
| CVE-2020-3952 | Authentication Bypass in VMware vCenter Server 6.7 vmdir (CVE-2020-3952) CVE-2020-3952 is a critical missing-authentication flaw (CWE-306, CVSS 9.8) in vmdir, the VMware Directory Service that ships with vCenter Server as part of an embedded or external Platform Services Controller (PSC). Under certain conditions, vmdir does not correctly implement access controls, so an unauthenticated attacker with network access to the directory service (LDAP) can retrieve directory data without valid credentials. Because that directory data includes vCenter Single Sign-On account information such as credential material, public proof-of-concept content treats the bug as an authentication bypass that can lead to full privileged access to vCenter. Any organization running VMware vCenter Server 6.7 with an embedded or external PSC is affected. Exploitation is confirmed: the flaw was added to CISA's KEV on 2021-11-03, and EPSS assigns a 90.4% probability of exploitation within 30 days (ransomware linkage: unknown). Do: Upgrade vCenter Server 6.7 to the patched release from VMware (the fix shipped in the 6.7 U3l update per VMware advisory VMSA-2020-0004; apply updates per vendor instructions as required by the KEV listing). Until patched, restrict untrusted network access to vmdir's LDAP service (TCP 389/636) on embedded/external PSCs and review directory logs for unauthenticated access. Inventory whether each vCenter deployment uses an embedded or external PSC, since both topologies are affected. | 9.8 | 90% | KEV PoC |
| largetens of thousands of internet-exposed vCenter Servers (~60,000+ observed in public scans at the time), with hundreds of thousands of deployments worldwide… |
Full article616 words · extracted from securityaffairs.com · click to collapse
Security firm Guardicore released technical information on a critical VMware vCenter Server vulnerability recently disclosed by VMware.
Earlier this month, VMware has addressed a critical information disclosure flaw, tracked as CVE-2020-3952, that could be exploited by attackers to compromise vCenter Server or other services that use the Directory Service (vmdir) for authentication.
The CVE-2020-3952 vulnerability has received a CVSSv3 score of 10, it resides in the vCenter Server version 6.7 on Windows and virtual appliances.
According to VMware, the vulnerability could be exploited only on vCenter Server installs that ware upgraded from a previous version. Clean installs of vCenter Server 6.7 (embedded or external PSC) are not impacted. At the time, VMware did not disclose technical details about the vulnerability.
The vulnerability has been addressed with the release of the 6.7u3f update.
“A sensitive information disclosure vulnerability in the VMware Directory Service (vmdir) was privately reported to VMware. vCenter updates are available to address this vulnerability.” reads the advisory published by WMware. “Under certain conditions1 vmdir that ships with VMware vCenter Server, as part of an embedded or external Platform Services Controller (PSC), does not correctly implement access controls. VMware has evaluated the severity of this issue to be in the Critical severity range with a maximum CVSSv3 base score of 10.0.”
Now experts at Guardicore analyzed the patch issued by VMware and released the technical analysis of the vulnerability.
An attacker with network access to a vCenter Server LDAP service can exploit the issue to create a user with full privileges on the vCenter Directory gaining full control over the VMware deployment.
“We were able to implement a proof of concept for this exploit that enacts a remote takeover of the entire vSphere deployment.” reads the post published by Guardicore.
“The vulnerability is enabled by two critical issues in vmdir’s legacy LDAP handling code:
- A bug in a function named VmDirLegacyAccessCheck which causes it to return “access granted” when permissions checks fail.
- A security design flaw which grants root privileges to an LDAP session with no token, under the assumption that it is an internal operation.”
Guardicore speculates WMware was aware of the issue, but for some reason, it failed to address it.
“Despite the relative clarity of VMware’s code, it looks like there were quite a few missteps that went into the vulnerability. The developers were at least partially aware of them, too, as we saw in the code comments and commit messages.” continues Guardicore.
“The fix to VmDirLegacyAccessCheck isn’t any more than band-aid — had VMware looked into this bug in-depth they would have found a series of issues that need to be addressed: the strange semantics of bIsAnonymousBind, the disastrous handling of pAccessToken, and, of course, the bug we started from, in VmDirLegacyAccessCheck.”
Experts highlighted that the bugfix to VmDirLegacyAccessCheck was written nearly three years ago, and the company only now released it.
“Three years is a long time for something as critical as an LDAP privilege escalation not to make it into the release schedule — especially when it turns out to be much more than a privilege escalation,” the experts conclude.
In March, VMware has released security updates to address high severity privilege escalation and denial-of-service (DoS) flaws in the Workstation, Fusion, Remote Console and Horizon Client.
The two security vulnerabilities have been tracked as CVE-2020-3950 and CVE-2020-3951 respectively.
The CVE-2020-3950 is a privilege escalation vulnerability caused by the improper use of setuid binaries, it could be exploited by attackers to escalate privileges to root.
The CVE-2020-3951 vulnerability is a denial-of-service issue caused by a heap-overflow issue in Cortado Thinprint.
| [adrotate banner=”9″] | [adrotate banner=”12″] |
(SecurityAffairs – VMWare, hacking)
[adrotate banner=”5″]
[adrotate banner=”13″]
Text extracted automatically; images, tables and formatting may be missing. Original: https://securityaffairs.com/101805/security/vmware-vcenter-server-issue-details.html