Experts published PoC exploits for CVE-2020-0796 privilege escalation flaw on Windows
Vulnerabilities mentionedAll →
| CVE | Vulnerability | CVSS | EPSS | Flags | Affected | Exposure | Published |
|---|---|---|---|---|---|---|---|
| CVE-2020-0796 | Unauthenticated RCE in Microsoft SMBv3 (SMBGhost) CVE-2020-0796 ('SMBGhost') is a memory-corruption (CWE-119) flaw in Microsoft's Server Message Block 3.1.1 (SMBv3) implementation, in which certain crafted requests — notably malformed compressed SMBv3 messages — can corrupt memory on the target. An unauthenticated remote attacker can trigger it by sending specially crafted SMBv3 packets directly to any SMB-enabled host, with no credentials or user interaction required. Successful exploitation yields arbitrary code execution on the target server or client, giving the attacker full control of the host, and the flaw was widely characterized as wormable because a compromised host can then attack others. Any Windows system running SMBv3 is affected — SMBv3 is enabled by default on modern Windows 10 and Windows Server builds, with Windows 10 versions 1903/1909 and Windows Server 2019/versions 1903/1909 identified in Microsoft's advisory. Exploitation is confirmed in the wild: the CVE is in CISA KEV (added 2022-02-10) with known ransomware use, EPSS assigns a 99.8% probability of exploitation within 30 days (100th percentile), and no public PoC is listed in the source data. Do: Apply Microsoft's updates per vendor instructions immediately, prioritizing Windows 10 1903/1909 and Windows Server 2019/1903/1909 hosts and anything with SMB (TCP 445) reachable by untrusted networks. Until patched, disable SMBv3 compression per Microsoft's mitigation guidance (setting DisableCompression=1 under LanmanServer) and restrict inbound TCP 445 to trusted sources. Given confirmed ransomware use, hunt for post-exploitation activity on unpatched hosts. | 10.0 | 100% | KEV ransomware PoC ×2 |
| masstens of millions of Windows hosts with SMBv3 enabled; on the order of 1M+ hosts with SMB (TCP 445) exposed to the internet per public scans |
Full article407 words · extracted from securityaffairs.com · click to collapse
Researchers published proof-of-concept (PoC) exploits for the CVE-2020-0796 Windows flaw, tracked as SMBGhost, that can be exploited for local privilege escalation.
Researchers Daniel García Gutiérrez (@danigargu) and Manuel Blanco Parajón (@dialluvioso_) have published proof-of-concept (PoC) exploits for the CVE-2020-0796 Windows vulnerability, tracked as SMBGhost, that can be exploited by attackers for local privilege escalation.
Cybersecurity firms Kryptos Logic discovered roughly 48,000 servers vulnerable to SMBGhost attacks exposed online.
We've just finished our first internet wide scan for CVE-2020-0796 and have identified 48000 vulnerable hosts. We'll be loading this data into Telltale for CERTs and organisations to action. We're also working on a blog post with more details (after patch).
— Kryptos Logic (@kryptoslogic) March 12, 2020
On March 10, 2019, the IT giant accidentally leaked info on a security update for a wormable vulnerability in the Microsoft Server Message Block (SMB) protocol.
The issue is a pre-remote code execution flaw that resides in the Server Message Block 3.0 (SMBv3) network communication protocol.
Technical details of the CVE-2020-0796 vulnerability have been disclosed, but security firms Cisco Talos and Fortinet published a description of the issue on their websites.
The vulnerability is caused by an error in the way SMBv3 handles maliciously crafted compressed data packets, a remote, unauthenticated attacker could exploit the flaw to execute arbitrary code within the context of the application.
The CVE-2020-0796 vulnerability affects devices running Windows 10 Version 1903, Windows Server Version 1903 (Server Core installation), Windows 10 Version 1909, and Windows Server Version 1909 (Server Core installation). According to Fortinet other Microsoft versions should be affected.
Microsoft released the KB4551762 update for Windows 10, versions 1903 and 1909, and Windows Server 2019, versions 1903 and 1909.
Immediately after the disclosure of the flaw, security experts created PoC exploits to trigger DoS condition, but now cybersecurity firm ZecOps published technical details of the flaw and released a PoC for remote code execution. The PoC exploits could be exploited to escalate privileges to SYSTEM.
“The bug is an integer overflow bug that happens in the Srv2DecompressData function in the srv2.sys SMB server driver.” wrote the experts. “We managed to demonstrate that the CVE-2020-0796 vulnerability can be exploited for local privilege escalation. Note that our exploit is limited for medium integrity level, since it relies on API calls that are unavailable in a lower integrity level.”
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(SecurityAffairs – hacking, CVE-2020-0796)
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