CVE-2020-1711 – This vulnerability allows remote attackers to t... (How to Fix)

Q: What is the severity of CVE-2020-1711?

CVE-2020-1711 has a CVSS score of 7.7 (HIGH). This vulnerability allows remote attackers to trigger an out-of-bounds heap buffer access in QEMU's iSCSI Block driver, potentially causing denial of service or arbitrary code execution with QEMU process privileges. It affects QEMU versions 2.12.0 through 4.2.0 when using iSCSI storage. Organizations running virtualized environments with iSCSI storage are primarily affected.

📋 TL;DR

This vulnerability allows remote attackers to trigger an out-of-bounds heap buffer access in QEMU's iSCSI Block driver, potentially causing denial of service or arbitrary code execution with QEMU process privileges. It affects QEMU versions 2.12.0 through 4.2.0 when using iSCSI storage. Organizations running virtualized environments with iSCSI storage are primarily affected.

💻 Affected Systems

Products:

QEMU

Versions: 2.12.0 through 4.2.0

Operating Systems: Linux distributions with QEMU packages, Windows with QEMU

Default Config Vulnerable: ✅ No

Notes: Only vulnerable when using iSCSI block storage backend. Default QEMU configurations without iSCSI are not affected.

📦 What is this software?

⚠️ Risk & Real-World Impact

🔴

Worst Case

Remote code execution with QEMU process privileges on the host system, potentially leading to full host compromise and lateral movement within the virtualization environment.

🟠

Likely Case

Denial of service through QEMU process crash, disrupting virtual machines using iSCSI storage and causing service interruptions.

🟢

If Mitigated

Limited impact if iSCSI storage is not used or if network segmentation prevents access to iSCSI ports from untrusted networks.

🌐 Internet-Facing: MEDIUM - Requires iSCSI storage configuration and network exposure; not all QEMU deployments use iSCSI or expose it externally.

🏢 Internal Only: HIGH - Internal attackers or compromised systems could exploit this if iSCSI storage is used within the environment.

🎯 Exploit Status

Public PoC: ✅ No

Weaponized: UNKNOWN

Unauthenticated Exploit: ⚠️ Yes

Complexity: MEDIUM

Exploitation requires network access to iSCSI server and knowledge of iSCSI operations. No public exploit code was found in references.

🛠️ Fix & Mitigation

✅ Official Fix

Patch Version: QEMU 4.2.1 and later

Vendor Advisory: https://access.redhat.com/errata/RHSA-2020:0669

Restart Required: Yes

Instructions:

1. Update QEMU to version 4.2.1 or later. 2. For Red Hat systems: yum update qemu-kvm. 3. Restart all affected virtual machines and QEMU processes.

🔧 Temporary Workarounds

Disable iSCSI Storage

all

Remove or disable iSCSI block storage backends in QEMU configurations

Edit QEMU configuration files to remove '-drive file=iscsi://...' options
Replace iSCSI storage with local or other storage types

Network Segmentation

linux

Restrict network access to iSCSI ports (default TCP 3260) from untrusted networks

iptables -A INPUT -p tcp --dport 3260 -s trusted_network -j ACCEPT
iptables -A INPUT -p tcp --dport 3260 -j DROP

🧯 If You Can't Patch

Implement strict network segmentation to isolate iSCSI traffic to trusted networks only
Monitor for abnormal iSCSI traffic patterns and QEMU process crashes

🔍 How to Verify

Check if Vulnerable:

Check QEMU version: qemu-system-x86_64 --version | grep 'version' and verify if between 2.12.0 and 4.2.0. Check if iSCSI storage is configured.

Check Version:

qemu-system-x86_64 --version | head -1

Verify Fix Applied:

Verify QEMU version is 4.2.1 or later: qemu-system-x86_64 --version. Check that no regression in iSCSI functionality occurs.

📡 Detection & Monitoring

Log Indicators:

QEMU process crashes with segmentation faults
Abnormal iSCSI connection attempts in system logs
Kernel logs showing memory corruption errors

Network Indicators:

Unusual iSCSI traffic patterns to QEMU hosts
Multiple connection attempts to iSCSI port 3260

SIEM Query:

source="qemu.log" AND ("segmentation fault" OR "crash" OR "SIGSEGV") OR destination_port=3260 AND protocol="tcp" AND abnormal_volume

📊 Metadata

CVE ID: CVE-2020-1711

CVSS v3 Score: 7.7 (HIGH)

CVSS Vector: CVSS:3.1/AV:N/AC:H/PR:L/UI:N/S:C/C:L/I:L/A:H

CWE: CWE-122

Published: February 11, 2020

Last Updated: November 21, 2024

🔗 References

http://lists.opensuse.org/opensuse-security-announce/2020-04/msg00007.html Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0669 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0730 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0731 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0773 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-1711 Issue Tracking,Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/03/msg00017.html Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/09/msg00013.html Mailing List,Third Party Advisory
https://lists.gnu.org/archive/html/qemu-devel/2020-01/msg05535.html Mailing List,Patch,Third Party Advisory
https://security.gentoo.org/glsa/202005-02 Third Party Advisory
https://usn.ubuntu.com/4283-1/ Third Party Advisory
https://www.openwall.com/lists/oss-security/2020/01/23/3 Mailing List,Third Party Advisory
http://lists.opensuse.org/opensuse-security-announce/2020-04/msg00007.html Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0669 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0730 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0731 Third Party Advisory
https://access.redhat.com/errata/RHSA-2020:0773 Third Party Advisory
https://bugzilla.redhat.com/show_bug.cgi?id=CVE-2020-1711 Issue Tracking,Patch,Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/03/msg00017.html Third Party Advisory
https://lists.debian.org/debian-lts-announce/2020/09/msg00013.html Mailing List,Third Party Advisory
https://lists.gnu.org/archive/html/qemu-devel/2020-01/msg05535.html Mailing List,Patch,Third Party Advisory
https://security.gentoo.org/glsa/202005-02 Third Party Advisory
https://usn.ubuntu.com/4283-1/ Third Party Advisory
https://www.openwall.com/lists/oss-security/2020/01/23/3 Mailing List,Third Party Advisory

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