CVE-2020-25705: High severity Linux Linux kernel vulnerability
A flaw in ICMP packets in the Linux kernel may allow an attacker to quickly scan open UDP ports. This flaw allows an off-path remote attacker to effectively bypass source port UDP randomization. Software that relies on UDP source port randomization are indirectly affected as well on the Linux Based Products (RUGGEDCOM RM1224: All versions between v5.0 and v6.4, SCALANCE M-800: All versions between v5.0 and v6.4, SCALANCE S615: All versions between v5.0 and v6.4, SCALANCE SC-600: All versions prior to v2.1.3, SCALANCE W1750D: v8.3.0.1, v8.6.0, and v8.7.0, SIMATIC Cloud Connect 7: All versions, SIMATIC MV500 Family: All versions, SIMATIC NET CP 1243-1 (incl. SIPLUS variants): Versions 3.1.39 and later, SIMATIC NET CP 1243-7 LTE EU: Version
Other sources
A flaw in the way reply ICMP packets are limited in the Linux kernel functionality was found that allows to quickly scan open UDP ports. This flaw allows an off-path remote user to effectively bypassing source port UDP randomization. The highest threat from this vulnerability is to confidentiality and possibly integrity, because software that relies on UDP source port randomization are indirectly affected as well.
As result of research work, Keyu Man reported that the ICMP rate limiter could be used by attackers to get useful signal (that for example could be used for the DNS poisoning attack). After considering what could be improved in kernel to prevent this, this patch suggested: https://github.com/torvalds/linux/commit/b38e7819cae946e2edf869e604
— Red Hat
In icmpglobalallow of icmp.c, there is a possible disclosure of UDP source ports due to a side channel information disclosure. This could lead to remote information disclosure with no additional execution privileges needed. User interaction is not needed for exploitation.
— OSV
Affected Software
Remediation
Recommended actions to resolve this vulnerability, in priority order.
- Upgrade
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redhat/kernel-rtto a version that resolves this vulnerability.Fixed in 0:3.10.0-1160.21.1.rt56.1158.el7 - Upgrade
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redhat/kernelto a version that resolves this vulnerability.Fixed in 0:3.10.0-1160.21.1.el7 - Upgrade
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redhat/kernelto a version that resolves this vulnerability.Fixed in 0:3.10.0-693.87.1.el7 - Upgrade
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redhat/kernelto a version that resolves this vulnerability.Fixed in 0:3.10.0-957.76.1.el7 - Upgrade
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redhat/kernelto a version that resolves this vulnerability.Fixed in 0:3.10.0-1062.49.1.el7 - Upgrade
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redhat/kernel-rtto a version that resolves this vulnerability.Fixed in 0:4.18.0-240.15.1.rt7.69.el8_3 - Upgrade
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redhat/kernelto a version that resolves this vulnerability.Fixed in 0:4.18.0-240.15.1.el8_3 - Upgrade
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redhat/kernelto a version that resolves this vulnerability.Fixed in 0:4.18.0-147.43.1.el8_1 - Upgrade
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redhat/kernel-rtto a version that resolves this vulnerability.Fixed in 0:4.18.0-193.46.1.rt13.96.el8_2 - Upgrade
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redhat/kernelto a version that resolves this vulnerability.Fixed in 0:4.18.0-193.46.1.el8_2 - Upgrade
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redhat/kernelto a version that resolves this vulnerability.Fixed in 5.10 - Upgrade
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Siemens SCALANCE SC-600 familyto a version that resolves this vulnerability.Fixed in 2.1.3 - Upgrade
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Siemens SIMATIC NET CP 1243-7 LTE EUto a version that resolves this vulnerability.Fixed in 3.3 - Upgrade
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Siemens SIMATIC NET CP 1243-7 LTE USto a version that resolves this vulnerability.Fixed in 3.3 - Upgrade
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Siemens Simatic CP 1242-7 GPRS Firmwareto a version that resolves this vulnerability.Fixed in 3.3 - Upgrade
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Siemens SIMATIC NET CP 1543-1to a version that resolves this vulnerability.Fixed in 3.0 - Upgrade
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Siemens SIMATIC NET CP 1545-1to a version that resolves this vulnerability.Fixed in 1.1 - Upgrade
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debian/linuxto a version that resolves this vulnerability.Fixed in 5.10.223-1Fixed in 5.10.234-1Fixed in 6.1.129-1Fixed in 6.1.133-1Fixed in 6.12.22-1 - Upgrade
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android/:linux_kernel:to a version that resolves this vulnerability.Fixed in :2021-04-05 - Upgrade
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Linux kernelto a version that resolves this vulnerability.Patch b38e7819cae946e2edf869e604 - Configuration
Drop ICMP destination-unreachable messages, for example with `iptables -I OUTPUT -p icmp --icmp-type destination-unreachable -j DROP`, then persist the rule with `service iptables save`. This rule is not recommended when the host is an IP forwarder/router.
Linux firewall ICMP destination-unreachable replies = disabled
Event History
Parent advisories
This vulnerability appears in the following advisories.
Frequently Asked Questions
What is the severity of CVE-2020-25705?
The severity of CVE-2020-25705 is classified as medium, given its potential for remote exploitation.
How do I fix CVE-2020-25705?
To fix CVE-2020-25705, upgrade to the patched kernel versions provided in the security advisories from your Linux distribution.
Which Linux distributions are affected by CVE-2020-25705?
CVE-2020-25705 primarily affects Red Hat Enterprise Linux and related distributions, including various versions of the Linux kernel.
Can CVE-2020-25705 be exploited remotely?
Yes, CVE-2020-25705 can be exploited by an off-path remote attacker to bypass UDP source port randomization.
What impact does CVE-2020-25705 have on applications using UDP?
Applications that rely on UDP source port randomization are indirectly affected by CVE-2020-25705, potentially exposing them to scanning or probing by attackers.