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sreweekly/markdown/134/01-what-do-i-need-to-know-about-segmentsmack.md

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+# What Do I Need To Know about “SegmentSmack”
+
+- **期号**: SRE Weekly Issue #134（2018-08-12）
+- **作者**: Johannes B. Ullrich, PhD — SAN Technology Institute
+- **链接**: https://isc.sans.edu/forums/diary/What Do I Need To Know about SegmentSmack/23964/
+
+## 简介
+
+The big news this week is SegmentSmack, a denial of service vulnerability in the Linux kernel that allows an attacker to cause high CPU consumption. Linked is a SANS Technology Institute researcher’s summary of the attack. Other coverage:AWSAkamaiFastlyCERTUbuntuRedhat
+
+## 正文
+
+# [What Do I Need To Know about "SegmentSmack"](https://isc.sans.edu/forums/diary/What+Do+I+Need+To+Know+about+SegmentSmack/23964/)
+
+[3 comment(s)](https://isc.sans.edu/diary/What+Do+I+Need+To+Know+about+SegmentSmack/23964/#comments)
+
+"SegmentSmack" is yet another branded vulnerability, also known as CVE-2018–5390. It hit the "news" yesterday. Succesful exploitation may lead to a denial of service against a targeted system. At this point, not a lot is known about this vulnerability. But here are some highlights:
+
+- Linux Kernel 4.9 is vulnerable. Older versions are not vulnerable. However, some Linux distributions like RedHat ES 6 and 7 include the vulnerable code as they backported some of the 4.9 networking code into their kernels
+- An attacker should not be able to exploit this vulnerability using a spoofed IP address. The attacker needs to first establish a TCP connection which is very difficult with a spoofed address.
+- It is not known how much traffic the attacker will have to send. But likely not more than a user would send in a normal TCP connection.
+- The attack can be launched against any exposed TCP service (Web, Mail, DNS...)
+- The vulnerable functions, tcp_collapse_ofo_queue() and tcp_prune_ofo_queue(), are used to deal with reassembling TCP segments. This likely implies that an exploit would use many out of order or otherwise abnormal packets. But this is just a guess at this point.
+- If you are vulnerable, your best bet is to update. There is likely not much else you can do (e.g. firewall rules)
+
+You can find more details here: https://www.kb.cert.org/vuls/id/962459
+
+---
+
+Johannes B. Ullrich, Ph.D., Dean of Research, [SANS Technology Institute](https://sans.edu)
+
+[Twitter](https://jbu.me/164)|
+
+Keywords: 
+
+[3 comment(s)](https://isc.sans.edu/diary/What+Do+I+Need+To+Know+about+SegmentSmack/23964/#comments)
+
+Click 
+
+[HERE](https://www.sans.org/profiles/dr-johannes-ullrich)to learn more about classes Johannes is teaching for SANS
+  
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+[Diary Archives](https://isc.sans.edu/diaryarchive.html)
+
+## Comments
+
+## Anonymous
+
+## Aug 8th 2018
+
+8 years ago
+
+## Anonymous
+
+## Aug 10th 2018
+
+8 years ago
+
+## Anonymous
+
+## Aug 28th 2018
+
+8 years ago