BlueKeep (CVE-2019-0708) is a security vulnerability that was discovered in Microsoft's Remote Desktop Protocol implementation, which allows for the possibility of remote code execution.

BlueKeep
CVE identifier(s)CVE-2019-0708
Date patched14 May 2019; 4 months ago (2019-05-14)[1]
DiscovererUK National Cyber Security Centre[2]
Affected softwarepre-Windows 8 versions of Microsoft Windows

First reported in May 2019, it is present in all unpatched Windows NT-based versions of Microsoft Windows from Windows 2000 through Windows Server 2008 R2 and Windows 7. Microsoft issued a security patch (including an out-of-band update for several versions of Windows that have reached their end-of-life, such as Windows XP) on 14 May 2019. On 13 August 2019, related BlueKeep security vulnerabilities, collectively named DejaBlue, were reported to affect newer Windows versions, including Windows 7 and all recent versions up to Windows 10 of the operating system, as well as the older Windows versions.[3] On 6 September 2019, a Metasploit exploit of the wormable BlueKeep security vulnerability was announced to have been released into the public realm.[4]

HistoryEdit

The BlueKeep security vulnerability was first noted by the UK National Cyber Security Centre[2] and, on 14 May 2019, reported by Microsoft. The vulnerability was named BlueKeep by computer security expert Kevin Beaumont on twitter. BlueKeep is officially tracked as: CVE-2019-0708 and is a "wormable" remote code execution vulnerability.[5][6]

Both the U.S. National Security Agency (who issued its own advisory on the vulnerability on 4 June 2019)[7] and Microsoft stated that this vulnerability could potentially be used by self-propagating worms, with Microsoft (based on a security researcher's estimation that nearly 1 million devices were vulnerable) saying that such a theoretical attack could be of a similar scale to EternalBlue-based attacks such as NotPetya and WannaCry.[8][9][7]

On the same day as the NSA advisory, researchers of the CERT Coordination Center disclosed a separate RDP-related security issue in Windows 10 May 2019 Update and Windows Server 2019, citing a new behaviour where RDP Network Level Authentication (NLA) login credentials are cached on the client system, and the user can re-gain access to their RDP connection automatically if their network connection is interrupted. Microsoft dismissed this vulnerability as being intended behaviour, and it can be disabled via Group Policy.[10]

As of 1 June 2019, no active malware of the vulnerability seems to be publicly known; however, undisclosed proof of concept (PoC) codes exploiting the vulnerability may be available.[8][11][12][13] On 1 July 2019, Sophos, a British security company, reported on a working example of such a PoC, in order to emphasize the urgent need to patch the vulnerability.[14][15][16] On 22 July 2019, more details of an exploit were purportedly revealed by a conference speaker from a Chinese security firm.[17] On 25 July 2019, computer experts reported that a commercial version of the exploit may be available.[18][19] On 31 July 2019, computer experts reported a significant increase in malicious RDP activity and warn, based on histories of exploits from similar vulnerabilities, that an active exploit of the BlueKeep vulnerability in the wild may be imminent.[20]

On 13 August 2019, related BlueKeep security vulnerabilities, collectively named DejaBlue, were reported to affect newer Windows versions, including Windows 7 and all recent versions of the operating system up to Windows 10, as well as the older Windows versions.[3]

On 6 September 2019, an exploit of the wormable BlueKeep security vulnerability was announced to have now been released into the public realm.[4]

MechanismEdit

The RDP protocol uses "virtual channels", configured pre-authentication, as a data path between the client and server for providing extensions. RDP 5.1 defines 32 "static" virtual channels, and "dynamic" virtual channels are contained within one of these static channels. If a server binds the virtual channel "MS_T120" (a channel for which there is no legitimate reason for a client to connect to) with a static channel other than 31, heap corruption occurs that allows for arbitrary code execution at the system level.[21]

Windows XP, Windows Vista, Windows 7, Windows Server 2003, Windows Server 2008, and Windows Server 2008 R2 were named by Microsoft as being vulnerable to this attack. Versions newer than 7, such as Windows 8 and Windows 10, are not affected. The Cybersecurity and Infrastructure Security Agency stated that it had also successfully achieved code execution via the vulnerability on Windows 2000.[22]

MitigationEdit

Microsoft released patches for the vulnerability on 14 May 2019, for Windows XP, Windows Vista, Windows 7, Windows Server 2003, Windows Server 2008, and Windows Server 2008 R2. This included versions of Windows that are end-of-life (such as Vista, XP, and Server 2003) and no longer eligible for security updates.[8] The patch forces the aforementioned "MS_T120" channel to always be bound to 31 even if requested otherwise by an RDP server.[21]

The NSA recommended additional measures, such as disabling Remote Desktop Services and its associated port (TCP 3389) if it is not being used, and requiring Network Level Authentication (NLA) for RDP.[23] According to computer security company Sophos, two-factor authentication may make the RDP issue less vulnerable. However, the best protection is to take RDP off the Internet: switch RDP off if not needed and, if needed, make RDP accessible only via a VPN.[24]

See alsoEdit

ReferencesEdit

  1. ^ Foley, Mary Jo (2019-05-14). "Microsoft patches Windows XP, Server 2003 to try to head off 'wormable' flaw". ZDNet. Retrieved 2019-06-07.
  2. ^ a b Microsoft (May 2019). "Security Update Guide - Acknowledgements, May 2019". Microsoft. Retrieved 2019-06-07.
  3. ^ a b Greenberg, Andy (2019-08-13). "DejaBlue: New BlueKeep-Style Bugs Renew The Risk Of A Windows worm". Wired. Retrieved 2019-08-13.
  4. ^ a b Goodin, Dan (2019-09-06). "Exploit for wormable BlueKeep Windows bug released into the wild - The Metasploit module isn't as polished as the EternalBlue exploit. Still, it's powerful". Ars Technica. Retrieved 2019-09-06.
  5. ^ "Customer guidance for CVE-2019-0708 - Remote Desktop Services Remote Code Execution Vulnerability". Microsoft. 2019-05-14. Retrieved 2019-05-29.
  6. ^ "CVE-2019-0708 Remote Desktop Services Remote Code Execution Vulnerability - Security Vulnerability". Microsoft. 2019-05-14. Retrieved 2019-05-28.
  7. ^ a b Cimpanu, Catalin. "Even the NSA is urging Windows users to patch BlueKeep (CVE-2019-0708)". ZDNet. Retrieved 2019-06-20.
  8. ^ a b c Goodin, Dan (2019-05-31). "Microsoft practically begs Windows users to fix wormable BlueKeep flaw". Ars Technica. Retrieved 2019-05-31.
  9. ^ Warren, Tom (2019-05-14). "Microsoft warns of major WannaCry-like Windows security exploit, releases XP patches". The Verge. Retrieved 2019-06-20.
  10. ^ "Microsoft dismisses new Windows RDP 'bug' as a feature". Naked Security. 2019-06-06. Retrieved 2019-06-20.
  11. ^ Whittaker, Zack (2019-05-31). "Microsoft warns users to patch as exploits for 'wormable' BlueKeep bug appear". TechCrunch. Retrieved 2019-05-31.
  12. ^ O'Neill, Patrick Howell (2019-05-31). "You Need to Patch Your Older Windows PCs Right Now to Patch a Serious Flaw". Gizmodo. Retrieved 2019-05-31.
  13. ^ Winder, Davey (2019-06-01). "Microsoft Issues 'Update Now' Warning To Windows Users". Forbes. Retrieved 2019-06-01.
  14. ^ Palmer, Danny (2019-07-02). "BlueKeep: Researchers show how dangerous this Windows exploit could really be - Researchers develop a proof-of-concept attack after reverse engineering the Microsoft BlueKeep patch". ZDNet. Retrieved 2019-07-02.
  15. ^ Stockley, Mark (2019-07-01). "RDP BlueKeep exploit shows why you really, really need to patch". NakedSecurity.com. Retrieved 2019-07-01.
  16. ^ Staff (2019-05-29). "CVE-2019-0708: Remote Desktop Services remote code execution vulnerability (known as BlueKeep) - Technical Support Bulletin". Sophos. Retrieved 2019-07-02.
  17. ^ Goodin, Dan (2019-07-22). "Chances of destructive BlueKeep exploit rise with new explainer posted online - Slides give the most detailed publicly available technical documentation seen so far". Ars Technica. Retrieved 2019-07-23.
  18. ^ Cimpanu, Catalin (2019-07-25). "US company selling weaponized BlueKeep exploit - An exploit for a vulnerability that Microsoft feared it may trigger the next WannaCry is now being sold commercially". ZDNet. Retrieved 2019-07-25.
  19. ^ Franceschi-Bicchieral, Lorenzo (2019-07-26). "Cybersecurity Firm Drops Code for the Incredibly Dangerous Windows 'BlueKeep' Vulnerability - Researchers from U.S. government contractor Immunity have developed a working exploit for the feared Windows bug known as BlueKeep". Vice. Retrieved 2019-07-26.
  20. ^ Rudis, Bob (2019-07-31). "BlueKeep Exploits May Be Coming: Our Observations and Recommendations". RapidFire7.com. Retrieved 2019-08-01.
  21. ^ a b "RDP Stands for "Really DO Patch!" – Understanding the Wormable RDP Vulnerability CVE-2019-0708". McAfee Blogs. 2019-05-21. Retrieved 2019-06-19.
  22. ^ Tung, Liam. "Homeland Security: We've tested Windows BlueKeep attack and it works so patch now". ZDNet. Retrieved 2019-06-20.
  23. ^ Cimpanu, Catalin. "Even the NSA is urging Windows users to patch BlueKeep (CVE-2019-0708)". ZDNet. Retrieved 2019-06-20.
  24. ^ Stockley, Mark (2019-07-17). "RDP exposed: the wolves already at your door". Sophos. Retrieved 2019-07-17.

External linksEdit