Critical Windows Exploit – Targeted by Ransomware

The WannaCry ransomware worm, aka WanaCypt0r aka WCry, today spread rapidly over the internet. The worm targets mainly machines in Russia, Ukraine, India and Taiwan initially. However it has a footprint in about 74 countries. Once infected, a machine will also attempt to infect other clients on the same local network. So if you have a machine infected, isolate it immediately to prevent it from spreading.

WannaCry is installed on Windows computers by a worm that spreads across networks by exploiting a vulnerability in Microsoft’s SMB file-sharing services. It specifically abuses a bug designated MS17-010 that Redmond patched in March for modern versions of Windows – unpatched systems, or ones running legacy versions such as Windows XP, are therefore vulnerable and can be attacked.

This was released back in April as part of a leak regarding NSA that publicize the bug and a tool used to exploit it. Hackers have now made use of the tool and strapped it to ransomware.

Further Details are below:

  • In March, Microsoft released a security update which addresses the vulnerability that these attacks are exploiting.
  • For customers using Windows Defender, Microsoft has released an update earlier today which detects this threat as Ransom:Win32/WannaCrypt. Make sure all antivirus / anti-malware software are up to date. Clients running anti-malware software from any number of security companies can confirm with their provider if they are protected.
  • Clients should consider blocking legacy protocols on their networks such as SMBv1.
  • Clients who do not need to mount to network shares should considered disabling by default the SMB service. For newer versions of Windows, you can specifically remove SMBv1 by removing the feature.
  • This impact systems as old as Windows XP. So all your machines including desktops could technically be at risk.

All our Managed Clients running Windows are already protected as we regularly update your system as patches become available.

If you have any questions regarding this exploit or how to implement some of the recommendations above, please feel free to open a ticket with our support: https://www.sprintserve.net/support.

CABundle for Comodo InstantSSL

If you are using Apache / Cpanel / WHM, you may have found that recently you are having issues installing certificates from Comodo InstantSSL.

When you order the certificate, you would receive your certificate in a zipped file, together with 3 other certificate files. Comodo do not really explained clearly how to use the files. In order to create the CABundle, you would need to add them in this order in one file:

AddTrustExternalCARoot.crt
COMODORSAAddTrustCA.crt
COMODORSADomainValidationSecureServerCA.crt

For your convenience, you can copy and paste the following instead:

-----BEGIN CERTIFICATE-----
MIIENjCCAx6gAwIBAgIBATANBgkqhkiG9w0BAQUFADBvMQswCQYDVQQGEwJTRTEU
MBIGA1UEChMLQWRkVHJ1c3QgQUIxJjAkBgNVBAsTHUFkZFRydXN0IEV4dGVybmFs
IFRUUCBOZXR3b3JrMSIwIAYDVQQDExlBZGRUcnVzdCBFeHRlcm5hbCBDQSBSb290
MB4XDTAwMDUzMDEwNDgzOFoXDTIwMDUzMDEwNDgzOFowbzELMAkGA1UEBhMCU0Ux
FDASBgNVBAoTC0FkZFRydXN0IEFCMSYwJAYDVQQLEx1BZGRUcnVzdCBFeHRlcm5h
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mk6vBbOmcZSccbNQYArHE504B4YCqOmoaSYYkKtMsE8jqzpPhNjfzp/haW+710LX
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6wwCURQtjr0W4MHfRnXnJK3s9EK0hZNwEGe6nQY1ShjTK3rMUUKhemPR5ruhxSvC
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mnkPIAou1Z5jJh5VkpTYghdae9C8x49OhgQ=
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
MIIFdDCCBFygAwIBAgIQJ2buVutJ846r13Ci/ITeIjANBgkqhkiG9w0BAQwFADBv
MQswCQYDVQQGEwJTRTEUMBIGA1UEChMLQWRkVHJ1c3QgQUIxJjAkBgNVBAsTHUFk
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BgNVBAcTB1NhbGZvcmQxGjAYBgNVBAoTEUNPTU9ETyBDQSBMaW1pdGVkMSswKQYD
VQQDEyJDT01PRE8gUlNBIENlcnRpZmljYXRpb24gQXV0aG9yaXR5MIICIjANBgkq
hkiG9w0BAQEFAAOCAg8AMIICCgKCAgEAkehUktIKVrGsDSTdxc9EZ3SZKzejfSNw
AHG8U9/E+ioSj0t/EFa9n3Byt2F/yUsPF6c947AEYe7/EZfH9IY+Cvo+XPmT5jR6
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PUsE2JOAWVrgQSQdso8VYFhH2+9uRv0V9dlfmrPb2LjkQLPNlzmuhbsdjrzch5vR
pu/xO28QOG8=
-----END CERTIFICATE-----
-----BEGIN CERTIFICATE-----
MIIGCDCCA/CgAwIBAgIQKy5u6tl1NmwUim7bo3yMBzANBgkqhkiG9w0BAQwFADCB
hTELMAkGA1UEBhMCR0IxGzAZBgNVBAgTEkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4G
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EkdyZWF0ZXIgTWFuY2hlc3RlcjEQMA4GA1UEBxMHU2FsZm9yZDEaMBgGA1UEChMR
Q09NT0RPIENBIExpbWl0ZWQxNjA0BgNVBAMTLUNPTU9ETyBSU0EgRG9tYWluIFZh
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HyaPs9Kg4DdbKDsx5Q5XLVq4rXmsXiBmGqW5prU5wfWYQ//u+aen/e7KJD2AFsQX
j4rBYKEMrltDR5FL1ZoXX/nUh8HCjLfn4g8wGTeGrODcQgPmlKidrv0PJFGUzpII
0fxQ8ANAe4hZ7Q7drNJ3gjTcBpUC2JD5Leo31Rpg0Gcg19hCC0Wvgmje3WYkN5Ap
lBlGGSW4gNfL1IYoakRwJiNiqZ+Gb7+6kHDSVneFeO/qJakXzlByjAA6quPbYzSf
+AZxAeKCINT+b72x
-----END CERTIFICATE-----

 

If you need any further information, as always please feel free to contact us.

How to check if a SSL Certificate is expired

Have you ever wondered how you can check the validity of a certain SSL certificate from shell / SSH? There is an useful script that we typically use on our end. If the location provided below is no longer available, please feel free to contact us as we have a copy.

wget http://prefetch.net/code/ssl-cert-check -O /PATH/TO/SAVE/FILE

Replace “/PATH/TO/SAVE/FILE” wieth your own preferred path of choice e.g. “/usr/local/src/ssl-cert-check”. We will now use this path in our example.

cd /usr/local/src/
chmod +x ssl-cert-check
./ssl-cert-check -c /PATH/TO/SSL/YOURDOMAIN.CRT

The script will output whether the certificate is still valid. Enjoy.

How to secure SSH

In our work with clients, we do a lot of server management and security hardening on the servers before it’s released to the clients. One of the first things we typically work on is to ensure SSHd is secured. The reason is that any kernel root exploit will be made easier with shell access.

This tutorial is not meant to be all encompassing, although we will cover a few key areas. We will use Redhat / CentOS Linux distribution as an example and file paths will vary depending on the distribution. We will also use “nano” as the text editor in the examples.

Change the SSH port

While security by obscurity is heavily criticized in some quarters, the truth is due to the time taken to scan all the ports, unless it’s a targeted attack, this step should immediately stop scanners dead in their tracks.

nano /etc/ssh/sshd_config

Change:

#Port 22

to (Replace “NEW_PORT” with your port of choice)

Port <NEW_PORT>

Allow only strong protocols

Version 1 of the SSH protocol has many weaknesses, of which it’s out of scope of this article to discuss. But we will be disabling it.
Change:

#Protocol 2,1"

to

Protocol 2

Allow only strong protocols

Version 1 of the SSH protocol has many weaknesses, of which it’s out of scope of this article to discuss. But we will be disabling it.
Change:

#Protocol 2,1"

to

Protocol 2

Disable Password Authentication

We advise that you consider using only key authentication with your server. This means that even if someone someone get your password, your server will continue to be secure. If you are unsure about how to generate a SSH keypair, do refer to our quick tip here.

Change:

#PasswordAuthentication yes

to

PasswordAuthentication no

On top of that, you would need to disable direct root login:

Change:

#PermitRootLogin yes

to

PermitRootLogin without-password

 

Restart SSHd:

/etc/init.d/sshd restart

Enjoy better SSH security!

How to generate SSH keypairs

We will be using Redhat / CentOS conventions in our examples in terms of the file paths.

Generate the Key Pair

ssh-keygen -t rsa -b 2048

This should generate the files in ~/.ssh/, “id_rsa” and “id_rsa.pub”

id_rsa is your private key and should NEVER be given out. id_rsa.pub is your public key which can be freely shared.

Enjoy better security!

Reclaiming space from PHP error logs

If you ever have a Cpanel server running after a while, you would notice invariably that most of the accounts or users will have accumulated error logs within their home directories. When you have a running server for a while, this can take up many GB. Here’s a quick way to reclaim some space:

find /home/ -name error_log  -exec rm -rf {} \;

Enjoy some extra space!