Critical ScreenOS Security Flaw

Critical ScreenOS Security Flaw:
6.2.0r15 through 6.2.0r18 and
6.3.0r12 through 6.3.0r20.

Update 4/6/2016: New ScreenOS 6.3r22 release

Juniper has now completed the ScreenOS VPN updates with the removal of the DUAL_EC_DRBG and the ANSI X9.31 PRNG in ScreenOS 6.3r22…

Plan on downloading and updating systems accordingly.

Critical ScreenOS Security Flaw

To my friends running ScreenOS from Juniper, please review this critical security notice.

These issues can affect any product or platform running ScreenOS 6.2.0r15 through 6.2.0r18 and 6.3.0r12 through 6.3.0r20.  The first issue allows unauthorized remote administrative access to the device over SSH or telnet. Exploitation of this vulnerability can lead to complete compromise of the affected system.  The second issue may allow a knowledgeable attacker to decrypt encrypted VPN traffic.


Remember to read the new signing key warnings.  Your hardware may need the new signing key installed prior to upgrade to boot properly from the new images.


Upgrade procedure


1-Download the new signing key from the Juniper support site

  • Expand the zip file
  • Verify the signing key checksum

example on linux

$ md5sum imagekey.cer

99def4b80b75ed65aad52a5fc3ed1131  imagekey.cer

Mac OSX use:

$ md5 imagekey.cer

MD5 (imagekey.cer) = 99def4b80b75ed65aad52a5fc3ed1131

Thanks to Ryan in the comments.  Windows 7 hash check per:

Get-FileHash imagekey.cer -Algorithm MD5

Other Windows you will need to download a check sum utility like this one from MS others are also available

2-Download the ScreenOS Image 6.3R21 from the Support site

  • Expand the zip file
  • Verify the ScreenOS file checksum

MD5: 1974c20ed045b4de908a01221db63684

Upgrade procedure:

1-Pull a fresh configuraiton backup on all your devices to be sure you have a solid recovery point in case there are issues.

  • Configuration > Update > Conifg File

Choose: Save to file

2-On the CLI verify which signing key is currently on the device.  The new and correct signing key for ScreenOS 6.3R21 begins with  308201ad as shown below.

If the key begins with 308201ac then you MUST UPDATE THE IMAGE KEY BEFORE UPGRADING THE DEVICE.

ssg5-serial-> exec pki test skey

exec pki test <skey>.

Flash base = 0x51000000, Flash end = 0x0, sector size= 0x4000

KEY1  N/A len =433

 308201ad02010002818100fd7f53811d75122952df4a9c2eece4e7f611b7523cef4400c31e3f80b651 magic1 = f7e9294b magic2=0

KEY2  N/A len =433

 308201ad02010002818100fd7f53811d75122952df4a9c2eece4e7f611b7523cef4400c31e3f80b651 magic1 = f7e9294b magic2=0

KEY3  N/A len =433

 308201ad02010002818100fd7f53811d75122952df4a9c2eece4e7f611b7523cef4400c31e3f80b651 magic1 = f7e9294b magic2=0

2-Upgrade the Image key:  (if required)

  • Configuration > Update > ScreenOS/Keys

Select the Image Signature Key update radio button

Choose file: the imagekey.cer

Select Apply button

3-Upgrade ScreenOS:

  • Configuration > Update > ScreenOS/Keys

Select the Firmware Update radio button

Choose file: ssg5ssg20.6.3.0r21.0

Select Apply

The file will upload showing progress on the lower left

When complete it will apply and reboot taking about 5-10 minutes

3-When the device is available login and confirm the upgrade

Error: Bogus image – not authenticated!!!

This error will occur if you upgrade to the new ScreenOS image and still have the OLD signing key on your device.  The boot screen on the console port will show this message:

********Invalid image!!!
********Bogus image – not authenticated!!!

Fips check failed

To recover from this error and allow the device to boot you need to delete the signing key.

delete crypto auth-key

Then reboot the device and the new ScreenOS should load.


Security notice

Signing Key Articles

Originally Posted December 20, 2015
Last Revised on July 02, 2016