Pulse Connect Secure VPN authentication bypass enables remote code execution
Pulse Connect Secure VPN has authentication bypass vulnerabilities enabling remote code execution; active exploitation confirmed, patches now available as of May 2021.
Sourceipa.go.jp — open the original
What to check
- Applies to
- The 1 CVE named below. Whether you run an affected version is not assessed: check the versions the source lists.
- Exploitation
- CISA lists CVE-2021-22893 as exploited in the wild.
IPA Japan issued an alert regarding critical vulnerabilities in Pulse Connect Secure, a remote access VPN product. The vulnerabilities allow remote unauthenticated attackers to bypass authentication and execute arbitrary code on affected systems. At the time of initial disclosure on April 21, 2021, no patches were available and the vendor recommended applying temporary workarounds or suspending use of the product. Active exploitation was confirmed in the wild, though no domestic Japanese incidents had been reported at that time. As of May 6, 2021, the vendor released patches for all affected versions. The advisory emphasizes urgency given confirmed active exploitation and potential for widespread impact.
Affected versions include Pulse Connect Secure 9.0R3 and later, as well as 9.1R1 and later, though other versions may also be vulnerable. The temporary workaround involved importing an XML file to mitigate URL-based attacks and disable Windows File Share Browser and Pulse Secure Collaboration features. Organizations are strongly urged to apply the available patches or implement workarounds immediately.
Mentioned in this report
Detection guidance
Suspicious Shell Spawned by Pulse Connect Secure Web Process (Possible RCE Exploitation)
A behavioural hunt for the technique in general, not a signature for the CVEs this report names.
Detects a shell or scripting interpreter spawned as a child of the Pulse Connect Secure web-facing service process, consistent with post-exploitation command execution following an authentication-bypass RCE against the VPN appliance. Auto-generated starting point — validate and tune in your environment before deploying. IOC matches can false-positive on shared infrastructure and decay as adversary infrastructure rotates.
title: Suspicious Shell Spawned by Pulse Connect Secure Web Process
id: 38f47231-6c6e-516f-8411-f8b14311b059
status: experimental
description: 'Detects shell or interpreter processes (sh, bash, perl, python) spawned
by the Pulse Connect Secure web-facing service processes (e.g. httpd, dsagentd,
dspkginstall or similar dana-na web components). This is consistent with remote
code execution following exploitation of an unauthenticated RCE vulnerability in
Pulse Connect Secure such as those disclosed in April/May 2021.
'
references:
- https://www.ipa.go.jp
author: Vorant
tags:
- attack.t1190
- attack.initial-access
logsource:
category: process_creation
product: linux
detection:
selection:
ParentImage|contains:
- /home/webserver
- dana-na
- httpd
- dsagentd
Image|endswith:
- /sh
- /bash
- /dash
- /perl
- /python
- /python3
filter:
CommandLine|contains:
- healthcheck
- logrotate
condition: selection and not filter
falsepositives:
- Legitimate administrative or diagnostic scripts executed by appliance maintenance
tooling
- Vendor-supplied health-check or log rotation scripts invoking shell interpreters
level: high
Behavioural rules are generated from public reporting — validate in your environment before deploying.
Source reporting: https://www.ipa.go.jp/archive/security/security-alert/2021/alert20210421.html
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