Pulse Connect Secure zero-day exploited pre-patch
An actively exploited authentication-bypass and remote code execution flaw in Pulse Connect Secure VPN was disclosed before a vendor fix was available.
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 issued an alert on a vulnerability in Pulse Connect Secure, a widely used enterprise VPN appliance, that allows a remote unauthenticated attacker to bypass authentication and execute arbitrary code. At the time of initial disclosure (April 21, 2021) no patched version existed, and the vendor recommended workarounds or temporarily disabling the product. Exploitation in the wild had already been confirmed globally, though no domestic (Japan) victims were reported at publication time.
The advisory affects Pulse Connect Secure 9.0R3 and later, and 9.1R1 and later, noting that other versions may also be impacted. On May 6, 2021, the vendor released patches covering all affected versions; IPA updated guidance to recommend applying the fix rather than relying solely on the interim mitigation, which involved importing an XML workaround file that disabled Windows File Share Browser and Pulse Secure Collaboration features to reduce URL-based attack exposure.
Given the product's role as an internet-facing remote access gateway, unpatched systems present a high-value target for initial access into enterprise networks. Organizations using Pulse Connect Secure should prioritize verifying patch status and reviewing logs for signs of prior exploitation during the vulnerable window.
Mentioned in this report
Detection guidance
Suspicious Process Execution from Pulse Connect Secure Service
A behavioural hunt for the technique in general, not a signature for the CVEs this report names.
Detects arbitrary process spawning from Pulse Connect Secure application context, indicating successful exploitation and code execution on the 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 Process Execution from Pulse Connect Secure Service
description: Detects process creation originating from Pulse Connect Secure application
processes, indicating successful arbitrary code execution following exploitation
of CVE-2021-22893. Focuses on child processes spawned by the Pulse service that
are atypical for normal VPN gateway operations.
tags:
- attack.t1190
- attack.execution
logsource:
category: process_creation
product: windows
detection:
selection_parent:
ParentImage|contains:
- Pulse
- PulseSecure
- dsservice
selection_suspicious_child:
Image|endswith:
- \cmd.exe
- \powershell.exe
- \rundll32.exe
- \regsvcs.exe
- \csc.exe
filter_expected_parent:
ParentImage|contains: PulseSecure_Installer
condition: selection_parent and selection_suspicious_child and not filter_expected_parent
falsepositives:
- Pulse Connect Secure maintenance or diagnostic scripts spawning cmd.exe for system
checks
- Legitimate IT automation tools that interact with the Pulse service
level: high
id: ef4dab33-877e-52d8-8037-934fc7541e05
status: experimental
author: Vorant
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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