Ivanti Pulse Connect Secure Use-After-Free
CVE-2021-22893 is a critical-severity use after free vulnerability in Pulse Connect Secure, with a CVSS 3.1 base score of 10.0 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Pulse Connect Secure versions: PCS 9.0R3 or above, PCS 9.1R1 and above. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on November 3, 2021, which means attacks have been observed in the wild, including in ransomware campaigns.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of Pulse Connect Secure you run against the affected versions below, and install the vendor's latest release.
- CISA's required action: Apply updates per vendor instructions.
- Read the advisory on blog.pulsesecure.net for workarounds and exact fixed builds.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Pulse Connect Secure | Pulse Connect Secure | PCS 9.0R3 or above, PCS 9.1R1 and above | Not stated |
| Ivanti | Connect Secure | 9.0; 9.1 | Not stated |
Version data comes from the organisation that assigned the CVE. Confirm against the vendor advisory before deciding you are unaffected.
How the severity score breaks down
- Attack vector
- NetworkCan be exploited remotely over a network, including the internet.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- Scope
- ChangedThe attack can reach beyond the vulnerable component into other systems.
- Confidentiality
- HighAll data handled by the component can be read.
- Integrity
- HighData or code can be modified at will.
- Availability
- HighThe component can be taken down completely.
Vector: CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:C/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 10.0 | Critical | NVD |
| CVSS 3.1 | 10.0 | Critical | CISA (ADP) |
| CVSS 2.0 | 7.5 | High | NVD |
Official description
Pulse Connect Secure 9.0R3/9.1R1 and higher is vulnerable to an authentication bypass vulnerability exposed by the Windows File Share Browser and Pulse Secure Collaboration features of Pulse Connect Secure that can allow an unauthenticated user to perform remote arbitrary code execution on the Pulse Connect Secure gateway. This vulnerability has been exploited in the wild.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Use After Free
The product reuses or references memory after it has been freed. At some point afterward, the memory may be allocated again and saved in another pointer, while the original pointer references a location somewhere within the new allocation. Any operations using the original pointer are no longer valid because the memory belongs to the code that operates on the new pointer.
How developers prevent this class of flaw
- Choose a language that provides automatic memory management.
- When freeing pointers, be sure to set them to NULL once they are freed. However, the utilization of multiple or complex data structures may lower the usefulness of this strategy.
Timeline
- CISA published its SSVC assessment (exploitation: active, automatable: yes, technical impact: total).
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- kb.cert.org/vuls/id/213092Third Party Advisory, US Government Resource
- fireeye.com/blog/threat-research/2021/04/suspected-apt-actors-leverage-bypass-techniques-pulse-secure-zero-da…Third Party Advisory
- kb.cert.org/vuls/id/213092US Government Resource
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-22893US Government Resource
Other vulnerabilities in Pulse Connect Secure
- 8.8 High severity
- 8.8 High severity
- 7.2 High severity
Pulse Connect Secure Code Injection Exploited
Recent Use After Free vulnerabilities
- 4.4 Medium severity
Samsung Mobile Devices Memory Corruption Exploited
- 8.8 High severity
Google Chromium Blink Use-After-Free Exploited
- 8.8 High severity
- 8.8 High severity
Google Chrome Media Use-After-Free Exploited
- 9.6 Critical severity
Google Chrome Use-After-Free Exploited
- 9.8 Critical severity
VMware ESXi OpenSLP Use-After-Free Exploited
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