Adobe Flash Player Use-After-Free
CVE-2018-4878 is a high-severity use after free vulnerability in Adobe Flash Player before 28.0.0.161, with a CVSS 3.1 base score of 7.8 out of 10. It can be exploited with local access to the system by an unauthenticated attacker, but only if a user takes part, for example by opening a link or file. Affected Adobe Flash Player before 28.0.0.161 versions: Adobe Flash Player before 28.0.0.161. 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
- Update Flash Player to 28.0.0.161 or a later version.
- CISA's required action: The impacted product is end-of-life and should be disconnected if still in use.
- Read the advisory on helpx.adobe.com for workarounds and exact fixed builds.
- Because the attack needs a user to take part, warn users about unexpected links and files related to this product until it is patched.
Affected products and versions
| Vendor | Product | Affected versions | Fixed in |
|---|---|---|---|
| Adobe Flash Player before 28.0.0.161 | Adobe Flash Player before 28.0.0.161 | Adobe Flash Player before 28.0.0.161 | Not stated |
| Adobe | Flash Player | before 28.0.0.161 | 28.0.0.161 |
| Red Hat | Enterprise Linux Desktop | 6.0 | Not stated |
| Red Hat | Enterprise Linux Server | 6.0 | Not stated |
| Red Hat | Enterprise Linux Workstation | 6.0 | 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
- LocalThe attacker needs local access or must trick a user into running something.
- Attack complexity
- LowNo special conditions are needed; the attack works reliably.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- RequiredA user must take an action such as opening a file or link.
- Scope
- UnchangedImpact stays within the vulnerable component.
- 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:L/AC:L/PR:N/UI:R/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | NVD |
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
| CVSS 2.0 | 7.5 | High | NVD |
Official description
A use-after-free vulnerability was discovered in Adobe Flash Player before 28.0.0.161. This vulnerability occurs due to a dangling pointer in the Primetime SDK related to media player handling of listener objects. A successful attack can lead to arbitrary code execution. This was exploited in the wild in January and February 2018.
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
- CVE record published.
- Added to CISA's Known Exploited Vulnerabilities catalogue.
- Deadline for US federal agencies to remediate, set by CISA.
- CISA published its SSVC assessment (exploitation: active, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- blog.talosintelligence.com/2018/02/group-123-goes-wild.htmlTechnical Description, Third Party Advisory
- access.redhat.com/errata/RHSA-2018:0285Third Party Advisory
- blog.morphisec.com/flash-exploit-cve-2018-4878-spotted-in-the-wild-massive-malspam-campaignThird Party Advisory
- github.com/InQuest/malware-samples/tree/master/CVE-2018-4878-Adobe-Flash-DRM-UAF-0dayThird Party Advisory
- github.com/vysec/CVE-2018-4878Third Party Advisory
- threatpost.com/adobe-flash-player-zero-day-spotted-in-the-wild/129742/Third Party Advisory
- darkreading.com/threat-intelligence/adobe-flash-vulnerability-reappears-in-malicious-word-files/d/d-id/1331139Press/Media Coverage, Third Party Advisory
- fireeye.com/blog/threat-research/2018/02/attacks-leveraging-adobe-zero-day.htmlThird Party Advisory
- trendmicro.com/vinfo/us/security/news/vulnerabilities-and-exploits/north-korean-hackers-allegedly-exploit-ado…Technical Description, Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-4878Third Party Advisory, US Government Resource
Technical write-ups (may include proof of concept)
- securingtomorrow.mcafee.com/mcafee-labs/hackers-bypassed-adobe-flash-protection-mechanism/Exploit, Third Party Advisory
- exploit-db.com/exploits/44412/Exploit, Third Party Advisory, VDB Entry
Other references
- github.com/cisagov/vulnrichment/issues/196Issue Tracking
Recent Use After Free vulnerabilities
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Adobe Flash Player Use-After-Free Exploited
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- 9.8 Critical severity
Adobe Flash Player Use-After-Free Exploited
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