Microsoft Internet Explorer Use-After-Free
CVE-2012-4969 is a high-severity use after free vulnerability in Internet Explorer from Microsoft, with a CVSS 3.1 base score of 8.1 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. Affected Internet Explorer versions: 6; 7; 8, and others listed below. The record does not name a fixed version, so check the vendor advisory. CISA added it to the Known Exploited Vulnerabilities catalogue on June 8, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Check which version of Internet Explorer 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 technet.microsoft.com 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 |
|---|---|---|---|
| Microsoft | Internet Explorer | 6; 7; 8; 9 | Not stated |
Version data comes from NVD's product matching. 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
- HighSuccess depends on conditions outside the attacker's control.
- Privileges required
- NoneNo account or login is needed.
- User interaction
- NoneNo action by a victim is required.
- 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:N/AC:H/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 8.1 | High | NVD |
| CVSS 3.1 | 8.1 | High | CISA (ADP) |
| CVSS 2.0 | 9.3 | High | NVD |
Official description
Use-after-free vulnerability in the CMshtmlEd::Exec function in mshtml.dll in Microsoft Internet Explorer 6 through 9 allows remote attackers to execute arbitrary code via a crafted web site, as exploited in the wild in September 2012.
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
- eromang.zataz.com/2012/09/16/zero-day-season-is-really-not-over-yet/Third Party Advisory
- kb.cert.org/vuls/id/480095Third Party Advisory, US Government Resource
- securitytracker.com/id?1027538Third Party Advisory, VDB Entry
- securityweek.com/new-internet-explorer-zero-day-being-exploited-wildThird Party Advisory
- us-cert.gov/cas/techalerts/TA12-255A.htmlThird Party Advisory, US Government Resource
- us-cert.gov/cas/techalerts/TA12-262A.htmlThird Party Advisory, US Government Resource
- us-cert.gov/cas/techalerts/TA12-265A.htmlThird Party Advisory, US Government Resource
- oval.cisecurity.org/repository/search/definition/oval%3Aorg.mitre.oval%3Adef%3A15729Third Party Advisory
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2012-4969US Government Resource
Other vulnerabilities in Internet Explorer
- 8.8 High severity
- 8.8 High severity
- 7.5 High severity
- 8.8 High severity
- 7.5 High severity
- 7.5 High severity
Recent Use After Free vulnerabilities
- 9.3 High severity
- 8.8 High severity
- 7.8 High severity
Adobe Acrobat and Reader Use-After-Free Exploited
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