Microsoft Word Remote Code Execution
CVE-2012-2539 is a high-severity out-of-bounds write vulnerability in Office Compatibility Pack from Microsoft, with a CVSS 2.0 base score of 9.3 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. CISA added it to the Known Exploited Vulnerabilities catalogue on March 28, 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 Office Compatibility Pack 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 docs.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 | Office Compatibility Pack | Not specified in the record | Not stated |
| Microsoft | Office Web Apps | 2010 | Not stated |
| Microsoft | Office Word Viewer | Not specified in the record | Not stated |
| Microsoft | Sharepoint Server | 2010 | Not stated |
| Microsoft | Word | 2003; 2007; 2010 | 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
- Access vector
- NetworkCan be exploited remotely over a network.
- Access complexity
- MediumSome conditions must be met.
- Authentication
- NoneNo login is needed.
- Confidentiality
- CompleteAll data can be read.
- Integrity
- CompleteAny data can be modified.
- Availability
- CompleteThe system can be shut down completely.
Vector: AV:N/AC:M/Au:N/C:C/I:C/A:C. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 7.8 | High | CISA (ADP) |
| CVSS 2.0 | 9.3 | High | NVD |
Official description
Microsoft Word 2003 SP3, 2007 SP2 and SP3, and 2010 SP1; Word Viewer; Office Compatibility Pack SP2 and SP3; and Office Web Apps 2010 SP1 allow remote attackers to execute arbitrary code or cause a denial of service (memory corruption) via crafted RTF data, aka "Word RTF 'listoverridecount' Remote Code Execution Vulnerability."
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Out-of-bounds Write
The product writes data past the end, or before the beginning, of the intended buffer.
How developers prevent this class of flaw
- Use a language that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. For example, many languages that perform their own memory management, such as Java and Perl, are not subject to buffer overflows. Other languages, such as Ada and C#, typically provide overflow protection, but the protection can be disabled by the programmer. Be wary that a language's interface to native code may still be subject to overflows, even if the language itself is theoretically safe.
- Use a vetted library or framework that does not allow this weakness to occur or provides constructs that make this weakness easier to avoid. Examples include the Safe C String Library (SafeStr) by Messier and Viega, and the Strsafe.h library from Microsoft. These libraries provide safer versions of overflow-prone string-handling functions.
- Use automatic buffer overflow detection mechanisms that are offered by certain compilers or compiler extensions. Examples include: the Microsoft Visual Studio /GS flag, Fedora/Red Hat FORTIFY_SOURCE GCC flag, StackGuard, and ProPolice, which provide various mechanisms including canary-based detection and range/index checking. D3-SFCV (Stack Frame Canary Validation) from D3FEND discusses canary-based detection in detail.
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
- us-cert.gov/cas/techalerts/TA12-346A.htmlThird Party Advisory, US Government Resource
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2012-2539US Government Resource
Other vulnerabilities in Office Compatibility Pack
- 7.8 High severity
Microsoft Office Memory Corruption Exploited
- 8.8 High severity
Microsoft Office Memory Corruption Exploited
- 7.8 High severity
Microsoft Office Remote Code Execution Exploited
- 7.8 High severity
Microsoft Office Security Feature Bypass Exploited
- 7.8 High severity
Microsoft Office Memory Corruption Exploited
- 9.3 High severity
Microsoft PowerPoint Memory Corruption Exploited
Recent Out-of-bounds Write vulnerabilities
- 8.8 High severity
- 8.1 High severity
Adobe Flash Player Memory Corruption Exploited
- 9.8 Critical severity
- 9.8 Critical severity
Exim Heap-Based Buffer Overflow Exploited
- 7.8 High severity
- 7.8 High severity
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