Hancom Office 2020: Buffer Underwrite
CVE-2022-33896 is a high-severity buffer underwrite vulnerability in Hancom Office 2020 from Hancom, 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 Hancom Office 2020 versions: Hancom Office 2020 11.0.0.5357. The record does not name a fixed version, so check the vendor advisory. There is no confirmed exploitation so far. EPSS estimates a 0.53% chance of exploitation within 30 days, which is low compared with other CVEs.
High severity with no evidence of exploitation so far.
What to do
- Check which version of Hancom Office 2020 you run against the affected versions below, and install the vendor's latest release.
- 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 |
|---|---|---|---|
| Hancom | Hancom Office 2020 | Hancom Office 2020 11.0.0.5357 | 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 3.0 | 7.8 | High | CNA (cisco.com) |
Official description
A buffer underflow vulnerability exists in the way Hword of Hancom Office 2020 version 11.0.0.5357 parses XML-based office files. A specially-crafted malformed file can cause memory corruption by using memory before buffer start, which can lead to code execution. A victim would need to access a malicious file to trigger this vulnerability.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Buffer Underwrite
The product writes to a buffer using an index or pointer that references a memory location prior to the beginning of the buffer.
How developers prevent this class of flaw
- Choose a language that is not susceptible to these issues.
- All calculated values that are used as index or for pointer arithmetic should be validated to ensure that they are within an expected range.
Timeline
- CVE record published.
- CISA published its SSVC assessment (exploitation: poc, automatable: no, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Technical write-ups (may include proof of concept)
- talosintelligence.com/vulnerability_reports/TALOS-2022-1574Exploit, Third Party Advisory
Other vulnerabilities in Hancom Office 2020
- 8.5 High severity
- 7.8 High severity
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