MikroTik RouterOS Stack-Based Buffer Overflow
CVE-2018-7445 is a critical-severity improper restriction of operations within the bounds of a memory buffer vulnerability in Routeros from MikroTik, with a CVSS 3.1 base score of 9.8 out of 10. It can be exploited remotely over the network by an unauthenticated attacker, without any action from a user. The record lists version 6.41.3 as the first without the flaw, so updating Routeros to that release or later removes the exposure. CISA added it to the Known Exploited Vulnerabilities catalogue on September 8, 2022, which means attacks have been observed in the wild.
Attackers are already exploiting this vulnerability, according to CISA.
What to do
- Update Routeros to 6.41.3 or a later version.
- CISA's required action: Apply updates per vendor instructions.
- Until you can update, restrict network access to the affected service so it is not reachable from untrusted networks.
Affected products and versions
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
- 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
- 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:L/PR:N/UI:N/S:U/C:H/I:H/A:H. Scored by NVD.
| Scoring system | Score | Severity | Scored by |
|---|---|---|---|
| CVSS 3.1 | 9.8 | Critical | NVD |
| CVSS 3.1 | 9.8 | Critical | CISA (ADP) |
| CVSS 2.0 | 10.0 | High | NVD |
Official description
A buffer overflow was found in the MikroTik RouterOS SMB service when processing NetBIOS session request messages. Remote attackers with access to the service can exploit this vulnerability and gain code execution on the system. The overflow occurs before authentication takes place, so it is possible for an unauthenticated remote attacker to exploit it. All architectures and all devices running RouterOS before versions 6.41.3/6.42rc27 are vulnerable.
Source: the CVE record as published by its numbering authority, via NVD and CVE.org.
The underlying weakness: Improper Restriction of Operations within the Bounds of a Memory Buffer
The product performs operations on a memory buffer, but it reads from or writes to a memory location outside the buffer's intended boundary.
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: yes, technical impact: total).
- Record last changed materially (score, affected products, status or references).
References
Third-party and government advisories
- securityfocus.com/bid/103427Third Party Advisory, VDB Entry
- cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2018-7445US Government Resource
Technical write-ups (may include proof of concept)
- seclists.org/fulldisclosure/2018/Mar/38Exploit, Mailing List, Third Party Advisory, VDB Entry
- coresecurity.com/advisories/mikrotik-routeros-smb-buffer-overflowExploit, Third Party Advisory
- exploit-db.com/exploits/44290/Exploit, Third Party Advisory, VDB Entry
Other vulnerabilities in Routeros
- 7.4 High severity
- 8.8 High severity
- 9.8 Critical severity
- 7.5 High severity
- 7.5 High severity
- 8.8 High severity
Recent Improper Restriction of Operations within the Bounds of a Memory Buffer vulnerabilities
- 7.8 High severity
Microsoft Office Memory Corruption Exploited
- 7.8 High severity
Microsoft Office Remote Code Execution Exploited
- 7.8 High severity
- 7.8 High severity
Linux Kernel PIE Stack Buffer Corruption Exploited
- 9.8 Critical severity
- 8.8 High severity
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