Actively exploited · Published Aug 16, 2021 · Assigned by mitre
CVE-2021-35395
Critical 9.8 Exploited
In plain English
A critical-severity security flaw in AP-Router SDK from Realtek. Attackers are actively exploiting it in the wild (listed by CISA on November 3, 2021). The chance it is exploited in the next 30 days is estimated at 98.1% (higher than 99.9% of all known vulnerabilities). Ready-made attack tooling exists: Nuclei. Apply updates per vendor instructions.
CISA guidance
Apply updates per vendor instructions.
Federal agencies must remediate by Nov 17, 2021.
Official description
Realtek Jungle SDK version v2.x up to v3.4.14B provides an HTTP web server exposing a management interface that can be used to configure the access point. Two versions of this management interface exists: one based on Go-Ahead named webs and another based on Boa named boa. Both of them are affected by these vulnerabilities. Specifically, these binaries are vulnerable to the following issues: - stack buffer overflow in formRebootCheck due to unsafe copy of submit-url parameter - stack buffer overflow in formWsc due to unsafe copy of submit-url parameter - stack buffer overflow in formWlanMultipleAP due to unsafe copy of submit-url parameter - stack buffer overflow in formWlSiteSurvey due to unsafe copy of ifname parameter - stack buffer overflow in formStaticDHCP due to unsafe copy of hostname parameter - stack buffer overflow in formWsc due to unsafe copy of 'peerPin' parameter - arbitrary command execution in formSysCmd via the sysCmd parameter - arbitrary command injection in formWsc via the 'peerPin' parameter Exploitability of identified issues will differ based on what the end vendor/manufacturer did with the Realtek SDK webserver. Some vendors use it as-is, others add their own authentication implementation, some kept all the features from the server, some remove some of them, some inserted their own set of features. However, given that Realtek SDK implementation is full of insecure calls and that developers tends to re-use those examples in their custom code, any binary based on Realtek SDK webserver will probably contains its own set of issues on top of the Realtek ones (if kept). Successful exploitation of these issues allows remote attackers to gain arbitrary code execution on the device.
Affected products (as reported)
References
- https://www.realtek.com/en/cu-1-en/cu-1-taiwan-en x_refsource_MISC
- https://www.realtek.com/images/safe-report/Realtek_APRouter_SDK_Advisory-CVE-2021-35392_35395.pdf x_refsource_MISC
- https://www.iot-inspector.com/blog/advisory-multiple-issues-realtek-sdk-iot-supply-chain x_refsource_MISC
- https://www.cisa.gov/known-exploited-vulnerabilities-catalog?field_cve=CVE-2021-35395 government-resource