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SonicWall Urges Users to Patch Several Vulnerabilities in Secure Mobile Access Products (CVE-2021-20038)

SonicWall patched eight vulnerabilities in its Secure Mobile Access 100 product line. None have been exploited in the wild, yet, but users are strongly urged to patch.

Background

On December 7, SonicWall issued an advisory (SNWLID-2021-0026) for eight CVEs in its Secure Mobile Access (SMA) 100 product line of remote access gateways. As part of the advisory, SonicWall “strongly urges” its customers to patch these vulnerabilities in the SMA 200, 210, 400, 410 and 500v products, in addition to SMA 100 series appliances with the Web Application Firewall (WAF) enabled.

CVEDescriptionCVSSv3
CVE-2021-20038Unauthenticated stack-based buffer overflow9.8
CVE-2021-20039Authenticated command injection7.2
CVE-2021-20040Unauthenticated file upload path traversal6.5
CVE-2021-20041Unauthenticated CPU exhaustion7.5
CVE-2021-20042Unauthenticated confused deputy6.3
CVE-2021-20043Heap-based buffer overflow8.8
CVE-2021-20044Post-authentication remote code execution7.2
CVE-2021-20045Multiple unauthenticated heap- and stack-based buffer overflows9.4

While there is no evidence at this time that these vulnerabilities have been exploited in the wild, SonicWall SMA devices have been targeted by threat actors in the past. In January, “highly sophisticated threat actors” exploited CVE-2021-20016, a critical SQL injection vulnerability in SMA100 devices. In July, SonicWall warned of an imminent ransomware attack leveraging known, patched vulnerabilities in SMA 100 products. The Cybersecurity and Infrastructure Security Agency also issued an alert about this campaign, confirming active attacks. It was later reported that the known flaw exploited in the campaign was CVE-2019-7481.

Analysis

The most severe of these flaws are a set of unauthenticated heap- and stack-based buffer overflow vulnerabilities. CVE-2021-20038 covers a single vulnerability and received a CVSSv3 score of 9.8, while CVE-2021-20045 covers multiple vulnerabilities, the bundle received at CVSSv3 score of 9.4. CVE-2021-20038 is the result of using strcat() function when handling environment variables from the HTTP GET method used in the SMA SSLVPN Apache httpd server. CVE-2021-20043 is also a heap-based buffer overflow and it received a CVSSv3 score of 8.8, but it requires authentication to exploit. For all three of these CVEs, successful exploitation would result in code execution as the “nobody” user in the SMA100 appliance.

The remaining flaws include a mix of authenticated and unauthenticated vulnerabilities ranging in severity from CVSSv3 6.3 to 7.5. Devices with the web application firewall enabled are still vulnerable to these flaws. Discovery of these vulnerabilities is credited to Jacob Baines of Rapid7 and Richard Warren of NCCGroup.

Proof of concept

At the time of publication, no proofs-of-concept have been published for any of these vulnerabilities.

Solution

SonicWall strongly urges users to update these devices. The advisory includes a guide for the impacted and fixed firmware versions.

Impacted ProductsImpacted VersionsFixed Versions
SMA 100 Series: SMA 200, 210, 400, 410, 500v9.0.0.11-31sv* and earlier, 10.2.0.8-37sv, 10.2.1.1-19sv, 10.2.1.2-24sv and earlier10.2.0.9-41sv, 10.2.1.3-27sv

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