Rapid7 Vulnerability & Exploit Database

Alpine Linux: CVE-2021-3711: Classic Buffer Overflow

Free InsightVM Trial No Credit Card Necessary
2024 Attack Intel Report Latest research by Rapid7 Labs
Back to Search

Alpine Linux: CVE-2021-3711: Classic Buffer Overflow

Severity
7
CVSS
(AV:N/AC:L/Au:N/C:P/I:P/A:P)
Published
08/24/2021
Created
04/09/2024
Added
03/26/2024
Modified
10/02/2024

Description

In order to decrypt SM2 encrypted data an application is expected to call the API function EVP_PKEY_decrypt(). Typically an application will call this function twice. The first time, on entry, the "out" parameter can be NULL and, on exit, the "outlen" parameter is populated with the buffer size required to hold the decrypted plaintext. The application can then allocate a sufficiently sized buffer and call EVP_PKEY_decrypt() again, but this time passing a non-NULL value for the "out" parameter. A bug in the implementation of the SM2 decryption code means that the calculation of the buffer size required to hold the plaintext returned by the first call to EVP_PKEY_decrypt() can be smaller than the actual size required by the second call. This can lead to a buffer overflow when EVP_PKEY_decrypt() is called by the application a second time with a buffer that is too small. A malicious attacker who is able present SM2 content for decryption to an application could cause attacker chosen data to overflow the buffer by up to a maximum of 62 bytes altering the contents of other data held after the buffer, possibly changing application behaviour or causing the application to crash. The location of the buffer is application dependent but is typically heap allocated. Fixed in OpenSSL 1.1.1l (Affected 1.1.1-1.1.1k).

Solution(s)

  • alpine-linux-upgrade-openssl
  • alpine-linux-upgrade-openssl3
  • alpine-linux-upgrade-openssl1.1-compat

With Rapid7 live dashboards, I have a clear view of all the assets on my network, which ones can be exploited, and what I need to do in order to reduce the risk in my environment in real-time. No other tool gives us that kind of value and insight.

– Scott Cheney, Manager of Information Security, Sierra View Medical Center

;