A Vulnerability in GnuPG Libgcrypt Could Allow for Arbitrary Code Execution

ITS Advisory Number: 
2021-016
Date(s) Issued: 
Tuesday, February 9, 2021
Subject: 
A Vulnerability in GnuPG Libgcrypt Could Allow for Arbitrary Code Execution
Overview: 

A vulnerability has been discovered in GNU Libgcrypt, which could allow for arbitrary code execution. Libgcrypt is a generic cryptographic library offered as part of GNU Privacy Guard (GnuPG) software suite to provide building blocks for carrying out cryptographic tasks such as encrypting and signing data and communications. It is shipped with most Linux distributions including Ubuntu and Fedora. Successful exploitation of this vulnerability could result in arbitrary code execution in the context of the affected application. Depending on the privileges associated with the application, an attacker could install programs; view, change, or delete data; or create new accounts with full user rights. Failed exploitation could result in a denial-of-service condition.

 

THREAT INTELLIGENCE:

There are currently no reports of this vulnerability being exploited in the wild.

 

Systems Affected: 
  • GnuPG Libgcrypt 1.9.0
RISK
GOVERNMENT
Large and medium government entities: 
High
Small government entities: 
Medium
BUSINESS
Large and medium business entities: 
High
Small business entities: 
Medium
Home Users: 
Low
Description: 

A vulnerability has been discovered in GNU Libgcrypt, which could allow for arbitrary code execution. This vulnerability is a heap buffer overflow, which occurs due to a wrong assumption in the block buffer management code. To trigger the bug, an attacker can send the Libgcrypt library a block of booby-trapped data to decrypt. Once decrypted, the application would execute the malicious shellcode. No verification or signature is validated to prevent the running of unexpected or malicious instructions in decrypted data.

 

Successful exploitation of this vulnerability could result in arbitrary code execution in the context of the affected application. Depending on the privileges associated with the application, an attacker could install programs; view, change, or delete data; or create new accounts with full user rights. Failed exploitation could result in a denial-of-service condition.

 

Actions: 
  • Verify no unauthorized system modifications have occurred on the system before applying the patch.
  • After appropriate testing, immediately apply the patched version of libgcrypt to vulnerable systems.
  • Run all software as non-privileged user to diminish effects of successful attack.
  • Remind users not to visit un-trusted websites or follow links provided by unknown or un-trusted sources.
  • Inform and educate users regarding the threats posed by hypertext links contained in emails or attachments especially from un-trusted sources.
  • Apply the Principle of Least Privilege to all systems and services.