Source: security@huntr.dev
vim is vulnerable to Out-of-bounds Read
Vim, a widely used text editor, suffers from an out-of-bounds read vulnerability, potentially allowing attackers to leak sensitive information or crash the application. This flaw could be exploited by crafting a malicious file that, when opened in Vim, triggers the vulnerability, leading to unauthorized data access or a denial-of-service condition.
Step 1: Payload Delivery: An attacker crafts a malicious file, potentially containing a specific file format or a carefully constructed sequence of characters designed to trigger the vulnerability.
Step 2: User Interaction: The victim opens the malicious file using Vim. This could be through direct user action (e.g., vim malicious_file.txt) or indirectly if Vim is used as a component of another application.
Step 3: Vulnerability Trigger: Vim's parsing or processing routines encounter the crafted input. Due to the out-of-bounds read vulnerability, the program attempts to access memory outside of the allocated buffer.
Step 4: Information Leakage/Crash: Depending on the memory contents and the nature of the read, the attacker can either leak sensitive information from memory or cause Vim to crash, resulting in a denial-of-service condition.
The vulnerability, CVE-2021-4193, stems from an out-of-bounds read within Vim's code. Specifically, the flaw resides in how Vim handles certain file formats or specific input sequences. When processing a crafted file, the program attempts to access memory outside the allocated buffer, leading to the read of unintended data. This is often triggered by malformed input that causes the program to miscalculate the size or location of data being accessed. The root cause is a lack of proper bounds checking or incorrect calculations related to memory offsets during file parsing or processing. This can result in the program reading data from memory locations it shouldn't, potentially revealing sensitive information or causing a crash.
There is no specific APT or malware directly linked to this CVE. However, given the widespread use of Vim, it is a potential target for various threat actors. The vulnerability's potential for information leakage makes it attractive for espionage campaigns. This CVE is not listed in the CISA KEV catalog.
Monitor file access logs for unusual activity, especially the opening of files from untrusted sources by Vim.
Analyze crash dumps or core files generated by Vim for signs of memory corruption or out-of-bounds reads.
Implement file integrity monitoring to detect changes to Vim's executable or related libraries.
Network traffic analysis: Look for unusual network activity originating from systems running Vim, especially after opening a suspicious file.
Use a file scanner to identify files with known malicious characteristics or patterns associated with the vulnerability.
Update Vim to the latest version. This is the primary and most effective mitigation.
Restrict the use of Vim to trusted users and environments.
Implement a robust file scanning and filtering system to prevent malicious files from reaching vulnerable systems.
Enforce least privilege principles, limiting the permissions of users who interact with Vim.
Regularly audit and monitor system logs for suspicious activity related to Vim.