Source: cve@mitre.org
The software update mechanism as used in Bare Bones Software Yojimbo before 4.0, TextWrangler before 4.5.3, and BBEdit before 10.5.5 does not properly download and verify updates before installation, which allows attackers to perform "tampering or corruption" of the updates.
Critical vulnerability exists in Bare Bones Software's Yojimbo, TextWrangler, and BBEdit, allowing attackers to compromise software update mechanisms. This flaw permits attackers to inject malicious code during the update process, leading to system compromise and potential data theft.
Step 1: Target Identification: The attacker identifies a vulnerable user running Yojimbo, TextWrangler, or BBEdit.
Step 2: Network Interception (MITM) or Local File Tampering: The attacker either intercepts the network traffic during the update download process (MITM) or gains local access to the system and modifies the update files before the application attempts to download them.
Step 3: Malicious Payload Injection: The attacker replaces the legitimate update package with a malicious one containing a payload (e.g., a backdoor, malware, or a command execution script).
Step 4: Update Trigger: The user initiates a software update within the affected application.
Step 5: Unverified Download: The application downloads the attacker-controlled malicious update package.
Step 6: Installation without Verification: The application installs the malicious update without verifying its authenticity or integrity.
Step 7: Payload Execution: The malicious payload is executed with the privileges of the user running the application, leading to system compromise.
The vulnerability stems from a lack of secure download and verification of software updates. The affected applications fail to properly validate the integrity of downloaded update packages before installation. This allows an attacker to intercept the update process, substitute a malicious update package, and execute arbitrary code with the privileges of the user running the application. The root cause is the absence of cryptographic verification (e.g., digital signatures, checksums) to ensure the authenticity and integrity of the downloaded update files. Specifically, the software trusts the source of the update without verifying its contents, making it susceptible to man-in-the-middle (MITM) attacks or local file tampering.
While specific APT groups are not directly linked to this CVE, the nature of the vulnerability makes it attractive for any attacker seeking to gain persistent access or compromise a system. Malware authors could easily incorporate this into their attack chains. This vulnerability is not listed on the CISA KEV.
Monitor network traffic for unencrypted HTTP downloads from the update servers of Bare Bones Software applications.
Analyze application logs for update failures or unexpected behavior after updates.
Examine file system for suspicious files or modifications in the application's installation directory or temporary update directories.
Implement file integrity monitoring (FIM) to detect unauthorized changes to application files.
Monitor for unusual network connections originating from the affected applications.
Upgrade to the latest versions of Yojimbo, TextWrangler, and BBEdit (versions 4.0+, 4.5.3+, and 10.5.5+ respectively) to patch the vulnerability.
Implement a secure software update mechanism that verifies the integrity of downloaded updates using digital signatures or checksums.
Use HTTPS for all update downloads to prevent MITM attacks.
Implement certificate pinning to ensure the application only trusts updates from the legitimate update server.
Regularly scan systems for vulnerable software versions.
Educate users about the risks of software updates and the importance of verifying the source of updates.