Severity: Unknown
Description: Das U-Boot is a device bootloader that can read its configuration from an AES encrypted file. For devices utilizing this environment encryption mode, U-Boot's use of a zero initialization vector may allow attacks against the underlying cryptographic implementation and allow an attacker to decrypt the data. Das U-Boot's AES-CBC encryption feature uses a zero (0) initialization vector. This allows an attacker to perform dictionary attacks on encrypted data produced by Das U-Boot to learn information about the encrypted data.
CVSS Score: N/A
D
No data available.
No data available.
1. Risk Assessment
The vulnerability CVE-2017-3225 concerns the use of a zero initialization vector (IV) in the AES-CBC encryption implementation within Das U-Boot, a widely used device bootloader. This allows attackers performing dictionary attacks against the encrypted configuration data. The vulnerability’s nature is cryptographic weakness, specifically a predictable IV. The business impact can range from minor inconvenience to significant data compromise, depending on the sensitivity of the data stored in the encrypted configuration. Likelihood of exploitation is moderate, as it requires access to the encrypted configuration file and some computational resources for the dictionary attack, but the attack is relatively straightforward. Ease of exploitation is also moderate; while a dictionary attack isn’t trivial, it's well-understood and doesn’t require complex exploit development. Potential impacts include loss of confidentiality of the U-Boot configuration, potentially revealing sensitive information like boot parameters, device settings, or even embedded credentials. Integrity could be impacted if the attacker can modify the configuration after decryption. Availability impacts are less direct, but a compromised configuration could lead to boot failures or unexpected device behavior. The EPSS score of 0.000500000 indicates a relatively low, but non-negligible risk, suggesting the vulnerability is present in a significant number of systems.
2. Potential Attack Scenarios
An attacker with physical access to a device running a vulnerable version of U-Boot can extract the encrypted configuration file. This could be done through various methods like accessing the file system directly, or via a network connection if the device exposes the file remotely. Once extracted, the attacker can use a dictionary attack to decrypt the configuration data. The dictionary attack would involve trying common keys or configurations until a plausible decryption is found. If the configuration contains sensitive information, such as network settings or device credentials, the attacker can leverage this information to gain further access to the device or the network it’s connected to. For example, if the encrypted configuration contains Wi-Fi passwords, the attacker could connect to the same network. If the configuration contains a root password, the attacker could gain full control of the device. The success of the attack depends on the complexity of the encrypted configuration and the effectiveness of the dictionary used.
3. Mitigation Recommendations
The primary mitigation for CVE-2017-3225 is to upgrade U-Boot to a version later than 2017.09. This update addresses the zero initialization vector issue and uses a more robust IV generation method. This is the most effective way to eliminate the vulnerability. Check with your device vendor for the latest U-Boot version compatible with your hardware. If patching immediately isn’t possible, consider restricting access to the encrypted configuration file to minimize the attack surface. Implement stronger access controls on the device to reduce the likelihood of an attacker gaining access to the configuration file. Further information can be found at SecurityFocus: http://www.securityfocus.com/bid/100675 and CERT: https://www.kb.cert.org/vuls/id/166743.
4. Executive Summary
CVE-2017-3225 is a vulnerability in the Das U-Boot bootloader that allows attackers to potentially decrypt configuration data due to the use of a predictable initialization vector in its AES-CBC encryption. This could expose sensitive information such as device settings, network configurations, and potentially even embedded credentials. While the risk is moderate, the potential impact could be significant, leading to compromised devices or network access. The recommended action is to upgrade U-Boot to version 2017.09 or later. Addressing this vulnerability is crucial to protect the confidentiality and integrity of devices utilizing U-Boot, and minimizing the potential for disruption or data compromise. Prompt patching and access control implementation will reduce the likelihood of exploitation and safeguard your systems.
Severity: Unknown
Description: Das U-Boot is a device bootloader that can read its configuration from an AES encrypted file. Devices that make use of Das U-Boot's AES-CBC encryption feature using environment encryption (i.e., setting the configuration parameter CONFIG_ENV_AES=y) read environment variables from disk as the encrypted disk image is processed. An attacker with physical access to the device can manipulate the encrypted environment data to include a crafted two-byte sequence which triggers an error in environment variable parsing. This error condition is improperly handled by Das U-Boot, resulting in an immediate process termination with a debugging message.
CVSS Score: N/A
D
No data available.
No data available.
1. Risk Assessment
The vulnerability, CVE-2017-3226, resides within Das U-Boot, a widely used device bootloader. It’s a parsing error triggered by a crafted two-byte sequence within the AES-CBC encrypted environment data. The vulnerability’s nature is primarily a denial-of-service (DoS) condition, causing an immediate process termination. However, the underlying cryptographic implementation may be affected, potentially allowing for decryption of the environment data with further exploitation. The business impact is moderate. While not a direct compromise of data, a DoS during boot can lead to downtime, impacting operations. The likelihood of exploitation is moderate, requiring physical access to the device, but the ease of exploitation is relatively high once physical access is gained as it involves manipulating the encrypted environment data. Confidentiality is potentially impacted if the underlying encryption is weakened, integrity is affected by the manipulated environment data, and availability is impacted by the process termination. The EPSS score of 0.000420000 indicates a relatively low, but present, probability of exploitation.
2. Potential Attack Scenarios
An attacker with physical access to a device utilizing U-Boot with environment encryption (CONFIG_ENV_AES=y) can craft a malicious encrypted environment image. The attacker would modify the encrypted environment data to include the triggering two-byte sequence. Upon boot, U-Boot reads the encrypted environment, attempts to parse the crafted sequence, and crashes, preventing the device from fully booting. This could impact embedded systems in production, industrial control systems, or network appliances. The attack vector is physical access, and the attack process involves replacing or modifying the encrypted environment image on the storage medium. The potential outcome is a device that fails to boot, leading to downtime and potentially impacting critical operations. Further analysis of the underlying AES-CBC implementation could allow the attacker to decrypt the environment variables and potentially gain further control.
3. Mitigation Recommendations
The primary mitigation is to upgrade U-Boot to a version newer than 2017.09. This upgrade addresses the improper error handling in the environment variable parsing. Organizations should prioritize patching systems that are critical to operations and those with easier physical access points. Regularly review and update the U-Boot version in embedded systems. Verify the integrity of the encrypted environment image after patching to ensure the vulnerability is fully resolved. Security hardening practices for physical access to devices should be implemented or reviewed to minimize the attack surface. Relevant resources include the SecurityFocus bid: http://www.securityfocus.com/bid/100675 and the CERT vulnerability note: https://www.kb.cert.org/vuls/id/166743.
4. Executive Summary
CVE-2017-3226 is a vulnerability in Das U-Boot that can cause a denial-of-service condition upon boot if the device uses AES encryption for its environment variables. An attacker with physical access can manipulate the encrypted environment data to crash the bootloader. While the initial impact is primarily downtime, there’s potential for further exploitation of the underlying encryption. To mitigate this risk, upgrade U-Boot to version 2017.09 or later. This is particularly important for devices critical to business operations. Prioritizing patching and securing physical access will minimize the risk of disruption and potential data compromise. Addressing this vulnerability will ensure the reliable operation of our embedded systems and reduce potential downtime.