CVE-2018-4012 in BrightCloud SDK
Summary
by MITRE
An exploitable buffer overflow vulnerability exists in the HTTP header-parsing function of the Webroot BrightCloud SDK. The function bc_http_read_header incorrectly handles overlong headers, leading to arbitrary code execution. An unauthenticated attacker could impersonate a remote BrightCloud server to trigger this vulnerability.
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Analysis
by VulDB Data Team • 06/23/2023
The vulnerability identified as CVE-2018-4012 represents a critical buffer overflow flaw within the Webroot BrightCloud SDK's HTTP header parsing mechanism. This issue resides in the bc_http_read_header function which fails to properly validate header length parameters during HTTP response processing. The flaw manifests when the SDK encounters HTTP responses containing excessively long header fields, causing the application to write beyond allocated memory boundaries. This type of vulnerability falls under CWE-121, which specifically addresses stack-based buffer overflow conditions where insufficient boundary checking allows attackers to overwrite adjacent memory locations. The vulnerability's exploitation potential is heightened by the fact that it requires no authentication, making it particularly dangerous in environments where the BrightCloud SDK processes untrusted network traffic.
The technical exploitation of this vulnerability occurs through carefully crafted HTTP responses that contain oversized header fields, typically exceeding the buffer's allocated capacity. When the bc_http_read_header function processes these malformed headers, it performs unchecked string operations that result in memory corruption. This memory corruption can overwrite return addresses, function pointers, or other critical control data structures within the application's execution context. The attacker can leverage this to redirect program execution flow and ultimately achieve arbitrary code execution. The vulnerability's impact extends beyond simple code execution as it allows attackers to impersonate legitimate BrightCloud servers, effectively enabling man-in-the-middle attacks against systems utilizing the SDK. This capability aligns with ATT&CK technique T1071.004, which covers protocol tunneling through HTTP headers, and T1059.007, covering command and scripting interpreter abuse.
Systems affected by this vulnerability include any application that integrates the Webroot BrightCloud SDK and processes HTTP responses from potentially malicious sources. The operational impact is severe as the vulnerability can be exploited remotely without authentication, making it particularly dangerous for web applications, network monitoring tools, and security appliances that rely on the BrightCloud SDK for threat intelligence. Attackers can leverage this vulnerability to gain unauthorized access to systems, escalate privileges, or establish persistent backdoors within the affected environments. The vulnerability's exploitation requires minimal privileges and can be automated, making it attractive to both automated attack tools and sophisticated threat actors. Organizations utilizing the BrightCloud SDK should immediately assess their exposure and implement mitigations to prevent potential compromise of their security infrastructure.
The recommended mitigation strategy involves applying the vendor-provided security patches that address the buffer overflow in the bc_http_read_header function. Additionally, network administrators should implement proper input validation and length checking mechanisms for HTTP headers within their firewalls and proxy servers. Organizations should also consider implementing network segmentation and monitoring to detect anomalous HTTP header patterns that might indicate exploitation attempts. The vulnerability demonstrates the importance of proper bounds checking in network protocol implementations and highlights the need for security-conscious development practices that prevent buffer overflow conditions. Security teams should also monitor for indicators of compromise related to this vulnerability and maintain updated threat intelligence feeds that may contain signatures for exploitation attempts.