CVE-2016-7167 in SPARC Enterprise M3000
Summary
by MITRE
Multiple integer overflows in the (1) curl_escape, (2) curl_easy_escape, (3) curl_unescape, and (4) curl_easy_unescape functions in libcurl before 7.50.3 allow attackers to have unspecified impact via a string of length 0xffffffff, which triggers a heap-based buffer overflow.
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Analysis
by VulDB Data Team • 05/29/2023
The vulnerability identified as CVE-2016-7167 represents a critical security flaw in the libcurl library affecting versions prior to 7.50.3. This issue manifests through four specific functions within the library that handle URL encoding and decoding operations. The flaw stems from improper handling of integer overflow conditions when processing strings of maximum possible length, specifically those approaching 0xffffffff bytes. The affected functions include curl_escape, curl_easy_escape, curl_unescape, and curl_easy_unescape, which are fundamental components for web communication and data transfer operations in numerous applications and systems. These functions are widely utilized across various software platforms, making the vulnerability particularly dangerous as it could be exploited by attackers to compromise systems that rely on libcurl for network operations.
The technical implementation of this vulnerability occurs when the affected functions process input strings that approach the maximum value of a 32-bit unsigned integer. During the processing of these strings, integer overflow conditions cause the calculation of buffer sizes to wrap around to extremely small values, creating heap-based buffer overflow conditions. When the system attempts to allocate memory based on these corrupted calculated sizes, it results in insufficient buffer allocation that can be overwritten by attacker-controlled data. This overflow condition allows for arbitrary code execution or system instability, as the heap memory layout becomes corrupted and can be manipulated to execute malicious code. The vulnerability operates at the intersection of memory safety and integer arithmetic, where the failure to properly validate input size parameters leads to catastrophic memory corruption.
The operational impact of CVE-2016-7167 extends across numerous software applications and systems that depend on libcurl for internet communications. Given that libcurl is used by popular web browsers, web servers, email clients, and numerous other network-dependent applications, a successful exploitation could compromise thousands of systems simultaneously. The vulnerability's exploitation potential aligns with attack patterns described in the MITRE ATT&CK framework under the technique of code injection, specifically targeting memory corruption vulnerabilities. The unspecified impact mentioned in the CVE description indicates that the consequences could range from denial of service to full system compromise depending on the execution environment and system configuration. This vulnerability particularly affects systems where input validation is insufficient and where the applications do not properly sanitize input before passing it to the vulnerable libcurl functions.
Mitigation strategies for CVE-2016-7167 primarily involve upgrading to libcurl version 7.50.3 or later, which includes proper integer overflow checks and bounds validation. System administrators should conduct comprehensive inventory assessments to identify all systems utilizing vulnerable versions of libcurl and prioritize patching operations accordingly. Additionally, implementing input validation measures at application layers can provide defense-in-depth protection, ensuring that strings passed to libcurl functions are properly bounded before processing. The vulnerability also highlights the importance of following secure coding practices as outlined in CWE-190, which addresses integer overflow and underflow conditions. Organizations should consider implementing runtime protections such as address space layout randomization and stack canaries to reduce the effectiveness of potential exploitation attempts, while also monitoring network traffic for signs of exploitation attempts against vulnerable systems.