CVE-2011-3581 in ldns
Summary
by MITRE
Heap-based buffer overflow in the ldns_rr_new_frm_str_internal function in ldns before 1.6.11 allows remote attackers to cause a denial of service (crash) and possibly execute arbitrary code via a Resource Record (RR) with an unknown type containing input that is longer than a specified length.
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Analysis
by VulDB Data Team • 11/26/2021
The vulnerability identified as CVE-2011-3581 represents a critical heap-based buffer overflow within the ldns library's ldns_rr_new_frm_str_internal function, affecting versions prior to 1.6.11. This flaw exists in the domain name system resolution library that is widely used for DNS client and server implementations across numerous operating systems and network applications. The issue arises when processing Resource Record (RR) data structures that contain unknown record types with input exceeding predetermined length limits, creating a dangerous condition where memory corruption can occur during parsing operations.
The technical implementation of this vulnerability stems from insufficient input validation and boundary checking within the internal parsing routine responsible for constructing DNS resource records from string representations. When the ldns_rr_new_frm_str_internal function encounters a Resource Record with an unrecognized type identifier, it attempts to allocate heap memory based on an estimated size derived from the input data without proper bounds verification. This inadequate validation allows attackers to craft malicious DNS records containing oversized data fields that exceed the allocated buffer boundaries, leading to memory overwrite conditions that can corrupt adjacent heap memory structures.
The operational impact of this vulnerability extends beyond simple denial of service scenarios to potentially enable remote code execution in certain environments. Attackers can leverage this flaw by constructing specially crafted DNS responses or authoritative data containing malformed Resource Records with excessive input lengths. The resulting heap corruption can cause application crashes, system instability, and in vulnerable configurations, arbitrary code execution through controlled memory overwrite techniques. This vulnerability particularly affects DNS servers, resolvers, and any network infrastructure relying on ldns for DNS protocol handling, making it a significant concern for network security operations and infrastructure reliability.
Mitigation strategies for CVE-2011-3581 primarily focus on immediate software updates to ldns version 1.6.11 or later, which includes proper input validation and boundary checking mechanisms. Network administrators should also implement DNS filtering rules to detect and block malformed DNS responses, while monitoring for suspicious DNS traffic patterns that might indicate exploitation attempts. The vulnerability aligns with CWE-121 Heap-based Buffer Overflow, which specifically addresses buffer overflows occurring in heap memory allocations where insufficient bounds checking allows memory corruption. From an adversarial perspective, this vulnerability maps to ATT&CK technique T1059.007 for Command and Scripting Interpreter and T1499.004 for Endpoint Denial of Service, as attackers can leverage it for both system disruption and potential code execution. Organizations should also consider implementing memory protection mechanisms such as stack canaries, address space layout randomization, and heap integrity checking to further reduce the exploitability of similar vulnerabilities in their DNS infrastructure components.