CVE-2020-13848 in Portable UPnP SDK
Summary
by MITRE
Portable UPnP SDK (aka libupnp) 1.12.1 and earlier allows remote attackers to cause a denial of service (crash) via a crafted SSDP message due to a NULL pointer dereference in the functions FindServiceControlURLPath and FindServiceEventURLPath in genlib/service_table/service_table.c.
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Analysis
by VulDB Data Team • 06/05/2020
The vulnerability CVE-2020-13848 affects the Portable UPnP SDK library version 1.12.1 and earlier, representing a critical denial of service flaw that can be exploited remotely through specially crafted SSDP messages. This issue resides within the genlib/service_table/service_table.c source file and specifically targets two functions: FindServiceControlURLPath and FindServiceEventURLPath. The root cause of this vulnerability is a NULL pointer dereference condition that occurs when the library processes malformed SSDP traffic, leading to unexpected application crashes and system instability. This flaw demonstrates a classic software reliability issue where insufficient input validation allows malicious actors to trigger memory access violations that terminate legitimate service operations.
The technical implementation of this vulnerability stems from inadequate parameter validation within the UPnP service table processing logic. When the affected library receives an SSDP message containing malformed service control or event URLs, the FindServiceControlURLPath and FindServiceEventURLPath functions fail to properly check for NULL return values from internal lookup operations. This oversight creates a scenario where the application attempts to dereference a NULL pointer, causing an immediate crash. The vulnerability aligns with CWE-476 which specifically addresses NULL pointer dereference conditions in software implementations. The flaw exists because the library does not implement proper defensive programming practices to handle edge cases in service table lookups, particularly when processing malformed network traffic from untrusted sources.
From an operational perspective, this vulnerability poses significant risks to network infrastructure and device management systems that rely on UPnP functionality for device discovery and service control. The denial of service impact can disrupt network operations and potentially affect critical services that depend on UPnP for device communication and configuration. Attackers can exploit this vulnerability by sending carefully crafted SSDP packets to devices running vulnerable versions of the Portable UPnP SDK, causing the affected services to crash repeatedly. This can lead to network outages, device unavailability, and potential cascading failures in larger network deployments where UPnP services are integral to device management and communication protocols. The vulnerability affects any system that implements the libupnp library for UPnP service discovery and control, making it particularly concerning for home routers, network appliances, and IoT devices that commonly utilize UPnP functionality.
Organizations should immediately implement mitigation strategies to protect against this vulnerability by upgrading to version 1.12.2 or later of the Portable UPnP SDK where the NULL pointer dereference has been corrected. The fix typically involves adding proper NULL checks before pointer dereference operations in the affected functions, ensuring that service table lookups return appropriate error conditions rather than allowing NULL values to propagate through the code execution path. Network administrators should also consider implementing network-level filtering to restrict incoming SSDP traffic from untrusted sources and monitor for unusual patterns of SSDP message exchanges that might indicate exploitation attempts. Additionally, regular vulnerability assessments should be conducted to identify other potential instances of similar NULL pointer dereference conditions within the network infrastructure, as this class of vulnerability often indicates broader code quality issues that may manifest in other areas of the software stack. The ATT&CK framework categorizes this vulnerability under T1499.004 for Network Denial of Service and T1071.004 for Application Layer Protocol, highlighting its potential impact on network availability and service integrity.