Vulnerabilities > CVE-2017-0569 - Incorrect Calculation of Buffer Size vulnerability in Linux Kernel 3.10/3.18
Attack vector
NETWORK Attack complexity
HIGH Privileges required
NONE Confidentiality impact
COMPLETE Integrity impact
COMPLETE Availability impact
COMPLETE Summary
An elevation of privilege vulnerability in the Broadcom Wi-Fi driver could enable a local malicious application to execute arbitrary code within the context of the kernel. This issue is rated as High because it first requires compromising a privileged process. Product: Android. Versions: Kernel-3.10, Kernel-3.18. Android ID: A-34198729. References: B-RB#110666.
Vulnerable Configurations
| Part | Description | Count |
|---|---|---|
| OS | 2 |
Common Weakness Enumeration (CWE)
Common Attack Pattern Enumeration and Classification (CAPEC)
- Overflow Buffers Buffer Overflow attacks target improper or missing bounds checking on buffer operations, typically triggered by input injected by an attacker. As a consequence, an attacker is able to write past the boundaries of allocated buffer regions in memory, causing a program crash or potentially redirection of execution as per the attackers' choice.
- Buffer Overflow via Parameter Expansion In this attack, the target software is given input that the attacker knows will be modified and expanded in size during processing. This attack relies on the target software failing to anticipate that the expanded data may exceed some internal limit, thereby creating a buffer overflow.
Exploit-Db
| description | Broadcom Wi-Fi SoC - 'dhd_handle_swc_evt' Heap Overflow. CVE-2017-0569. Remote exploit for Hardware platform |
| file | exploits/hardware/remote/41808.txt |
| id | EDB-ID:41808 |
| last seen | 2017-04-04 |
| modified | 2017-04-04 |
| platform | hardware |
| port | |
| published | 2017-04-04 |
| reporter | Exploit-DB |
| source | https://www.exploit-db.com/download/41808/ |
| title | Broadcom Wi-Fi SoC - 'dhd_handle_swc_evt' Heap Overflow |
| type | remote |
Seebug
| bulletinFamily | exploit |
| description | roadcom produces Wi-Fi HardMAC SoCs which are used to handle the PHY and MAC layer processing. These chips are present in both mobile devices and Wi-Fi routers, and are capable of handling many Wi-Fi related events without delegating to the host OS. On Android devices, the "bcmdhd" driver is used in order to communicate with the Wi-Fi SoC (also referred to as "dongle"). When the dongle wishes to notify the host OS of an event, it does so by encoding a special "packet" and transmitting it to the host. These packets have an ether type of 0x886C (referred to as ETHER_TYPE_BRCM), and do not contain actual packet data, but rather encapsulate information about events which must be handled by the driver. After reading packets from the SDIO interface, the "bcmdhd" driver calls the function "dhd_rx_frame" to handle each of the received frames. If a frame has the special Broadcom ether type, it is passed on to an internal handling function, "dhd_wl_host_event". This function inspects the event code, and passes it onto the registered handlers for the given event type. The function "wl_notify_gscan_event" is the registered handler for events of the following types: ``` -WLC_E_PFN_BEST_BATCHING -WLC_E_PFN_SCAN_COMPLETE -WLC_E_PFN_GSCAN_FULL_RESULT -WLC_E_PFN_SWC -WLC_E_PFN_BSSID_NET_FOUND -WLC_E_PFN_BSSID_NET_LOST -WLC_E_PFN_SSID_EXT -WLC_E_GAS_FRAGMENT_RX ``` (for reference, see "wl_init_event_handler") Specifically, when the event code "WLC_E_PFN_SWC" is received, the gscan handler function calls "dhd_handle_swc_evt" in order to process the event's data, like so: ``` 1. void * dhd_handle_swc_evt(dhd_pub_t *dhd, const void *event_data, int *send_evt_bytes) 2. { 3. ... 4. wl_pfn_swc_results_t *results = (wl_pfn_swc_results_t *)event_data; 5. ... 6. gscan_params = &(_pno_state->pno_params_arr[INDEX_OF_GSCAN_PARAMS].params_gscan); 7. ... 8. if (!params->results_rxed_so_far) { 9. if (!params->change_array) { 10. params->change_array = (wl_pfn_significant_net_t *) 11. kmalloc(sizeof(wl_pfn_significant_net_t) * results->total_count, GFP_KERNEL); 12. ... 13. } 14. } 15. ... 16. change_array = ¶ms->change_array[params->results_rxed_so_far]; 17. memcpy(change_array, results->list, sizeof(wl_pfn_significant_net_t) * results->pkt_count); 18. params->results_rxed_so_far += results->pkt_count; 19. ... 20. } ``` (where "event_data" is the arbitrary data encapsulated in the event passed in from the dongle) When the function above is first invoked, the value of "`params->change_array`" is NULL. An attacker controlling the dongle may send a crafted `WLC_E_PFN_SWC` event, with the following values: ``` - results->total_count = SMALL_VALUE - result->pkt_count = LARGE_VALUE ``` Since the function fails to verify that "pkt_count" is not larger than "total_count", this would cause the allocated buffer (lines 10-11) to be smaller than the size used in the memcpy operation (line 17), thus overflowing the buffer. I've been able to statically verify these issues on the "bcmdhd-3.10" driver, and in the corresponding "bcmdhd" driver on the Nexus 6P's kernel (angler). |
| id | SSV:92900 |
| last seen | 2017-11-19 |
| modified | 2017-04-05 |
| published | 2017-04-05 |
| reporter | Root |
| title | Broadcom: Heap overflow in "dhd_handle_swc_evt"(CVE-2017-0569) |