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.
Below is a copy: Boa Web Server 0.94.13 / 0.94.14 Authentication Bypass
# Exploit Title: Boa Web Server 0.94.13-0.94.14 Authentication Bypass
# Date: 19-11-2022
# Exploit Author: George Tsimpidas
# Vendor: https://github.com/gpg/boa
# CVE: N/A
# Tested on: Debian 5.18.5
Description :
Boa Web Server Versions from 0.94.13 - 0.94.14 fail to validate the
correct security constraint on the HEAD http method allowing everyone
to bypass the Basic Authorization Mechanism.
Culprit :
if (!memcmp(req->logline, "GET ", 4))
req->method = M_GET;
else if (!memcmp(req->logline, "HEAD ", 5))
/* head is just get w/no body */
req->method = M_HEAD;
else if (!memcmp(req->logline, "POST ", 5))
req->method = M_POST;
else {
log_error_doc(req);
fprintf(stderr, "malformed request: \"%s\"\n", req->logline);
send_r_not_implemented(req);
return 0;
}
The req->method = M_HEAD; is being parsed directly on the response.c
file, looking at how the method is being implemented for one of the
response codes :
/* R_NOT_IMP: 505 */
void send_r_bad_version(request * req)
{
SQUASH_KA(req);
req->response_status = R_BAD_VERSION;
if (!req->simple) {
req_write(req, "HTTP/1.0 505 HTTP Version Not Supported\r\n");
print_http_headers(req);
req_write(req, "Content-Type: " HTML "\r\n\r\n"); /* terminate
header */
}
if (req->method != M_HEAD) {
req_write(req,
"<HTML><HEAD><TITLE>505 HTTP Version Not
Supported</TITLE></HEAD>\n"
"<BODY><H1>505 HTTP Version Not Supported</H1>\nHTTP
versions "
"other than 0.9 and 1.0 "
"are not supported in Boa.\n<p><p>Version encountered: ");
req_write(req, req->http_version);
req_write(req, "<p><p></BODY></HTML>\n");
}
req_flush(req);
}
Above code condition indicates that if (req->method != M_HEAD) therefore
if the the requested method does not equal to M_HEAD then
req_write(req,
"<HTML><HEAD><TITLE>505 HTTP Version Not
Supported</TITLE></HEAD>\n"
"<BODY><H1>505 HTTP Version Not Supported</H1>\nHTTP
versions "
"other than 0.9 and 1.0 "
"are not supported in Boa.\n<p><p>Version encountered: ");
req_write(req, req->http_version);
req_write(req, "<p><p></BODY></HTML>\n");
}
So if the method actually contains the http method of HEAD it's being
passed for every function that includes all the response code methods.
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