US-CERT.gov

Feliratkozás US-CERT.gov hírcsatorna csatornájára
CERT publishes vulnerability advisories called "Vulnerability Notes." Vulnerability Notes include summaries, technical details, remediation information, and lists of affected vendors. Many vulnerability notes are the result of private coordination and disclosure efforts.
Frissítve: 22 perc 10 másodperc

VU#763073: iTerm2 with tmux integration is vulnerable to remote command execution

sze, 10/09/2019 - 16:43
iTerm2 is a popular terminal emulator for macOS that supports terminal multiplexing using tmux integration and is frequently used by developers and system administrators. A vulnerability,identified as CVE-2019-9535,exists in the way that iTerm2 integrates with tmux's control mode,which may allow an attacker to execute arbitrary commands by providing malicious output to the terminal. This affects versions of iTerm2 up to and including 3.3.5.
Kategóriák: Biztonsági hírek

VU#719689: Multiple vulnerabilities found in the Cobham EXPLORER 710 satcom terminal

sze, 10/09/2019 - 14:07
The Cobham EXPLORER 710 is a portable satellite terminal used to provide satellite telecommunications and internet access. For consistency,“device” mentioned in the following section is defined as the Cobham EXPLORER 710. The affected firmware version is 1.07 for all of the vulnerabilities listed below unless otherwise noted. CVE-2019-9529 The web application portal has no authentication by default. This could allow an unauthenticated,local attacker connected to the device to access the portal and to make any change to the device. CVE-2019-9530 The web root directory has no access restrictions on downloading and reading all files. This could allow an unauthenticated,local attacker connected to the device to access and download any file found in the web root directory. CVE-2019-9531 The web application portal allows unauthenticated access to port 5454 on the device. This could allow an unauthenticated,remote attacker to connect to this port via Telnet and execute 86 Attention(AT)commands,including some that provide unauthenticated,shell-like access to the device. CVE-2019-9532 The web application portal sends the login password in cleartext. This could allow an unauthenticated,local attacker to intercept the password and gain access to the portal. CVE-2019-9533 The root password for the device is the same for all versions of firmware up to and including v1.08. This could allow an attacker to reverse-engineer the password from available versions to gain authenticated access to the device. CVE-2019-9534 The device does not validate its firmware image. Development scripts left in the firmware can be used to upload a custom firmware image that the device runs. This could allow an unauthenticated,local attacker to upload their own firmware that could be used to intercept or modify traffic,spoof or intercept GPS traffic,exfiltrate private data,hide a backdoor,or cause a denial-of-service. In addition to the findings above,we have found some configuration issues within the device that can leave it vulnerable to attackers. The default WiFi password is publicly documented as the serial number of the device and can be easily brute forced. Additionally,important security headers are missing,which leaves the device vulnerable to cross-site scripting and clickjacking.
Kategóriák: Biztonsági hírek

VU#672565: Exim servers that accept TLS connections are vulnerable to local and remote code execution with root privileges

p, 09/06/2019 - 20:30
Exim is an open source mail server or message transfer agent(MTA)that is used on Unix-like operating systems. Versions up to and including 4.92.1 of Exim incorrectly handle certain decoding operations during the intial TLS handshake. A local or remote attacker could execute arbitrary code with root privileges. Exim servers that accept TLS connections are vulnerable. This vulnerability is independent of the TLS library,so Exim servers that use either GnuTLS and OpenSSL are affected.m
Kategóriák: Biztonsági hírek

VU#918987: Bluetooth BR/EDR supported devices are vulnerable to key negotiation attacks

sze, 08/14/2019 - 15:17
Bluetooth is a short-range wireless technology based off of a core specification that defines six different core configurations,including the Bluetooth Basic Rate/Enhanced Data Rate Core Configurations. Bluetooth BR/EDR is used for low-power short-range communications. To establish an encrypted connection,two Bluetooth devices must pair with each other and establish a link key that is used to generate the encryption key. For example,assume that there are two controllers attempting to establish a connection:Alice and Bob. After authenticating the link key,Alice proposes that she and Bob use 16 bytes of entropy. This number,N,could be between 1 and 16 bytes. Bob can either accept this,reject this and abort the negotiation,or propose a smaller value. Bob may wish to propose a smaller N value because he(the controller)does not support the larger amount of bytes proposed by Alice. After proposing a smaller amount,Alice can accept it and request to activate link-layer encryption with Bob,which Bob can accept. An attacker,Charlie,could force Alice and Bob to use a smaller N by intercepting Alice's proposal request to Bob and changing N. Charlie could lower N to as low as 1 byte,which Bob would subsequently accept since Bob supports 1 byte of entropy and it is within the range of the compliant values. Charlie could then intercept Bob's acceptance message to Alice and change the entropy proposal to 1 byte,which Alice would likely accept,because she may believe that Bob cannot support a larger N. Thus,both Alice and Bob would accept N and inform the Bluetooth hosts that encryption is active,without acknowledging or realizing that N is lower than either of them initially intended it to be.
Kategóriák: Biztonsági hírek

VU#605641: HTTP/2 implementations do not robustly handle abnormal traffic and resource exhaustion

k, 08/13/2019 - 19:53
The Security Considerations section of RFC7540 discusses some of the considerations needed for HTTP/2 connections as they demand more resources to operate than HTTP/1.1 connections. While it generally covers expected behavior considerations,how to mitigate abnormal behavior is left to the implementer which can leave it open to the following weaknesses. CVE-2019-9511,also known as Data Dribble The attacker requests a large amount of data from a specified resource over multiple streams. They manipulate window size and stream priority to force the server to queue the data in 1-byte chunks. Depending on how efficiently this data is queued,this can consume excess CPU,memory,or both,potentially leading to a denial of service. CVE-2019-9512,also known as Ping Flood The attacker sends continual pings to an HTTP/2 peer,causing the peer to build an internal queue of responses. Depending on how efficiently this data is queued,this can consume excess CPU,memory,or both,potentially leading to a denial of service. CVE-2019-9513,also known as Resource Loop The attacker creates multiple request streams and continually shuffles the priority of the streams in a way that causes substantial churn to the priority tree. This can consume excess CPU,potentially leading to a denial of service. CVE-2019-9514,also known as Reset Flood The attacker opens a number of streams and sends an invalid request over each stream that should solicit a stream of RST_STREAM frames from the peer. Depending on how the peer queues the RST_STREAM frames,this can consume excess memory,CPU,or both,potentially leading to a denial of service. CVE-2019-9515,also known as Settings Flood The attacker sends a stream of SETTINGS frames to the peer. Since the RFC requires that the peer reply with one acknowledgement per SETTINGS frame,an empty SETTINGS frame is almost equivalent in behavior to a ping. Depending on how efficiently this data is queued,this can consume excess CPU,memory,or both,potentially leading to a denial of service. CVE-2019-9516,also known as 0-Length Headers Leak The attacker sends a stream of headers with a 0-length header name and 0-length header value,optionally Huffman encoded into 1-byte or greater headers. Some implementations allocate memory for these headers and keep the allocation alive until the session dies. This can consume excess memory,potentially leading to a denial of service. CVE-2019-9517,also known as Internal Data Buffering The attacker opens the HTTP/2 window so the peer can send without constraint; however,they leave the TCP window closed so the peer cannot actually write(many of)the bytes on the wire. The attacker then sends a stream of requests for a large response object. Depending on how the servers queue the responses,this can consume excess memory,CPU,or both,potentially leading to a denial of service. CVE-2019-9518,also known as Empty Frame Flooding The attacker sends a stream of frames with an empty payload and without the end-of-stream flag. These frames can be DATA,HEADERS,CONTINUATION and/or PUSH_PROMISE. The peer spends time processing each frame disproportionate to attack bandwidth. This can consume excess CPU,potentially leading to a denial of service.
Kategóriák: Biztonsági hírek

VU#489481: Cylance Antivirus Products Susceptible to Concatenation Bypass

cs, 08/01/2019 - 18:00
Cylance PROTECT is an endpoint protection system. It contains an antivirus functionality that uses a machine learning algorithm(specifically,a neural network)to classify executables as malicious or benign. Security researchers isolated properties of the machine learning algorithm allowing them to change most known-malicious files in simple ways that cause the Cylance product to misclassify the file as benign. Several common malware families,such as Dridex,Gh0stRAT,and Zeus,were reported as successfully modified to bypass the Cylance product in this way. The success rate of the bypass is reported as approximately 85%of malicious files tested. Cylance reports a 50%bypass creation success rate based on internal testing. Either way,attacker effort to find a successful bypass would be low. Unsophisticated attackers can leverage this flaw to change any executable to which they have access; the defense evasion does not require rewriting the malware,just appending strings to it. The specific attack reported by Skylight Cyber relies on a particular set of strings used by the Cylance product. Although Cylance used an ensemble model that made some uncommon model design choices to achieve a white-listing functionality,this over-reliance on specific details when classifying a file is an instance of a common weakness in machine learning algorithms. For a comprehensive discussion of attacks on machine learning systems,see Papernot N,McDaniel P,Sinha A,Wellman MP. SoK:Security and privacy in machine learning. IEEE EuroS&P 2018. Because this flaw is an instance of a broader category of weaknesses in machine learning algorithms,we do not expect an easy solution. Cylance describes their response as"three-fold:First,we have added anti-tampering controls to the parser in order to detect feature manipulation and prevent them from impacting the model score. Second,we have strengthened the model itself to detect when certain features become proportionally overweight. Lastly,we have removed the features in the model that were most susceptible to tampering."This patch should stop the specific keywords used by the Skylight Cyber researchers from allowing an attacker to bypass detection and increase attacker effort required to find similar bypass techniques. However,the method described by the Skylight Cyber researchers to find and recover the features of the Cylance product is likely to enable the recovery of manipulable features from other security products that rely on machine learning. Although Cylance has removed features"most susceptible to tampering,"our understanding of adversarial manipulation of machine learning classifiers in other domains suggests that the remaining features almost certainly provide adequate freedom for tampering. This inference is based on the structural similarity of the Cylance machine learning model(a neural network)to models that have been successfully deceived in the domains of,for example,facial recognition or visual recognition in self-driving cars. There is some evidence that deception remains relatively easy despite the structure of computer network traffic; we are unaware of public evidence as to whether file structure carries the same limitations. This environment is the context behind and likely driver of Cylance's statement that"AI and machine learning models are,by nature,living models. They are designed to evolve and do require periodic retraining and field servicing when appropriate."
Kategóriák: Biztonsági hírek

VU#790507: Oracle Solaris vulnerable to arbitrary code execution via /proc/self

sze, 07/17/2019 - 12:14
The process file system(/proc)in Oracle Solaris 11 and Solaris 10 provides a self/alias that refers to the current executing process's PID subdirectory with state information about the process. Protection mechanisms for/proc in Solaris 11/10 did not properly restrict the current(self)process from modifying itself via/proc. For services strictly providing file IO this lack of restriction allows an attacker to modify the process providing the file IO and execute arbitrary code.
Kategóriák: Biztonsági hírek

VU#129209: LLVMs Arm stack protection feature can be rendered ineffective

h, 07/15/2019 - 16:01
The Stack Protection feature provided in the LLVM Arm backend protects against buffer overflows by adding a cookie value between local variables and the stack frame return address. The compiler stores this value in memory and checks the cookie with the LocalStackSlotAllocation function to ensure that it has not changed or been overwritten. If the value has changed,then the function will terminate. Since it currently pre-allocates the stack protector before the local variables in the stack,it's possible that a new stack protector can be allocated later in the process. If that happens,it leaves the stack protection ineffective as the new stack protector slot appears after the local variables that it is meant to protect.
Kategóriák: Biztonsági hírek

VU#905115: Multiple TCP Selective Acknowledgement (SACK) and Maximum Segment Size (MSS) networking vulnerabilities may cause denial-of-service conditions in Linux and FreeBSD kernels

h, 07/08/2019 - 16:21
CVE-2019-11477:SACK Panic(Linux>=2.6.29). A sequence of specifically crafted selective acknowledgements(SACK)may trigger an integer overflow,leading to a denial of service or possible kernel failure(panic). CVE-2019-11478:SACK Slowness(Linux<4.15)or Excess Resource Usage(all Linux versions). A sequence of specifically crafted selective acknowledgements(SACK)may cause a fragmented TCP queue,with a potential result in slowness or denial of service. CVE-2019-5599:SACK Slowness(FreeBSD 12 using the RACK TCP Stack). The TCP loss detection algorithm,Recent ACKnowledgment(RACK),uses time and packet or sequence counts to detect losses. RACK uses linked lists to track and identify missing packets. A sequence of specifically crafted acknowledgements may cause the linked lists to grow very large,thus consuming CPU or network resources,resulting in slowness or denial of service. CVE-2019-11479:Excess Resource Consumption Due to Low MSS Values(all Linux versions). The default maximum segment size(MSS)is hard-coded to 48 bytes which may cause an increase of fragmented packets. This vulnerability may create a resource consumption problem in both the CPU and network interface,resulting in slowness or denial of service. For detailed descriptions of these vulnerabilities,see: https://github.com/Netflix/security-bulletins/blob/master/advisories/third- party/2019-001.md
Kategóriák: Biztonsági hírek