Is grokking-algorithms-2nd-edition-2nd_compress.pdf safe?
No antivirus engine detected the PDF, but an isolated sandbox run produced uncorroborated LSASS and direct-IP indicators that warrant cautious handling.
All 74 antivirus engines were silent, including 17 reporting tier-1 engines, and the sandbox did not issue a malicious verdict. However, the run generated an LSASS-related heuristic and direct-IP contacts whose reputation was not checked, so the file should be opened only in an updated, protected PDF reader.
4bb4cb22fc5192a901…7d468815096e23Recommended next actions
Before opening
Do not open it until the source can be verified independently.
If you already opened it
Stop using it, scan the device, and watch for unexpected behavior or security alerts. Get a fresh copy from the original trusted source and verify its exact hash when possible.
Intelligence
The saved assessment, checked against the scan evidence and recorded coverage.
The reasoning behind this verdict
This section explains the evidence supporting the verdict and keeps conflicting or missing signals visible.
All 74 antivirus engines were silent, including 17 reporting tier-1 engines, and the sandbox did not issue a malicious verdict. However, the run generated an LSASS-related heuristic and direct-IP contacts whose reputation was not checked, so the file should be opened only in an updated, protected PDF reader.
The strongest evidence is that 0 of 74 antivirus engines flagged the PDF, including no detections from the reporting tier-1 engines. One completed sandbox run did not produce a malicious verdict, and none of the 10 inspected child artifacts was identified as malicious. However, the same run generated an LSASS-related heuristic associated with T1485 and recorded direct-IP traffic, which is unusual enough to prevent an unqualified benign assessment. Those indicators lack engine, sandbox-verdict, family, or external-intelligence corroboration and may reflect sandbox or PDF-reader background activity. Because host-reputation checking was not completed and every child verdict remains unknown, some uncertainty remains.
What We Detected
None of 74 antivirus engines flagged this PDF, and all 17 reporting tier-1 engines returned no detection. The file has also been submitted 119 times by 98 sources, providing more exposure than a newly observed sample.
Threat Behavior
One sandbox run did not issue a malicious verdict, and no inspected child was identified as malicious. However, the run generated MITRE T1485 and an LSASS-related credential-dumping heuristic, along with direct-IP contacts to 23.220.188.152, 23.63.158.36, and 23.22.254.206. These signals are not corroborated by engine detections or a named family, and no complete reputation result is available for the contacted hosts. All 10 child artifacts also remain unclassified.
What To Do Now
Use an updated PDF reader with endpoint protection enabled, and avoid enabling embedded content or following unexpected links. If the document came from an untrusted or unofficial source, obtain another copy from a reputable source before opening it on a sensitive system.
Where this verdict could be wrong3 caveats
- The sandbox-associated T1485 and LSASS-targeting heuristic are atypical for a PDF, though no malicious sandbox verdict or engine detection corroborates them.
- Direct-IP contacts were recorded, but contactedHosts=null means their reputation was not completely checked.
- All 10 inspected child artifacts have unknown verdicts, so hasMaliciousChild=false does not establish that they are benign.
These are the assessment's weak points. If you believe one applies to your file, report the verdict and we'll re-review it.
- 0/74 antivirus engines detected a threat
- tier1Malicious=0 with 17 reporting tier-1 engines clean
- behaviour.hasMaliciousSandboxVerdict=false
- droppedChildren.hasMaliciousChild=false
- 119 submissions from 98 sources
- Sandbox-associated MITRE T1485 indicator
- LSASS-related CredentialDumper heuristic
- Direct-IP contacts without a completed host-reputation check
- Ten dropped child artifacts remain unclassified
Prefer a copy from a reputable source and open it only with a fully updated PDF reader while endpoint protection remains enabled. Avoid embedded links or active content unless independently expected.
Coverage & freshness
Complete means the check returned a usable result. It does not mean the file is safe.
Antivirus
Complete0 of 74 engines flagged the file.
Sandbox
Complete1 isolated runtime environment contributed observations.
Network
Partial5 runtime contacts were observed without a completed reputation cross-check.
YARA
Complete2 signature or behavior rules matched.
External intel
Complete3 of 3 independent reference sources completed.
Behavior
Plain-English impact first, then the observed runtime evidence.
Runtime flight recorder
Capture complete- 1isolated sandbox run
- 9MITRE ATT&CK techniques
- 15spawned processes
- 5network contacts
- 32filesystem & mutex artifacts
What this file does
Observed actions and their security significance
Moderate concern: Communicated over a common application protocol; malware can use this for command-and-control.
Note: Collects details about your system.
These are observed capabilities from an isolated analysis. A technique does not prove malicious intent on its own, and the file never ran on your device.
Attack story
Runtime observations grouped by analysis stage. Arrows organize the stages; they do not claim chronology or causality.
Input file
The submitted object
- FileObserved
grokking-algorithms-2nd-edition-2nd_compress.pdf
4bb4cb22fc5192a901a934cf09841c6bc8e23d83db570b992e7d468815096e23
01Uploaded file
Processes
Runtime execution
- ProcessObserved
Observed process
"C:\Program Files\Adobe\Acrobat DC\Acrobat\Acrobat.exe" "C:\Users\<USER>\Desktop\s _2nd Edition_ _2024_ Manning Publications_ - libgen.li.pdf"
02Isolated runtime analysis - ProcessObserved
Observed process
"C:\Program Files\Adobe\Acrobat DC\Acrobat\Adobe Crash Processor.exe"
03Isolated runtime analysis - +1 more recorded observation in Analyst mode
Files
Created or changed
- Written fileObserved
acroNGLLog.txt
C:\Users\<USER>\AppData\Local\Temp\acroNGLLog.txt
04Isolated runtime analysis - Written fileObserved
NGL
C:\Users\<USER>\AppData\Local\Temp\NGL\
05Isolated runtime analysis - +1 more recorded observation in Analyst mode
Network
Hosts contacted
- Contacted hostObserved
23.220.188.152
Contact observed during runtime.
06Isolated runtime analysis - Contacted hostObserved
23.63.158.36
Contact observed during runtime.
07Isolated runtime analysis - +1 more recorded observation in Analyst mode
7 recorded facts from one runtime window. Every fact remains independently traceable in Analyst mode.
What this file did when executed
This file was detonated in 1 sandbox and its runtime behaviour was observed.
Adversary techniques mapped to the MITRE ATT&CK framework.
- 23.220.188.152
- 23.63.158.36
- 23.22.254.206
- 8.8.8.8
- 162.159.36.2
- C:\Users\<USER>\AppData\Local\Temp\acroNGLLog.txt
- C:\Users\<USER>\AppData\Local\Temp\NGL\
- C:\Users\<USER>\AppData\Local\Temp\Tmp6721.tmp
- C:\Users\<USER>\AppData\Local\Temp\Tmp6F5F.tmp
- C:\Windows\ServiceProfiles\LocalService\AppData\Local\FontCache\Fonts\Download-1.tmp
- C:\Users\<USER>\AppData\Roaming\Adobe\Acrobat\DC\JSCache\GlobSettings
- C:\Users\<USER>\AppData\Local\Packages\Microsoft.XboxGamingOverlay_8wekyb3d8bbwe\LocalCache\KnownGameList.bin
- C:\Users\<USER>\AppData\Local\Microsoft\GameDVR\KnownGameList.update
- C:\Users\<USER>\AppData\Local\Adobe\Acrobat\DC\SOPHIA\Reader\Files\DC_READER_LAUNCH_CARD
- C:\Users\<USER>\AppData\Local\Adobe\Acrobat\DC\SOPHIA\Reader\Files\ACROBAT_READER_MASTER_SURFACEID
- Global\MSILOG_fecd0d921dc63f4GOL.27171ISM_pmeT_lacoL_ataDppA_onurB_sresU_:C
- Global\AdobeCrashProcessorLocalLowLock
- \Sessions\1\BaseNamedObjects\{100184D2-BDC3-477a-B8D3-65548B67914C}_7960
- \Sessions\1\BaseNamedObjects\Local\{100184D2-BDC3-477a-B8D3-65548B67914C}_8088
- \Sessions\1\BaseNamedObjects\Local\Acrobat Instance Mutex
Files this sample writes at runtime
This file drops 10 children at runtime. None are currently flagged malicious in our cache.
- eacad3e01b8b0a44ac03…df796dNever scannednever seen before
- 513fb5d3b4195ab59af2…64de2eNever scannednever seen before
- ad27039abac3252c3b39…37ede5Never scannednever seen before
- 98238a8362768d6c825f…1ffc19Never scannednever seen before
- 81ff65efc4487853bdb4…7c8e06Never scannednever seen before
- 3b3c4b833e67df98b9fd…3af93fNever scannednever seen before
- e97fbf22c77421906dbb…3406f4Never scannednever seen before
- 00281827e080a237ab9e…e0888eNever scannednever seen before
- e3b0c44298fc1c149afb…52b855Never scannednever seen before
- a1a0894b57af5307b417…7b80d6Never scannednever seen before
Detection & Forensics
Consensus, attribution, signatures, code structure, prevalence, and identity.
Evidence integrity
Chain of custody for the facts preserved in this report.
- 2rule hits recorded
- 0 / 74engines flagged
- 98sources in submission history
Why these facts are shown
Each statement identifies whether it was directly recorded or derived from saved scan facts.
- 01
0 of 74 antivirus engines flagged the file.
ProvenanceObservedSourceAntivirus analysisObserved at - 02
The hash has been submitted 119 times from 98 sources.
ProvenanceDerivedSourceSaved report factsObserved at - 03
Scanned file: grokking-algorithms-2nd-edition-2nd_compress.pdf — 4bb4cb22fc5192a901a934cf09841c6bc8e23d83db570b992e7d468815096e23
ProvenanceObservedSourceUploaded fileObserved at - 04
Observed process — "C:\Program Files\Adobe\Acrobat DC\Acrobat\Acrobat.exe" "C:\Users\<USER>\Desktop\s _2nd Edition_ _2024_ Manning Publications_ - libgen.li.pdf"
ProvenanceObservedSourceIsolated runtime analysisObserved at - 05
Observed process — "C:\Program Files\Adobe\Acrobat DC\Acrobat\Adobe Crash Processor.exe"
ProvenanceObservedSourceIsolated runtime analysisObserved at - 06
File written: acroNGLLog.txt — C:\Users\<USER>\AppData\Local\Temp\acroNGLLog.txt
ProvenanceObservedSourceIsolated runtime analysisObserved at - 07
File written: NGL — C:\Users\<USER>\AppData\Local\Temp\NGL\
ProvenanceObservedSourceIsolated runtime analysisObserved at - 08
Contacted host: 23.220.188.152 — Contact observed during runtime.
ProvenanceObservedSourceIsolated runtime analysisObserved at - 09
Contacted host: 23.63.158.36 — Contact observed during runtime.
ProvenanceObservedSourceIsolated runtime analysisObserved at
Detection sources at a glance
The available sources did not agree on a named threat category.
MalwareBazaar, YARAify, and CIRCL hashlookup completed and returned no entries for this hash.
Signatures and behavior heuristics
Behavioral heuristics matched patterns associated with malware. Corroborating evidence determines how much weight they carry.
Sandbox observed process activity targeting LSASS (Windows credential store). Legitimate software has no business reading LSASS memory — this is Mimikatz-shape behaviour.
EvidenceC:\Windows\system32\lsass.exeThe sample contacted an external IP address directly and no application domain was recorded. Direct-IP traffic also occurs in legitimate installers and infrastructure, so this is supporting context only and requires corroboration from host reputation and other runtime evidence.
Evidence23.220.188.152 · 23.63.158.36 · 23.22.254.206
0 of 74 engines flagged this file
View all 74 engine results
PE structure
Not applicablePE structure analysis applies to Windows executable formats, not this file type.
How widely this file has been seen
Moderate prevalence — neither rare nor common. No strong prior applies.
Fingerprint and provenance
- File name
- grokking-algorithms-2nd-edition-2nd_compress.pdf
- Format
- Code signing
- Not applicable to this file type
- Size
- 2.9 MB
- Last analyzed
- Sep 19, 2026, 8:28 AM UTC
4bb4cb22fc5192a901a934cf09841c6bc8e23d83db570b992e7d468815096e23Safety & FAQ
Complete recovery guidance and answers for the next decision.
What to do now
We couldn't fully clear this file. Treat it with caution.
- Recovery step 01
Don't open it unless you're certain it came from a source you trust.
- Recovery step 02
Check where you got it — an unexpected attachment or a random download link is a red flag.
- Recovery step 03
If its origin cannot be confirmed, delete this file and use a fresh copy from a trusted source. Get a fresh copy from the original trusted source and verify its exact hash when possible.
- Recovery step 04
If you're still unsure, scan it again in a day or two — detections often catch up on newer files.
Safety FAQ
Direct answers grounded in the saved verdict and evidence in this report.
Is grokking-algorithms-2nd-edition-2nd_compress.pdf safe, or is it malware?
What is grokking-algorithms-2nd-edition-2nd_compress.pdf?
How many antivirus engines detected grokking-algorithms-2nd-edition-2nd_compress.pdf?
What should I do if I already opened grokking-algorithms-2nd-edition-2nd_compress.pdf?
How do I remove grokking-algorithms-2nd-edition-2nd_compress.pdf?
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How up to date is this analysis of grokking-algorithms-2nd-edition-2nd_compress.pdf?
Community
Member reviews and reports for this exact file hash.